Goggy Davidowitz

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• Davidowitz, G., Hood-Nowotny, R., Simmons, G. S., McDonough, E. R., & Greene, T. D. (2017). Development of stable isotopes and new biochemical tools for identification of sterile insects and determination of pest origin. In USDA, APHIS, OTIS CPHST Laboratory Report.
• Davidowitz, G. -. (2015). Grasshoppers. In A Natural History of the Sonoran Desert (second edition)(pp 287-289). Arizona Sonora Desert Museum.
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  Davidowitz, G. (2015). Grasshoppers. In: Mark A. Dimmitt, Patricia Wentworth Comus, and Linda M. Brewer (eds.) A Natural History of the Sonoran Desert (second edition) pp. 287-289. Arizona-Sonora Desert Museum.
• Davidowitz, G. -., & Helm, B. R. (2015). Commonalities in the regulation of growth and size: Can we see the forest for the trees?. In Integrative Organismal Biology(pp 207-217). Wiley and Sons.
• Davidowitz, G., & Helm, B. R. (2015). A Common Framework for the Regulation of Growth and Size: Stepping Away from the Trees to See the Forest. In Integrative Organismal Biology(pp 207-217). John Wiley & Sons, Inc. doi:10.1002/9781118398814.CH13
• Nijhout, H. F., Davidowitz, G., Whitman, D. W., & Ananthakrishnan, T. N. (2009). The developmental-physiological basis of phenotypic plasticity.. In Phenotypic Plasticity in Insects: Mechanisms and Consequences(pp 589-608). Science Publishers, Inc.
• Bronstein, J. L., Huxman, T. E., Huxman, T. E., & Davidowitz, G. (2007). Ecological Communities: Plant-mediated effects linking herbivory and pollination. In Ecological Communities: Plant Mediation in Indirect Interaction Webs(pp 75-103). Cambridge University Press. doi:10.1017/CBO9780511542701.005

Journals/Publications

• Davidowitz, G. (2021). Habitat-centric versus species-centric approaches to edible insects for food and feed. Current Opinion in Insect Science, 48, 37-43.
• Gutierrez-Jaramillo, A., Davidowitz, G., Waller, P. M., & Pryor, B. M. (2021). Bioregenerative Food Production System: Using integrated food production systems to feed the future. International Conference on Environmental Systems ICES, 2021-169.
• Preyer, C., & Davidowitz, G. (2021). The time is ripe for expanded research on mass production of insects as food and feed. Current Opinion in Insect Science, 48, viii-xi.
• Smith, G. P., Papaj, D. R., Davidowitz, G., Bronstein, J. L., & Alarcon, R. (2021). Sex differences in the foraging behavior of a generalist hawkmoth.. Insect science. doi:10.1111/1744-7917.12926
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  Within-species variation in pollinator behavior is widely observed, but its causes have been minimally investigated. Pollinator sex is associated with large differences in behavior that may lead to predictable differences in flower foraging, but this expectation has not been explicitly tested. We investigate sex-associated differences in nectar-foraging behavior of the hawkmoth Hyles lineata, using pollen on the proboscis as a proxy for flower visitation. We tested two predictions emerging from the literature: (1) the sexes differ in the flower species they visit, (2) females are more specialized in flower choice. We also examined potential drivers underlying these predictions by performing field and laboratory experiments to test whether males (3) switch among flower species more frequently, or (4) fly farther and therefore encounter more species than females. Consistent with prediction (1), pollen load composition differed between the sexes, indicative of visitation differences. Contrary to prediction (2), females consistently carried more species-rich pollen loads than males. (3) Both sexes switched between flower species at similar rates, suggesting that differences in floral fidelity are unlikely to explain why females are less specialized than males. (4) Males flew longer distances than females; coupled with larger between-site differences in pollen composition for females, this result suggests that sex differences in mobility influence foraging, and that females may forage more frequently and in smaller areas than males. Together, our results demonstrate that sex-associated foraging differences can be large and consistent over time, and highlight the importance of sex as a driver of variation in pollinator behavior.
• Smith, G., Davidowitz, G., Raguso, R., & Bronstein, J. (2021). Proboscis curling in a pollinator causes extensive pollen movement and loss. Ecological Entomology. doi:10.1111/een.13105
• Yule, K. M., Smith, G. P., Johnson, C. A., Ferriere, R., Davidowitz, G., & Bronstein, J. L. (2021). Coevolutionary transitions from antagonism to mutualism explained by the Co-Opted Antagonist Hypothesis.. Nature communications, 12(1), 2867. doi:10.1038/s41467-021-23177-x
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  There is now good evidence that many mutualisms evolved from antagonism; why or how, however, remains unclear. We advance the Co-Opted Antagonist (COA) Hypothesis as a general mechanism explaining evolutionary transitions from antagonism to mutualism. COA involves an eco-coevolutionary process whereby natural selection favors co-option of an antagonist to perform a beneficial function and the interacting species coevolve a suite of phenotypic traits that drive the interaction from antagonism to mutualism. To evaluate the COA hypothesis, we present a generalized eco-coevolutionary framework of evolutionary transitions from antagonism to mutualism and develop a data-based, fully ecologically-parameterized model of a small community in which a lepidopteran insect pollinates some of its larval host plant species. More generally, our theory helps to reconcile several major challenges concerning the mechanisms of mutualism evolution, such as how mutualisms evolve without extremely tight host fidelity (vertical transmission) and how ecological context influences evolutionary outcomes, and vice-versa.
• Davidowitz, G. (2020). Size variation does not act as insurance in bumblebees, instead workers added weight in an unpredictable environment. Animal Behaviour, 170, 99-109.
• Francois, C., & Davidowitz, G. (2020). Genetic color polymorphism of the white lined sphinx moth larva, Hyles lineata (Lepidoptera: Sphingidae). Journal of Insect Science, 1-9(4), 20.
• Jeffrey Gutierrez, E., Walker, K. R., Ernst, K. C., Riehle, M. A., & Davidowitz, G. (2020). Size as a Proxy for Longevity in Aedes aegypti (Diptera: Culicidae) Mosquitoe. Journal of Medical Entomology, 57, 1228-1238.
• Jeffrey Gutiérrez, E., Walker, K. R., Ernst, K. C., Riehle, M. A., & Davidowitz, G. (2020). Size as a Proxy for Longevity in Aedes aegypti (Diptera: Culicidae) Mosquitoes. Journal of Medical Entomology.
• McAll, A. C., Davidowitz, G., & Bronstein, J. (2020). How high are the costs inflicted by an herbivorous pollinator?. Arthropod-Plant Interactions, 14, 387-397.
• Wilson, K., Ruiz, L., & Davidowitz, G. (2020). Within-host competition drives energy allocation trade-offs in an insect parasitoid. Peer-J, 8, e8810. doi:DOI 10.7717/peerj.8810
• Davidowitz, G., Moore, A. F., von Arx, M., & Arnold, A. E. (2019). Diversity and composition of cultivable microbial communities in nectar of moth-pollinated plants in the Sonoran Desert. PLoS ONE, 14, e0225309.
• Kelemen, E. P., Cao, N., Cao, T., Davidowitz, G., & Dornhaus, A. (2019). Metabolic rate predicts the lifespan of workers in the bumble bee Bombus impatiens. APIDOLOGIE, 50(2), 195-203.
• Tigreros, N., & Davidowitz, G. (2019). Flight-fecundity tradeoffs in wing-monomorphic insects. ADVANCES IN INSECT PHYSIOLOGY, VOL 56, 56, 1-+.
• Wilson, J. K., Ruiz, L., & Davidowitz, G. (2019). Dietary protein and carbohydrates affect immune function and performance in a specialist herbivore insect Manduca sexta. Physiological and Biochemical Zoology, 92, 58-70.
• Wilson, J. K., Ruiz, L., Duarte, J., & Davidowitz, G. (2019). The nutritional landscape of host plants for a specialist insect herbivore. Ecology and Evolution, 9(23), 13104-13113.
• Ziv, Y., & Davidowitz, G. (2019). When Landscape Ecology Meets Physiology: Effects of Habitat Fragmentation on Resource Allocation Trade-Offs. FRONTIERS IN ECOLOGY AND EVOLUTION, 7.
• von Arx, M., Moore, A., Davidowitz, G., & Arnold, A. E. (2019). Diversity and distribution of microbial communities in floral nectar of two night-blooming plants of the Sonoran Desert. PloS one, 14(12), e0225309.
• Blanckenhorn, W. U., Bauerfeind, S. S., Berger, D., Davidowitz, G., Fox, C. W., Guillaume, F., Nakamura, S., Nishimura, K., Sasaki, H., Stillwell, C. R., Tachi, T., & Schafer, M. A. (2018). Life history traits, but not body size, vary systematically along latitudinal gradients on three continents in the widespread yellow dung fly. Ecography, 41, 2080-2091.
• Hildebrand, J. G., Wilson, J. K., Tseng, A. S., Potter, K. A., Hildebrand, J. G., & Davidowitz, G. (2018). THE EFFECTS OF THE ALKALOID SCOPOLAMINE ON THE PERFORMANCE AND BEHAVIOR OF TWO CATERPILLAR SPECIES.. Arthropod-plant interactions, 12(1), 21-29. doi:10.1007/s11829-017-9548-y
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  Plants have evolved many defenses against insect herbivores, including numerous chemicals that can reduce herbivore growth, performance, and fitness. One group of chemicals, the tropane alkaloids, is commonly found in the nightshade family (Solanaceae) and has been thought to reduce performance and fitness in insects. We examined the effects of the tropane alkaloid scopolamine, the alkaloid constituent of Datura wrightii, which is the most frequent host plant for the abundant and widespread insect herbivore Manduca sexta in the southwestern United States. We exposed caterpillars of two different species to scopolamine: M. sexta, which has a shared evolutionary history with Datura and other solanceous plants, and Galleria mellonella, which does not. We showed that the addition of ecologically-realistic levels of scopolamine to both the diet and the hemolymph of these two caterpillar species (M. sexta and G. mellonella) had no effect on the growth of either species. We also showed that M. sexta has no behavioral preference for or against scopolamine incorporated into an artificial diet. These results are contrary to other work showing marked differences in performance for other insect species when exposed to scopolamine, and provide evidence that scopolamine might not provide the broad-spectrum herbivore resistance typically attributed to it. It also helps to clarify the coevolutionary relationship between M. sexta and one of its main host plants, as well as the physiological mechanism of resistance against scopolamine.
• Johnson, C. A., Smith, G. P., Johnson, C. A., Davidowitz, G., & Bronstein, J. L. (2018). Linkages between nectaring and oviposition preferences of Manduca sexta on two co-blooming Datura species in the Sonoran Desert. Ecological Entomology, 43(1), 85-92. doi:10.1111/een.12475
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  Keep Engaging Youth in Science (KEYS) program of the University of Arizona BIO5 Institute; National Institute of Environmental and Health Sciences (NIEHS) [ES006694]; Science Foundation Arizona [BSP 0528-13]; National Science Foundation (NSF) [IOS-1053318]
• Nielsen, M. E., Eran, L., Davidowitz, G., & Papaj, D. R. (2018). Color alters thermoregulatory behavior in Battus philenor caterpillars by modifying the cue received. Animal Behavior, 140, 93-98.
• Schaller, J., Davidowitz, G., Papaj, D. R., Smith, R. L., Carriere, Y., & Moore Brusca, W. (2018). Molecular phylogeny, ecology and multispecies aggregation behaviour of bombardier beetles in Arizona. PLoS ONE, 13(10), e0205192.
• Wolfin, M. S., Raguso, R. A., Davidowitz, G., & Goyret, J. (2018). Context-dependency of in-flight responses by Manduca sexta moths to ambient differences in relative humidity. Journal of Experimental Biology, 221, jeb177774.
• Wone, B. W., Pathak, J., & Davidowitz, G. (2018). Flight duration and flight muscle ultrastructure of unfed hawk moths. Arthropod Structure and Development.
• Davidowitz, G., McCue, M. D., & Levin, E. (2017). More than just sugar: allocation of nectar amino acids and fatty acids in a Lepidopteran. Proceedings of the Royal Society B, 284, 2016-2126.
• Hatle, J. D., Awan, A., Nicholas, J., Koch, R., Vokrri, J. R., McCue, M. D., Williams, C. M., Davidowitz, G., & Hahn, D. A. (2017). Life-extending dietary restriction and ovariectomy each increase leucine oxidation and alter leucine allocation in grasshoppers. EXPERIMENTAL GERONTOLOGY, 96, 155-161.
• Hatle, J. D., Awan, A., Nicholas, J., Koch, R., Vokrri, J. R., McCue, M. D., Williams, C. M., Davidowitz, G., & Hahn, D. A. (2017). Life-extending dietary restriction and ovariectomy each increase leucine oxidation and alter leucine allocation in grasshoppers. Experimental gerontology, 96, 155-161.
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  Reduced reproduction and dietary restriction each extend lifespan in many animal models, but possible contributions of nutrient oxidation and allocation are largely unknown. Ovariectomy and eating 70% of ad libitum-feeding each extend lifespan in lubber grasshoppers. When feeding levels between the two groups are matched, ovariectomy increases fat and protein storage while dietary restriction reduces fat storage. Because of these disparities in nutrient investment, metabolism may differ between these two life-extending treatments. Therefore, we examined the allocation and organismal oxidation of one representative of each macronutrient class: leucine, oleic acid, and glucose. Ovariectomy and dietary restriction each increased oxidation of dietary leucine. Dietary leucine may play a special role in aging because amino acids stimulate cellular growth. Speeding oxidation of leucine may attenuate cellular growth. Allocation of leucine to muscle was the clearest difference between ovariectomy and dietary restriction in this study. Ovariectomy reduced allocation of leucine to femur muscle, whereas dietary restriction increased allocation of leucine to femur muscle. This allocation likely corresponds to muscle maintenance for locomotion, suggesting dietary restriction increases support for locomotion, perhaps to search for food. Last, ovariectomy decreased oxidation of dietary oleic acid and glucose, perhaps to save them for storage, but the site of storage is unclear. This study suggests that the oxidation of branched-chain amino acids may be an underappreciated mechanism underlying lifespan extension.
• Levin, E., Lopez-Martinez, G., Fane, B. A., & Davidowitz, G. (2017). Hawkmoths use nectar sugar to reduce oxidative damage from flight. Science, in press.
• Levin, E., McCue, M. D., & Davidowitz, G. (2017). More than just sugar: allocation of nectar amino acids and fatty acids in a Lepidopteran. Proceedings. Biological sciences, 284(1848).
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  The ability to allocate resources, even when limited, is essential for survival and fitness. We examine how nutrients that occur in minute amounts are allocated among reproductive, somatic, and metabolic demands. In addition to sugar, flower nectars contain two macronutrients-amino acids and fatty acids. We created artificial nectars spiked with C-labelled amino acids and fatty acids and fed these to adult moths (Manduca sexta: Sphingidae) to understand how they allocate these nutrients among competing sinks (reproduction, somatic tissue, and metabolic fuel). We found that both essential and non-essential amino acids were allocated to eggs and flight muscles and were still detectable in early-instar larvae. Parental-derived essential amino acids were more conserved in the early-instars than non-essential amino acids. All amino acids were used as metabolic fuel, but the non-essential amino acids were oxidized at higher rates than essential amino acids. Surprisingly, the nectar fatty acids were not vertically transferred to offspring, but were readily used as a metabolic fuel by the moth, minimizing losses of endogenous nutrient stores. We conclude that the non-carbohydrate components of nectar may play important roles in both reproductive success and survival of these nectar-feeding animals.
• Levin, E., McCue, M. D., & Davidowitz, G. (2017). Sex differences in the utilization of essential and non-essential amino acids in Lepidoptera. The Journal of experimental biology, 220(Pt 15), 2743-2747.
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  The different reproductive strategies of males and females underlie differences in behavior that may also lead to differences in nutrient use between the two sexes. We studied sex differences in the utilization of two essential amino acids (EAAs) and one non-essential amino acid (NEAA) by the Carolina sphinx moth (). On day one post-eclosion from the pupae, adult male moths oxidized greater amounts of larva-derived AAs than females, and more nectar-derived AAs after feeding. After 4 days of starvation, the opposite pattern was observed: adult females oxidized more larva-derived AAs than males. Adult males allocated comparatively small amounts of nectar-derived AAs to their first spermatophore, but this allocation increased substantially in the second and third spermatophores. Males allocated significantly more adult-derived AAs to their flight muscle than females. These outcomes indicate that adult male and female moths employ different strategies for allocation and oxidation of dietary AAs.
• Levin, E., Mccue, M. D., & Davidowitz, G. (2017). Sex differences in the utilization of essential and non-essential amino acids in Lepidoptera. JOURNAL OF EXPERIMENTAL BIOLOGY, 220(15), 2743-2747.
• Smith, G. P., Johnson, C., Davidowitz, G., & Bronstein, J. (2017). Linkages between nectaring and oviposition preferences of Manduca sexta on two co-blooming Datura species in the Sonoran Desert. Ecological Entomology, 43, 85-92.
• Wilson, K., Tseng, A. S., Potter, K. A., Davidowitz, G., & Hildebrand, J. G. (2017). The effects of the alkaloid scopolamine on the performance and behavior of two caterpillar species. Arthropod-Plant Interactions, 12, 21-29.
• Davidowitz, G. (2016). Endocrine Proxies Can Simplify Endocrine Complexity to Enable Evolutionary Prediction. Integrative and comparative biology, 56(2), 198-206.
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  It is well understood that much of evolutionary change is mediated through the endocrine system with growing interest to identify how this occurs. This however, causes a conflict of sorts. To understand endocrine mechanism, a focus on detail is required. In contrast, to understand evolutionary change, reduction to a few key traits is essential. Endocrine proxies, measurable traits that accurately reflect specific hormonal titers or the timing of specific hormonal events, can reduce endocrine complexity to a few traits that enable predictions of how the endocrine system regulates evolutionary change. In the tobacco hornworm (Manduca sexta, Sphingidae), three endocrine proxies, measured on 5470 individuals, were used to test explicit predictions of how the endocrine system regulates the response to 10 generations of simultaneous selection on body size and development time. The critical weight (CW) reflects the variation in the cessation of juvenile hormone (JH) secretion in the last larval instar, the interval to cessation of growth (ICG) reflects the variation in prothoracicotropic hormone and 20-hydroxyecdysone (20E). Growth rate (GR) reflects the nutrient signaling pathways, primarily the insulin and TOR This is a standard identity similar to DNA signaling pathways. These three endocrine proxies explained 99% and 93% of the variation in body size and development time, respectively, following the 10 generations of simultaneous selection. When the two focal traits, body size and development time, were selected in the same direction, both to either increase or both to decrease, the response to selection was determined primarily by the CW and the ICG, proxies for the developmental hormones JH and 20E, and constrained by GR. In contrast, when the two focal traits were selected in opposite directions, one to increase and the other to decrease, the response to selection was determined primarily by the insulin and TOR signaling pathways as measured by their proxy, GR, and constrained by the CW and the ICG. Thus, the use of endocrine proxies may be a powerful tool to reduce endocrine complexity to enable explicit and testable predictions how the endocrine system can enable or constrain evolutionary change.
• Davidowitz, G., Roff, D., & Nijhout, F. (2016). Synergism and antagonism of the proximate mechanisms enables and constrains the response to multivariate simultaneous selection: an empirical test using experimental evolution. American Naturalist.
• Davidowitz, G., Roff, D., & Nijhout, H. F. (2016). Synergism and Antagonism of Proximate Mechanisms Enable and Constrain the Response to Simultaneous Selection on Body Size and Development Time: An Empirical Test Using Experimental Evolution. The American naturalist, 188(5), 499-520.
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  Natural selection acts on multiple traits simultaneously. How mechanisms underlying such traits enable or constrain their response to simultaneous selection is poorly understood. We show how antagonism and synergism among three traits at the developmental level enable or constrain evolutionary change in response to simultaneous selection on two focal traits at the phenotypic level. After 10 generations of 25% simultaneous directional selection on all four combinations of body size and development time in Manduca sexta (Sphingidae), the changes in the three developmental traits predict 93% of the response of development time and 100% of the response of body size. When the two focal traits were under synergistic selection, the response to simultaneous selection was enabled by juvenile hormone and ecdysteroids and constrained by growth rate. When the two focal traits were under antagonistic selection, the response to selection was due primarily to change in growth rate and constrained by the two hormonal traits. The approach used here reduces the complexity of the developmental and endocrine mechanisms to three proxy traits. This generates explicit predictions for the evolutionary response to selection that are based on biologically informed mechanisms. This approach has broad applicability to a diverse range of taxa, including algae, plants, amphibians, mammals, and insects.
• Hood-Nowotny, R., Mayr, L., Heindler, J., Saad, N., Seth, R., Davidowitz, G., & Simmons, G. (2016). Towards incorporating insect isotope analysis using cavity ring-down spectroscopy into area-wide insect pest management programs. Florida Entomologist, 99, 177-184.
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  Hood-Nowotny, R., L. Mayr, J. Heindler, N. Saad, R. Seth, G. Davidowitz, G. Simmons. (2015). Insect isotope analysis using cavity ring-down spectroscopy: Moving towards incorporating isotope analysis into area-wide management program. Florida Entomologist (in press).
• Levin, E., Mitra, C., & Davidowitz, G. (2016). Fed males increase oviposition in female hawkmoths via non-nutritive direct benefits. ANIMAL BEHAVIOUR, 112, 111-118.
• Mitra, C., Reynoso, E., Davidowitz, G., & Papaj, D. (2016). Effects of sodium puddling on male mating success, courtship and flight in a swallowtail butterfly. ANIMAL BEHAVIOUR, 114, 203-210.
• Mitra, C., Reynoso, E., Davidowitz, G., & Papaj, D. (2016). Effects of sodium puddling on male mating success, courtship and flight in a swallowtail butterfly. Animal behaviour, 114, 203-210.
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  In many Lepidoptera species usually only males puddle for sodium. Two explanations have been offered for this: (1) neuromuscular activity: males need increased sodium for flight because they are more active flyers than females; and (2) direct benefits: sodium is a type of direct benefit provided by males to females via ejaculate during mating. Surprisingly, there is little direct experimental evidence for either of these. In this study, we examined both explanations using the pipevine swallowtail butterfly, L. If sodium increases neuromuscular activity, males consuming sodium should be better fliers than males without sodium. If males collect sodium for nuptial gifts that benefit their mates, males consuming sodium may have greater mating success than males without sodium. In that case, females then need an honest cue/signal of the quality of male-provided direct benefits that they can assess before mating. If sodium affects male courtship flight by increasing neuromuscular activity, how a male courts could serve as such a premating cue/signal of male benefit quality. Therefore, sodium may benefit males in terms of obtaining mates by increasing their neuromuscular activity. In this study we found that males that consumed sodium courted more vigorously and had greater mating success than males that consumed water. In addition, the courtship displays of males consuming sodium were significantly different from those of males consuming water, providing a possible honest cue/signal of male benefit quality that females can assess. Interestingly, we did not find evidence that sodium consumption affects male flight outside of courtship. That only aspects of male flight related to mating were affected by sodium, while aspects of general flight were not, is consistent with the idea that sodium may benefit males in terms of obtaining mates via effects on neuromuscular activity.
• Wilson, J. K., Tseng, A. S., Potter, K. A., Davidowitz, G., & Hildebrand, J. G. (2016). The effects of the alkaloid scopolamine on the performance and behavior of two caterpillar species. Arthropod-Plant Interactions.
• Helm, B. R., & Davidowitz, G. (2015). Evidence of a hemolymph-born factor that induces onset of maturation in Manduca sexta larvae. Journal of Insect Physiology, 78, 78-86.
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  Helm, B.R., and G. Davidowitz. (2015). Evidence of a hemolymph-born factor that induces onset of maturation in Manduca sexta larvae Journal of Insect Physiology 78:78-86.
• McCue, M. D., Guzman, R. M., Passement, C. A., & Davidowitz, G. (2015). How and When Do Insects Rely on Endogenous Protein and Lipid Resources during Lethal Bouts of Starvation? A New Application for 13C-Breath testing. PloS one, 10(10), e0140053.
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  Most of our understanding about the physiology of fasting and starvation comes from studies of vertebrates; however, for ethical reasons, studies that monitor vertebrates through the lethal endpoint are scant. Insects are convenient models to characterize the comparative strategies used to cope with starvation because they have diverse life histories and have evolved under the omnipresent challenge of food limitation. Moreover, we can study the physiology of starvation through its natural endpoint. In this study we raised populations of five species of insects (adult grasshoppers, crickets, cockroaches, and larval beetles and moths) on diets labeled with either 13C-palmitic acid or 13C-leucine to isotopically enrich the lipids or the proteins in their bodies, respectively. The insects were allowed to become postabsorptive and then starved. We periodically measured the δ13C of the exhaled breath to characterize how each species adjusted their reliance on endogenous lipids and proteins as energy sources. We found that starving insects employ a wide range of strategies for regulating lipid and protein oxidation. All of the insects except for the beetle larvae were capable of sharply reducing reliance on protein oxidation; however, this protein sparing strategy was usually unsustainable during the entire starvation period. All insects increased their reliance on lipid oxidation, but while some species (grasshoppers, cockroaches, and beetle larvae) were still relying extensively on lipids at the time of death, other species (crickets and moth larvae) allowed rates of lipid oxidation to return to prestarvation levels. Although lipids and proteins are critical metabolic fuels for both vertebrates and insects, insects apparently exhibit a much wider range of strategies for rationing these limited resources during starvation.
• McCue, M., McCue, M., Guzman, R. M., Guzman, R. M., Passement, C. A., Passement, C. A., Davidowitz, G., & Davidowitz, G. (2015). How do insects rely on endogenous protein and lipid resources during lethal bouts of starvation? A new application for 13C-breath testing. PLoS ONE, e0140053. doi:10.1371/journal.pone.0140053
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  McCue, M., R.M. Guzman, C. A. Passement, G. Davidowitz. (2015). How and when do insects rely on endogenous protein and lipid resources during lethal bouts of starvation? A new application for 13C-breath testing. PLoS ONE 10(10): e0140053. doi:10.1371/journal.pone.0140053.
• Arcas, S., Davidowitz, G., & Contreras, H. (2014). Feeding on the wing: energy allocation and prioritization in the hawk moth Manduca sexta. FASEB JOURNAL, 28(1, S).
• Stillwell, R. C., Daws, A., & Davidowitz, G. (2014). The Ontogeny of Sexual Size Dimorphism of a Moth: When Do Males and Females Grow Apart?. PLOS ONE, 9(9).
• Stillwell, R. C., Daws, A., & Davidowitz, G. (2014). The ontogeny of sexual size dimorphism of a moth: when do males and females grow apart?. PLoS ONE, 9, e106548.
• Stillwell, R. C., Daws, A., & Davidowitz, G. (2014). The ontogeny of sexual size dimorphism of a moth: when do males and females grow apart?. PloS one, 9(9), e106548.
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  Sexual dimorphism in body size (sexual size dimorphism) is common in many species. The sources of selection that generate the independent evolution of adult male and female size have been investigated extensively by evolutionary biologists, but how and when females and males grow apart during ontogeny is poorly understood. Here we use the hawkmoth, Manduca sexta, to examine when sexual size dimorphism arises by measuring body mass every day during development. We further investigated whether environmental variables influence the ontogeny of sexual size dimorphism by raising moths on three different diet qualities (poor, medium and high). We found that size dimorphism arose during early larval development on the highest quality food treatment but it arose late in larval development when raised on the medium quality food. This female-biased dimorphism (females larger) increased substantially from the pupal-to-adult stage in both treatments, a pattern that appears to be common in Lepidopterans. Although dimorphism appeared in a few stages when individuals were raised on the poorest quality diet, it did not persist such that male and female adults were the same size. This demonstrates that the environmental conditions that insects are raised in can affect the growth trajectories of males and females differently and thus when dimorphism arises or disappears during development. We conclude that the development of sexual size dimorphism in M. sexta occurs during larval development and continues to accumulate during the pupal/adult stages, and that environmental variables such as diet quality can influence patterns of dimorphism in adults.
• Thaler, J. S., Contreras, H., & Davidowitz, G. (2014). Effects of predation risk and plant resistance on Manduca sexta caterpillar feeding behaviour and physiology. ECOLOGICAL ENTOMOLOGY, 39(2), 210-216.
• Wone, B., Ojha, J., Contreras, H., & Davidowitz, G. (2014). More is not always better: a hidden cost of the flight-fecundity trade-off in the hawk moth, Manduca sexta. FASEB JOURNAL, 28(1, S).
• Contreras, H. L., Goyret, J., Arx, M., Pierce, C. T., Bronstein, J. L., Raguso, R. A., & Davidowitz, G. (2013). The effect of ambient humidity on the foraging behavior of the hawkmoth Manduca sexta. JOURNAL OF COMPARATIVE PHYSIOLOGY A-NEUROETHOLOGY SENSORY NEURAL AND BEHAVIORAL PHYSIOLOGY, 199(11, SI), 1053-1063.
• Davidowitz, G., Contreras, H. L., Goyret, J., von Arx, M., Pierce, C. T., Bronstein, J. L., Raguso, R. A., & Davidowitz, G. -. (2013). The effect of ambient humidity on the foraging behavior of the hawkmoth Manduca sexta. Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology, 199(11).
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  The foraging decisions of flower-visiting animals are contingent upon the need of an individual to meet both energetic and osmotic demands. Insects can alter their food preferences to prioritize one need over the other, depending on environmental conditions. In this study, preferences in nectar sugar concentrations (0, 12, 24 %) were tested in the hawkmoth Manduca sexta, in response to different levels of ambient humidity (20, 40, 60, and 80 % RH). Moths altered their foraging behavior when placed in low humidity environments by increasing the volume of nectar imbibed and by consuming more dilute nectar. When placed in high humidity environments the total volume imbibed decreased, because moths consumed less from dilute nectars (water and 12 % sucrose). Survivorship was higher with higher humidity. Daily foraging patterns changed with relative humidity (RH): moths maximized their nectar consumption earlier, at lower humidities. Although ambient humidity had an impact on foraging activity, activity levels and nectar preferences, total energy intake was not affected. These results show that foraging decisions made by M. sexta kept under different ambient RH levels allow individuals to meet their osmotic demands while maintaining a constant energy input.
• Fitzpatrick, G., Davidowitz, G. -., & Bronstein, J. -. (2013). An herbivore's thermal tolerance is higher than that of the ant defenders in a desert protection mutualism. Sociobiology, 60, 252-258.
• Harrison, J. F., Cease, A. J., VandenBrooks, J. M., Albert, T., & Davidowitz, G. (2013). Caterpillars selected for large body size and short development time are more susceptible to oxygen-related stress. ECOLOGY AND EVOLUTION, 3(5), 1305-1316.
• Harrison, J. F., Cease, A. J., Vandenbrooks, J. M., Albert, T., & Davidowitz, G. (2013). Caterpillars selected for large body size and short development time are more susceptible to oxygen-related stress. Ecology and Evolution, 3(5), 1305-1316.
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  PMID: 23762517;PMCID: PMC3678485;Abstract: Recent studies suggest that higher growth rates may be associated with reduced capacities for stress tolerance and increased accumulated damage due to reactive oxygen species. We tested the response of Manduca sexta (Sphingidae) lines selected for large or small body size and short development time to hypoxia (10 kPa) and hyperoxia (25, 33, and 40 kPa); both hypoxia and hyperoxia reduce reproduction and oxygen levels over 33 kPa have been shown to increase oxidative damage in insects. Under normoxic (21 kPa) conditions, individuals from the large-selected (big-fast) line were larger and had faster growth rates, slightly longer developmental times, and reduced survival rates compared to individuals from a line selected for small size (small-fast) or an unselected control line. Individuals from the big-fast line exhibited greater negative responses to hyperoxia with greater reductions in juvenile and adult mass, growth rate, and survival than the other two lines. Hypoxia generally negatively affected survival and growth/size, but the lines responded similarly. These results are mostly consistent with the hypothesis that simultaneous acquisition of large body sizes and short development times leads to reduced capacities for coping with stressful conditions including oxidative damage. This result is of particular importance in that natural selection tends to decrease development time and increase body size. © 2013 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
• Harrison, J. F., Cease, A., VandenBrooks, J. M., Albert, T., Pierce, N., & Davidowitz, G. -. (2013). Caterpillars selected for large body size and short development time are more susceptible to oxygen-related stress. Ecology and Evolution, 3, 1305-1316.
• Helm, B. R., & Davidowitz, G. (2013). Mass and volume growth of an insect tracheal system within a single instar. JOURNAL OF EXPERIMENTAL BIOLOGY, 216(24), 4703-4711.
• Helm, B. R., & Davidowitz, G. (2013). Mass and volume growth of an insect tracheal system within a single instar. Journal of Experimental Biology, 216(24), 4703-4711.
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  Abstract: Organisms must accommodate oxygen delivery to developing tissues as body mass increases during growth. In insects, the growth of the respiratory system has been assumed to occur only during molts, whereas body mass and volume increase during the larval stages between molts. This decouples whole-body growth from the growth of the oxygen supply system. This assumption is derived from the observation that the insect respiratory system is an invagination of the exoskeleton, which must be shed during molts for continued growth to occur. Here, we provide evidence that this assumption is incorrect. We found that the respiratory system increases substantially in both mass and volume within the last larval instar of Manduca sexta larvae, and that the growth of the respiratory system changes with diet quality, potentially as a consequence of shifting metabolic demands. © 2013. Published by The Company of Biologists Ltd.
• Helm, B. R., & Davidowitz, G. -. (2013). Mass and volume growth of larval insect tracheal system within a single instar. The Journal of experimental biology.
• Miranda, V. A., Navarro, P. D., Davidowitz, G. -., Bronstein, J. -., & Stock, S. P. (2015). The effect of insect host age and diet on the fitness of the entomopathogenic nematode - bacteria mutualism. Symbiosis. Symbiosis, 61, 145-153. doi:DOI 10.1007/s13199-013-0266-7
• Miranda, V. A., Navarro, P. D., Davidowitz, G., Bronstein, J., & Stock, S. P. (2013). Effect of insect host age and diet on the fitness of the entomopathogenic nematode-bacteria mutualism. SYMBIOSIS, 61(3), 145-153.
• Ojha, J., & Davidowitz, G. (2013). Absence of reproductive organs increases somatic maintenance in the Hawk moth, Manduca sexta. FASEB JOURNAL, 27.
• Snell-Rood, E. C., Davidowitz, G. -., & Papaj, D. R. (2013). Plasticity in learning causes immediate and trans-generational changes in allocation of resources. Integrative and Comparative Biology, 53, 329-339.
• Snell-Rood, E. C., Davidowitz, G., & Papaj, D. R. (2013). Plasticity in learning causes immediate and trans-generational changes in allocation of resources. Integrative and comparative biology, 53(2), 329-39.
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  Plasticity in the development and expression of behavior may allow organisms to cope with novel and rapidly changing environments. However, plasticity itself may depend on the developmental experiences of an individual. For instance, individuals reared in complex, enriched environments develop enhanced cognitive abilities as a result of increased synaptic connections and neurogenesis. This suggests that costs associated with behavioral plasticity-in particular, increased investment in "self" at the expense of reproduction-may also be flexible. Using butterflies as a system, this work tests whether allocation of resources changes as a result of experiences in "difficult" environments that require more investment in learning. We contrast allocation of resources among butterflies with experience in environments that vary in the need for learning. Butterflies with experience searching for novel (i.e., red) hosts, or searching in complex non-host environments, allocate more resources (protein and carbohydrate reserves) to their own flight muscle. In addition, butterflies with experience in these more difficult environments allocate more resources per individual offspring (i.e., egg size and/or lipid reserves). This results in a mother's experience having significant effects on the growth of her offspring (i.e., dry mass and wing length). A separate study showed this re-allocation of resources comes at the expense of lifetime fecundity. These results suggest that investment in learning, and associated changes in life history, can be adjusted depending on an individual's current need, and their offspring's future needs, for learning.
• Stock, S. P., Miranda, V., Navarro, P., Davidowitz, G. -., & Bronstein, J. -. (2013). Effect of insect host age and diet on the fitness of the entomopathogenic nematode-bacteria mutualism.. Symbiosis, DOI 10.1007/s13199-013-0266-7.(61), 145-153.
• Thaler, J. S., Contreras, H., & Davidowitz, G. -. (2013). Effects of predation risk and plant resistance on Manduca sexta caterpillar feeding behavior and physiology. Ecological Entomology.
• Arx, M. V., Goyret, J., Davidowitz, G., & Raguso, R. A. (2012). Floral humidity as a reliable sensory cue for profitability assessment by nectar-foraging hawkmoths. Proceedings of the National Academy of Sciences of the United States of America, 109(24), 9471-9476.
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  PMID: 22645365;PMCID: PMC3386090;Abstract: Most research on plant-pollinator communication has focused on sensory and behavioral responses to relatively static cues. Floral rewards such as nectar, however, are dynamic, and foraging animals will increase their energetic profit if they can make use of floral cues that more accurately indicate nectar availability. Here we document such a cue-transient humidity gradients-using the night blooming flowers of Oenothera cespitosa (Onagraceae). The headspace of newly opened flowers reaches levels of about 4% above ambient relative humidity due to additive evapotranspirational water loss through petals and water-saturated air from the nectar tube. Floral humidity plumes differ from ambient levels only during the first 30 min after anthesis (before nectar is depleted in wild populations), whereas other floral traits (scent, shape, and color) persist for 12-24 h. Manipulative experiments indicated that floral humidity gradients are mechanistically linked to nectar volume and therefore contain information about energy rewards to floral visitors. Behavioral assays with Hyles lineata (Sphingidae) and artificial flowers with appropriate humidity gradients suggest that these hawkmoth pollinators distinguish between subtle differences in relative humidity when other floral cues are held constant. Moths consistently approached and probed flowers with elevated humidity over those with ambient humidity levels. Because floral humidity gradients are largely produced by the evaporation of nectar itself, they represent condition-informative cues that facilitate remote sensing of floral profitability by discriminating foragers. In a xeric environment, this level of honest communication should be adaptive when plant reproductive success is pollinator limited, due to intense competition for the attention of a specialized pollinator.
• Barron-Gafford, G. A., Rascher, U., Bronstein, J. L., Davidowitz, G., Chaszar, B., & Huxman, T. E. (2012). Herbivory of wild Manduca sexta causes fast down-regulation of photosynthetic efficiency in Datura wrightii: an early signaling cascade visualized by chlorophyll fluorescence. Photosynthesis research, 113(1-3), 249-60.
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  Plants experiencing herbivory suffer indirect costs beyond direct loss of leaf area, but differentially so based on the herbivore involved. We used a combination of chlorophyll fluorescence imaging and gas exchange techniques to quantify photosynthetic performance, the efficiency of photochemistry, and heat dissipation to examine immediate and longer-term physiological responses in the desert perennial Datura wrightii to herbivory by tobacco hornworm, Manduca sexta. Herbivory by colony-reared larvae yielded no significant reduction in carbon assimilation, whereas herbivory by wild larvae induced a fast and spreading down-regulation of photosynthetic efficiency, resulting in significant losses in carbon assimilation in eaten and uneaten leaves. We found both an 89 % reduction in net photosynthetic rates in herbivore-damaged leaves and a whole-plant response (79 % decrease in undamaged leaves from adjacent branches). Consequently, herbivory costs are higher than previously estimated in this well-studied plant-insect interaction. We used chlorophyll fluorescence imaging to elucidate the mechanisms of this down-regulation. Quantum yield decreased up to 70 % in a small concentric band surrounding the feeding area within minutes of the onset of herbivory. Non-photochemical energy dissipation by the plant to avoid permanent damage was elevated near the wound, and increased systematically in distant areas of the leaf away from the wound over subsequent hours. Together, the results underscore not only potential differences between colony-reared and wild-caught herbivores in experimental studies of herbivory but also the benefits of quantifying physiological responses of plants in unattacked leaves.
• Barron-Gafford, G., Rascher, U., Bronstein, J., Davidowitz, G., Chaszar, B., & Huxman, T. (2012). Herbivory of wild Manduca sexta causes fast down-regulation of photosynthetic efficiency in Datura wrightii: an early signaling cascade visualized by chlorophyll fluorescence. Photosynthesis Research, 113, 249-260.
• Davidowitz, G., Nijhout, H. F., & Roff, D. A. (2012). Predicting the response to simultaneous selection: genetic architecture and physiological constraints. Evolution; international journal of organic evolution, 66(9), 2916-28.
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  A great deal is known about the evolutionary significance of body size and development time. They are determined by the nonlinear interaction of three physiological traits: two hormonal events and growth rate (GR). In this study we investigate how the genetic architecture of the underlying three physiological traits affects the simultaneous response to selection on the two life-history traits in the hawkmoth Manduca sexta. The genetic architecture suggests that when the two life-history traits are both selected in the same direction (to increase or decrease) the response to selection is primarily determined by the hormonal mechanism. When the life-history traits are selected in opposite directions (one to increase and one to decrease) the response to selection is primarily determined by factors that affect the GR. To determine how the physiological traits affect the response to selection of the life-history traits, we simulated the predicted response to 10 generations of selection. A total of 83% of our predictions were supported by the simulation. The main components of this physiological framework also exist in unicellular organisms, vertebrates, and plants and can thus provide a robust framework for understanding how underlying physiology can determine the simultaneous evolution of life-history traits.
• Davidowitz, G., Nijhout, H., & Roff, D. (2012). Predicting the response to simultaneous selection: genetic architecture and physiological constraints. Evolution, 66, 2916-2928.
• Potter, K., Bronstein, J. -., & Davidowitz, G. -. (2012). Choice of oviposition sites by Manduca sexta and its consequences for egg and larval performance. Entomologia Experimentalis et Applicata, 144, 286-293.
• Von, A. M., Goyret, J., Davidowitz, G., & Raguso, R. (2012). Floral humidity as a reliable sensory cue for profitability assessment by nectar-foraging hawkmoths. Proceedings of the National Academy of Sciences USA, 109, 9471-9476.
• Potter, K. A., Davidowitz, G., & Woods, H. A. (2011). Cross-stage consequences of egg temperature in the insect Manduca sexta. Functional Ecology, 25(3), 548-556.
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  Abstract: An organism's environment, particularly early in development, can profoundly shape its future phenotypes. While the long-term consequences of embryonic temperature are well studied in vertebrates, insects have complex life cycles that may uncouple temperature's effects in one stage from physiology in the next. This study examines how egg temperature affects insect performance across all subsequent life stages. We focused on the hawkmoth, Manduca sexta, and examined how egg temperatures affected hatching time, hatchling mass, larval growth, development time, head capsule size, pupal mass and adult fecundity. Eggs were exposed to either diurnal temperature cycles or a single heat shock; in both experiments, temperatures were within the range to which eggs are typically exposed in the field. Although the consequences of egg temperature varied depending on the type of treatment, both cycling temperatures and heat shock affected egg development time and initial larval growth rate, which likely have fitness consequences for M. sexta in nature. In contrast, egg temperature had no persistent effect on any trait measured in later larval stages, pupae or adults. Organisms with complex life cycles -Manduca has four distinct life stages and multiple larval sub-stages - may benefit from rapid compensation for poor early conditions. Additionally, the modularity of insect life cycles may help insects cope with environmental variability by insulating later stages from disturbances during embryogenesis. © 2010 The Authors. Functional Ecology © 2010 British Ecological Society.
• Potter, K., Davidowitz, G., & Woods, H. (2011). Cross-stage consequences of egg temperature in the insect Manduca sexta. Functional Ecology, 25, 548-556.
• Snell-Rood, E. C., Davidowitz, G., & Papaj, D. R. (2011). Reproductive tradeoffs of learning in a butterfly. BEHAVIORAL ECOLOGY, 22(2), 291-302.
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  Abstract: The evolution of learning has long been hypothesized to be limited by fitness trade-offs such as delays in reproduction. We explored the relationship between host learning and reproduction in the cabbage white butterfly, Pieris rapae. The cabbage white female is innately biased to search for common green hosts but can learn to search for rare red hosts. Host learning was shown previously to vary among full-sibling families and to incur costs in terms of host search efficiency and brain size. In the present study, we show that butterflies from full-sib families with relatively better learning performance on red hosts tend to emerge as adults with relatively fewer and less-developed eggs. We also used methoprene, a juvenile hormone mimic, to advance reproduction in female cabbage whites. We found that methoprene-treated butterflies improved host-finding ability less with experience, relative to controls, providing independent evidence of a link between learning and timing of reproduction. Finally, we show that the learning experience itself is associated with additional decreases in lifetime fecundity. These results support a range of theoretical and comparative studies highlighting the importance of fitness tradeoffs in the evolution of learning and cognition. © 2011 The Author.
• Snell-Rood, E. C., Davidowitz, G., & Papaj, D. R. (2011). Reproductive tradeoffs of learning in a butterfly. Behavioral Ecology, 22(2), 291-302.
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  Abstract: The evolution of learning has long been hypothesized to be limited by fitness trade-offs such as delays in reproduction. We explored the relationship between host learning and reproduction in the cabbage white butterfly, Pieris rapae. The cabbage white female is innately biased to search for common green hosts but can learn to search for rare red hosts. Host learning was shown previously to vary among full-sibling families and to incur costs in terms of host search efficiency and brain size. In the present study, we show that butterflies from full-sib families with relatively better learning performance on red hosts tend to emerge as adults with relatively fewer and less-developed eggs. We also used methoprene, a juvenile hormone mimic, to advance reproduction in female cabbage whites. We found that methoprene-treated butterflies improved host-finding ability less with experience, relative to controls, providing independent evidence of a link between learning and timing of reproduction. Finally, we show that the learning experience itself is associated with additional decreases in lifetime fecundity. These results support a range of theoretical and comparative studies highlighting the importance of fitness tradeoffs in the evolution of learning and cognition. © 2011 The Author.
• Snell-Rood, E., Davidowitz, G., & Papaj, D. (2011). Reproductive tradeoffs of learning in a butterfly. Behavioral Ecology, 22, 291-302.
• Alarcon, R., Riffell, J. A., Davidowitz, G. -., Hildebrand, J. G., & Bronstein, J. -. (2010). Sex-dependent variation in the floral preferences of the hawkmoth Manduca sexta. Animal Behavior, 80, 289-296.
• Davidowitz, G. -., Nijhout, H. F., & Roff, D. A. (2010). Conflicting processes in the evolution of body size and development time. Philosophical Transactions of the Royal Society B, 365, 567-575.
• Davidowitz, G., Davidowitz, G. -., & Stillwell, R. C. (2010). Sex differences in phenotypic plasticity of a mechanism that controls body size: implications for sexual size dimorphism. Proceedings. Biological sciences / The Royal Society, 277(1701).
• Davidowitz, G., Stillwell, R. C., & Davidowitz, G. -. (2010). A developmental perspective on the evolution of sexual size dimorphism of a moth. Proceedings. Biological sciences / The Royal Society, 277(1690).
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  Males and females of almost all organisms exhibit sexual differences in body size, a phenomenon called sexual size dimorphism (SSD). How the sexes evolve to be different sizes, despite sharing the same genes that control growth and development, and hence a common genetic architecture, has remained elusive. Here, we show that the genetic architecture (heritabilities and genetic correlations) of the physiological mechanism that regulates size during the last stage of larval development of a moth, differs between the sexes, and thus probably facilitates, rather than hinders, the evolution of SSD. We further show that the endocrine system plays a critical role in generating SSD. Our results demonstrate that knowledge of the genetic architecture underlying the physiological process during development that ultimately produces SSD in adults can elucidate how males and females of organisms evolve to be of different sizes.
• Nijhout, H. F., Roff, D. A., & Davidowitz, G. (2010). Conflicting processes in the evolution of body size and development time. Philosophical Transactions of the Royal Society B: Biological Sciences, 365(1540), 567-575.
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  PMID: 20083633;PMCID: PMC2817141;Abstract: Body size and development time of Manduca sexta are both determined by the same set of three developmental-physiological factors. These define a parameter space within which it is possible to analyse and explain how phenotypic change is associated with changes in the underlying factors. Body size and development time are determined by the identical set of underlying factors, so they are not independent, but because the mechanisms by which these factors produce each phenotype are different, the two phenotypes are only weakly correlated, and the correlation is context dependent. We use a mathematical model of this mechanism to explore the association between body size and development time and show that the correlation between these two life-history traits can be positive, zero or negative, depending entirely on where in parameter space a population is located, and on which of the underlying factors has a greater variation. The gradient within this parameter space predicts the unconstrained evolutionary trajectory under directional selection on each trait. Calculations of the gradients for body size and development time revealed that these are nearly orthogonal through much of the parameter space. Therefore, simultaneous directional selection on body size and development time can be neither synergistic nor antagonistic but leads to conflicting selection on the underlying developmental parameters. © 2010 The Royal Society.
• Stillwell, R. C., & Davidowitz, G. (2010). A developmental perspective on the evolution of sexual size dimorphism of a moth. Proceedings of the Royal Society B: Biological Sciences, 277(1690), 2069-2074.
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  PMID: 20219738;PMCID: PMC2880092;Abstract: Males and females of almost all organisms exhibit sexual differences in body size, a phenomenon called sexual size dimorphism (SSD). How the sexes evolve to be different sizes, despite sharing the same genes that control growth and development, and hence a common genetic architecture, has remained elusive. Here, we show that the genetic architecture (heritabilities and genetic correlations) of the physiological mechanism that regulates size during the last stage of larval development of a moth, differs between the sexes, and thus probably facilitates, rather than hinders, the evolution of SSD. We further show that the endocrine system plays a critical role in generating SSD. Our results demonstrate that knowledge of the genetic architecture underlying the physiological process during development that ultimately produces SSD in adults can elucidate how males and females of organisms evolve to be of different sizes. © 2010 The Royal Society.
• Stillwell, R. C., & Davidowitz, G. (2010). Sex differences in phenotypic plasticity of a mechanism that controls body size: Implications for sexual size dimorphism. Proceedings of the Royal Society B: Biological Sciences, 277(1701), 3819-3826.
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  PMID: 20610429;PMCID: PMC2992702;Abstract: The degree and/or direction of sexual size dimorphism (SSD) varies considerably among species and among populations within species. Although this variation is in part genetically based, much of it is probably due to the sexes exhibiting differences in body size plasticity. Here, we use the hawkmoth Manduca sexta, to test the hypothesis that moths reared on different diet qualities and at different temperatures will exhibit sex-specific body size plasticity. In addition, we explore the proximate mechanisms that potentially create sex-specific plasticity by examining three physiological variables known to regulate body size in this insect: the growth rate, the critical weight (which measures the cessation of juvenile hormone secretion from the corpora allata) and the interval to cessation of growth (ICG; which measures the time interval between the critical weight and the secretion of the ecdysteroids that regulate pupation and metamorphosis). We found that peak larval mass of males and females did not exhibit sex-specific plasticity in response to diet or temperature. However, the sexes did exhibit sex-specific plasticity in the mechanism that controls size; males and females exhibited sex-specific plasticity in the growth rate and the critical weight in response to both diet and temperature, whereas the ICG only exhibited sex-specific plasticity in response to diet. Our results suggest it is important for the sexes to maintain the same degree of SSD across environments and that this is accomplished by the sexes exhibiting differential sensitivity of the physiological factors that determine body size to environmental variation. © 2010 The Royal Society.
• Stillwell, R. C., Blanckenhorn, W. U., Teder, T., Davidowitz, G., & Fox, C. W. (2010). Sex differences in phenotypic plasticity affect variation in sexual size dimorphism in insects: From physiology to evolution. Annual Review of Entomology, 55, 227-245.
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  PMID: 19728836;Abstract: Males and females of nearly all animals differ in their body size, a phenomenon called sexual size dimorphism (SSD). The degree and direction of SSD vary considerably among taxa, including among populations within species. A considerable amount of this variation is due to sex differences in body size plasticity. We examine how variation in these sex differences is generated by exploring sex differences in plasticity in growth rate and development time and the physiological regulation of these differences (e.g., sex differences in regulation by the endocrine system). We explore adaptive hypotheses proposed to explain sex differences in plasticity, including those that predict that plasticity will be lowest for traits under strong selection (adaptive canalization) or greatest for traits under strong directional selection (condition dependence), but few studies have tested these hypotheses. Studies that combine proximate and ultimate mechanisms offer great promise for understanding variation in SSD and sex differences in body size plasticity in insects. © 2010 by Annual Reviews All rights reserved.
• Stillwell, R. C., Blanckenhorn, W., Teder, T., Davidowitz, G. -., & FOX, C. W. (2010). Sex differences in phenotypic plasticity of body size and variation in sexual size dimorphism – from physiology to ecology. Annual Review of Entomology, 55, 227-245.
• Davidowitz, G. (2009). Ecological Developmental Biology: Integrating Epigenetics, Medicine and Evolution. Scott F. Gilbert and David Epel.. Integrative and Comparative Biology, 49(6), 727-729. doi:10.1093/icb/icp106
• Davidowitz, G. -. (2009). Insect eggs protected from high temperatures by limited homeothermy of plant leaves. Journal of Experimental Biology, 212, 3448-3454.
• Davidowitz, G., Bronstein, J. L., Huxman, T., Horvath, B., Farabee, M., & Davidowitz, G. -. (2009). Reproductive biology of Datura wrightii: the benefits of a herbivorous pollinator. Annals of botany, 103(9).
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  A deeper understanding of mutualism can be reached by studying systems with measurable costs and benefits. Most studies of this type focus on an unusual class of obligate, species-specific pollination mutualisms. The interaction between Datura wrightii (Solanaceae) and the hawkmoth Manduca sexta offers similar advantages but greater generality. Adult moths both nectar at and deposit eggs on the same plant; larvae are herbivorous. The antagonistic component of this interaction has been well studied. Here the role of M. sexta as a pollinator of D. wrightii, particularly in the context of this moth's frequent nectaring visits to the bat-pollinated plant Agave palmeri, is documented.
• Potter, K., Davidowitz, G., & Woods, H. A. (2009). Insect eggs protected from high temperatures by limited homeothermy of plant leaves. Journal of Experimental Biology, 212(21), 3448-3454.
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  PMID: 19837886;Abstract: Virtually all aspects of insect biology are affected by body temperature, and many taxa have evolved sophisticated temperaturecontrol mechanisms. All insects, however, begin life as eggs and lack the ability to thermoregulate. Eggs laid on leaves experience a thermal environment, and thus a body temperature, that is strongly influenced by the leaves themselves. Because plants can maintain leaf temperatures that differ from ambient, e.g. by evapotranspiration, plant hosts may protect eggs from extreme ambient temperatures. We examined the degree to which leaves buffer ambient thermal variation and whether that buffering benefits leaf-associated insect eggs. In particular, we: (1) measured temperature variation at oviposition sites in the field, (2) manipulated temperatures in the laboratory to determine the effect of different thermal conditions on embryo development time and survival, and (3) tested embryonic metabolic rates over increasing temperatures. Our results show that Datura wrightii leaves buffer Manduca sexta eggs from fatally high ambient temperatures in the southwestern USA. Moreover, small differences in temperature profiles among leaves can cause large variation in egg metabolic rate and development time. Specifically, large leaves were hotter than small leaves during the day, reaching temperatures that are stressfully high for eggs. This study provides the first mechanistic demonstration of how this type of leaf-constructed thermal refuge interacts with egg physiology.
• Davidowitz, G. (2008). Population and environmental effects on the size-fecundity relationship in a common grasshopper across an aridity gradient. Journal of Orthoptera Research, 17(2), 265-271. doi:10.1665/1082-6467-17.2.265
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  Abstract Body size is of primary interest to biologists because of its often positive correlation with fitness, in particular fecundity. The size-fecundity relationship is well established both within and among species. However, little is known about how the size-fecundity relationship differs among populations of the same species or whether it differs in response to environmental conditions experienced by a single population. This study examines the size-fecundity relationship in the pallid-winged grasshopper (Trimerotropis pallidipennis: Acrididae, Oedipodinae) among seven populations that extend along an aridity gradient in the southwestern United States. Results showed a positive relationship between body size of field-caught females and precipitation along the gradient, but only among those populations that receive less than 12 cm rainfall a year. There was a positive relationship between body size and the number of mature oocyte in the ovaries and with the number of hatchlings. Potential fecundity, ...
• Davidowitz, G., Bronstein, J. L., Alarcon, R., & Alarcn, R. (2008). Nectar usage in a southern Arizona hawkmoth community. Ecological Entomology, 33(4), 503-509. doi:10.1111/j.1365-2311.2008.00996.x
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  1. Hawkmoths (Sphingidae) are important plant associates at two life-history stages: larvae are herbivorous, whereas adults are nectar feeders and often pollinators. The diversity and identities of plants used for nectar is poorly known, however. 2. This study takes a community-level approach to hawkmoth nectar plant usage in a semi-arid grassland habitat in southern Arizona, U.S.A. 3. Pollen carried on the proboscis was identified from over 700 individuals of 14 hawkmoth species attracted to lights over a 2-year period. 4. Two plant species dominated pollen loads, suggesting that hawkmoths use these species extensively as nectar sources: Datura wrightii (Solanaceae), a classic hawkmoth-pollinated plant, and Agave palmeri (Agavaceae), which is known to be used extensively by bats. Field surveys indicate that both species are relatively rare in the flowering community. Little or no pollen was present on the moths from the most common plant species in flower during the study. 5. The dominance of Agave in pollen loads suggests that this typically bat-pollinated species may be subsidising pollinator populations of the hawkmoth-pollinated flora. 6. Three groups of hawkmoths within this community are identified based on larval diets (reported in the literature) and adult diets (documented here): those that, at a given site, heavily exploit the same plant species at both life-history stages (Manduca sexta and M. quinquemaculata); those that have broad local associations at both life-history stages (Hyles lineata); and those that exhibit narrow but non-overlapping local associations at the two life-history stages (all other hawkmoths at this site).
• Riffell, J. A., Alarcón, R., Abrell, L., Davidowitz, G., Bronstein, J. L., & Hildebrand, J. G. (2008). Behavioral consequences of innate preferences and olfactory learning in hawkmoth-flower interactions. Proceedings of the National Academy of Sciences of the United States of America, 105(9), 3404-9.
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  Spatiotemporal variability in floral resources can have ecological and evolutionary consequences for both plants and the pollinators on which they depend. Seldom, however, can patterns of flower abundance and visitation in the field be linked with the behavioral mechanisms that allow floral visitors to persist when a preferred resource is scarce. To explore these mechanisms better, we examined factors controlling floral preference in the hawkmoth Manduca sexta in the semiarid grassland of Arizona. Here, hawkmoths forage primarily on flowers of the bat-adapted agave, Agave palmeri, but shift to the moth-adapted flowers of their larval host plant, Datura wrightii, when these become abundant. Both plants emit similar concentrations of floral odor, but scent composition, nectar, and flower reflectance are distinct between the two species, and A. palmeri flowers provide six times as much chemical energy as flowers of D. wrightii. Behavioral experiments with both naïve and experienced moths revealed that hawkmoths learn to feed from agave flowers through olfactory conditioning but readily switch to D. wrightii flowers, for which they are the primary pollinator, based on an innate odor preference. Behavioral flexibility and the olfactory contrast between flowers permit the hawkmoths to persist within a dynamic environment, while at the same time to function as the major pollinator of one plant species.
• Nijhout, H. F., Davidowitz, G., & Roff, D. A. (2006). A quantitative analysis of the mechanism that controls body size in Manduca sexta. Journal of Biology, 5.
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  PMID: 16879739;PMCID: PMC1781520;Abstract: Background: Body size is controlled by mechanisms that terminate growth when the individual reaches a species-specific size. In insects, it is a pulse of ecdysone at the end of larval life that causes the larva to stop feeding and growing and initiate metamorphosis. Body size is a quantitative trait, so it is important that the problem of control of body size be analyzed quantitatively. The processes that control the timing of ecdysone secretion in larvae of the moth Manduca sexta are sufficiently well understood that they can be described in a rigorous manner. Results: We develop a quantitative description of the empirical data on body size determination that accurately predicts body size for diverse genetic strains. We show that body size is fully determined by three fundamental parameters: the growth rate, the critical weight (which signals the initiation of juvenile hormone breakdown), and the interval between the critical weight and the secretion of ecdysone. All three parameters are easily measured and differ between genetic strains and environmental conditions. The mathematical description we develop can be used to explain how variables such as growth rate, nutrition, and temperature affect body size. Conclusion: Our analysis shows that there is no single locus of control of body size, but that body size is a system property that depends on interactions among the underlying determinants of the three fundamental parameters. A deeper mechanistic understanding of body size will be obtained by research aimed at uncovering the molecular mechanisms that give these three parameters their particular quantitative values. © 2006 Nijhout.
• Davidowitz, G., Roff, D. A., & Nijhout, H. F. (2005). A physiological perspective on the response of body size and development time to simultaneous directional selection. Integrative and Comparative Biology, 45(3), 525-531.
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  PMID: 21676797;Abstract: Natural selection typically acts on multiple traits simultaneously. Quantitative genetics provides the theory for predicting the response to selection of multiple traits and predicts symmetrical responses to selection (the response to upward selection on both traits is equal to their response to downward selection). In reality, however, the response to simultaneous selection on two traits is often asymmetrical. We provide a physiology-based framework to explain the asymmetrical response to simultaneous selection on two important life history traits: body size and development time. The tobacco hornworm, Manduca sexta, is particularly well suited for such a study, as the physiological control of body size and development time is well known in this species. Three physiological factors control both life history traits in M. sexta: growth rate, the critical weight that measures the timing of the onset of the cessation of juvenile hormone secretion (which initiates the processes leading to pupation) and the time interval between the critical weight and secretion of the molting hormone 20-hydroxyecdysteroid (the interval to cessation of growth, ICG). Asymmetry in the response to simultaneous selection on the two life history traits is due to the different types of selection acting on the three physiological factors. The critical weight and ICG are always under synergistic selection when both focal traits are selected in the same direction and under antagonistic selection when the focal traits are selected in opposite directions. Growth rate follows the opposite pattern. We propose a general model to explain the asymmetric response to simultaneous selection. This model emphasizes the importance of physiological processes in understanding evolutionary responses to selection and the control of complex traits.
• Davidowitz, G., & Nijhout, H. F. (2004). The physiological basis of reaction norms: The interaction among growth rate, the duration of growth and body size. Integrative and Comparative Biology, 44(6), 443-449.
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  PMID: 21676730;Abstract: The general effects of temperature and nutritional quality on growth rate and body size are well known. We know little, however, about the physiological mechanisms by which an organism translates variation in diet and temperature into reaction norms of body size or development time. We outline an endocrine-based physiological mechanism that helps explain how this translation occurs in the holometabolous insect Manduca sexta (Sphingidae). Body size and development time are controlled by three factors: (i) growth rate, (ii) the timing of the cessation of juvenile hormone secretion (measured by the critical weight) and (iii) the timing of ecdysteroid secretion leading to pupation (the interval to cessation of growth [ICG] after reaching the critical weight). Thermal reaction norms of body size and development time are a function of how these three factors interact with temperature. Body size is smaller at higher temperatures, because the higher growth rate decreases the ICG, thereby reducing the amount of mass that can accumulate. Development time is shorter at higher temperatures because the higher growth rate decreases the time required to attain the critical weight and, independently, controls the duration of the ICG. Life history evolution along altitudinal, latitudinal and seasonal gradients may occur through differential selection on growth rate and the duration of the two independently controlled determinants of the growth period.
• Davidowitz, G., D'Amico, L. J., & Nijhout, H. F. (2004). The effects of environmental variation on a mechanism that controls insect body size. Evolutionary Ecology Research, 6(1), 49-62.
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  Abstract: Adult body size in animals is determined by the duration of the growth period and the amount of mass gained during that period. Few models of body size regulation distinguish between these two components or explicitly address the mechanisms that control the duration of the growth period. Body size in the tobacco hornworm Manduca sexia is controlled by three underlying physiological factors: growth rate; timing of the onset of juvenile hormone decay (which initiates the processes leading to pupation), as measured by the critical weight; and the timing of prothoracicotropic hormone (PTTH, which stimulates ecdysteroid secretion) and ecdysteroid secretion, as measured by the interval to cessation of growth (ICG, the time interval between the attainment of the critical weight and entry into the pre-pupal wandering stage). The critical weight and the ICG determine the duration of the growth period, while growth rate determines how much mass accumulates during that period. We studied how phenotypic plasticity of body size in M. sexia, in response to variation in temperature and diet quality, is affected by phenotypic plasticity of these three physiological determinants of body size. We show that plasticity of size in response to diet quality is regulated by variation in growth rate and critical weight, while plasticity of size in response to temperature is regulated by variation in growth rate and the ICG. These results demonstrate the importance of the timing of hormonal events in the regulation of phenotypic plasticity. We suggest that the differential sensitivity of the physiological processes that regulate body size may enable insects to adjust adult body size in response to simultaneous variation in multiple types of environmental stimuli.
• Davidowitz, G., D'Amico, L. J., & Nijhout, H. F. (2003). Critical weight in the development of insect body size. Evolution & Development, 5(2), 188-97.
• Davidowitz, G., D'Amico, L. J., & Nijhout, H. F. (2003). Critical weight in the development of insect body size. Evolution and Development, 5(2), 188-197.
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  PMID: 12622736;Abstract: Body size is one of the most important life history characters of organisms, yet little is known of the physiological mechanisms that regulate either body size or variation in body size. Here, we examined one of these mechanisms, the critical weight, which is defined as the minimal mass at which further growth is not necessary for a normal time course to pupation. The critical weight occurred at 55% of peak larval mass in laboratory-reared larvae of the tobacco hornworm Manduca sexta. We examined the effects of genetic and environmental variation in the critical weight on body size. As in many other insects, Manduca larvae reared on poor diets were smaller and those reared at lower temperatures were larger than control animals. We demonstrated that the critical weight was lower on low quality diets but did not change with temperature. There was significant genetic variation for body size, for plasticity of body size, and for critical weight, but not for plasticity of critical weight. Variation in the critical weight accounted for 73% of between-family variance in peak larval size, whereas plasticity of critical weight was not significantly correlated with plasticity of body size. Our results suggest that although critical weight is an important factor in determining body size and enabling the evolution of body size, it may, at the same time, act as a constraint on the evolution of plasticity of body size. Thus, the determinants of body size and the determinants of plasticity of body size do not need to be identical.
• Davidowitz, G. (2002). Does precipitation variability increase from mesic to xeric biomes?. Global Ecology and Biogeography, 11(2), 143-154.
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  Abstract: Desert precipitation is often characterized as more variable than precipitation in nondesert biomes. However, empirical support for this generalization is lacking. I analysed precipitation variability in five desert and four nondesert biomes that represent a xeric to mesic gradient in the South-western United States, using data from 328 weather stations, for a total of 18 337 station-years. I examined precipitation variability at two temporal scales: among years and among months, within years. Each of these scales was analysed for annual precipitation, summer precipitation and winter precipitation for a total of 18 separate analyses. Overall, precipitation variability does increase as precipitation decreases. However, I found little support for the generalization that desert precipitation is more variable than precipitation in nondeserts. At most time scales, many south-western American desert biomes are no more variable than nondesert biomes. The level of variability is highly dependent on which desert biome is under study, where in the biome a particular site is located, and what time scale is used to measure variability. Certain desert sites are in fact more variable than nondesert sites, in some cases by as much as fivefold. However, and perhaps more importantly, each desert biome includes many sites that are no more variable, across many or all time scales, than sites in the grassland or pine forest biomes. These results emphasize the importance of measuring variability for each study site of interest and caution against extrapolating from a few sites to biomes or gradients in general. Implications for the study of adaptations to environmental variability are discussed.
• D'Amico, L., Davidowitz, G., & Nijhout, H. F. (2001). The developmental and physiological basis of body size evolution in an insect. Proceedings of the Royal Society B: Biological Sciences, 268(1476), 1589-1593.
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  PMID: 11487406;PMCID: PMC1088782;Abstract: The evolution of body size is a dominant feature of animal evolution. However, little is known about how the underlying developmental mechanisms that determine size change as body size evolves. Here we report on a case of body size evolution in the tobacco hornworm Manduca sexta that occurred over a period of nearly 30 years. We take advantage of an extensive series of physiological studies performed in the early 1970s that established the parameters that regulate body size in this species and compare their values with those of modern individuals that are descendants of the same colony. We show that three of the five processes that determine adult body size changed during this period, while two remained constant. Changes in these three developmental processes completely account for the observed evolutionary change in body size.
• Rosenzweig, M. L., & Davidowitz, G. (1998). The latitudinal gradient of species diversity among North American grasshoppers (Acrididae) within a single habitat: a test of the spatial heterogeneity hypothesis. Journal of Biogeography, 25(3), 553-560. doi:10.1046/j.1365-2699.1998.2530553.x
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  The spatial heterogeneity hypothesis predicts a positive relationship between habitat complexity and species diversity: the greater the heterogeneity of a habitat, the greater the number of species in that habitat. On a regional scale, this hypothesis has been proposed to explain the increase in species diversity from the poles to the tropics: the tropics are more diverse because they contain more habitats. On the local scale, the spatial heterogeneity hypothesis suggests that the tropics are more diverse because they contain more microhabitats. The positive relationship between habitat heterogeneity and species diversity, on the local scale, is well documented. In this paper, we test whether habitat heterogeneity on the local scale can explain the latitudinal gradient of species diversity on the regional scale. We determined the latitudinal gradient of species diversity of 305 species of North American grasshoppers using published

Presentations

• Britton, S., & Davidowitz, G. (2021, November). Increased thermal response does not lead to life history effects indicating a cost to melanization. Entomological Society of America. Denver, CO.
• Busby, K., Davidowitz, G., & Bronstein, J. (2021, January). Will carpenter bee (Xylocopa californica) nest temperatures exceed larval CTmax?. Society for integrative and Comparative Biology (SICB). Washington, DC virtual.
• Cruz, A., Davidowitz, G., Hunter, M. S., & Bronstein, J. (2021). Scaling up: Linking thermal ecology to species interactions in a sessile herbivore. Ecological Society of America. virtual.
• Davidowitz, G. (2021). Overview of the edible insect program at the UA: what we are doing and where do we want to go. Entomology Departmental Seminar.
• Davidowitz, G. (2021, April). Insect protein for food and feed. USAID-USDA seminar. virtual: USDA-USAID.
• Busby, K., Davidowitz, G., & Bronstein, J. (2020, Jan). Thermolimit Respirometry Determines Relative CTmax Among Carpenter Bee Life Stages. Society for Integrative and Comparative Biology (SICB). Austin, TX: Entomological Society of America.
• Davidowitz, G. (2019, Apr). Using insects to address the 9 billion problem. Food Fungi and the ForestFood Fungi and the Forest.
• Davidowitz, G. (2019, Apr). Using insects to address the 9 billion problem. Whetstone Unit, Arizona Department of CorrectionsWhetstone Unit, Arizona Department of Corrections.
• Davidowitz, G. (2019, Jan). Using insects to address the 9 billion problem. Wedges Against Hunger. UC Riverside.
• Davidowitz, G. (2019, July). What do pollinators do with the nectar they drink?. Changchun, China. Changchun, China: Northeast Normal University.
• Davidowitz, G. (2019, May). Using insects to address the 9 billion problem. Herbarium Lunch. UA Herbarium: Herbarium.
• Davidowitz, G. (2019, Oct). Edible Insects: the food of the future is here now. UA Insect Festival. UA: Insect Festival.
• Davidowitz, G. (2019, Oct). Insects as Food and Feed. University, Industry Consortium (UIC). Saint Louis, MO: University, Industry Consortium (.
• Davidowitz, G. (2019, Oct). What do pollinators do with the nectar they drink?. EEB Departmental SeminarUA Department of Ecology and Evolutionary Biology.
• Davidowitz, G. (2019, Sep). Entomophagy, the science of eating insects. Food and Drug Administration, Pacific Retail Food Safety Seminar. Mesa, AZ: Food and Drug Administration.
• Davidowitz, G., Ziv, Y., Kozhoridze, G., & Tigreros, N. (2019, Nov). Effects of habitat fragmentation on the physiology of a terrestrial beetle. Entomological Society of America (ESA). St Louis, MO: Entomological Society of America (ESA).
• Busby, K., Prudic, K. L., Davidowitz, G., & Bronstein, J. (2018, June). Forecasting the developmental niche of Xylocopa californica in a changing thermal world. Entomological Society of America, Pacific Branch. Reno, NV: ESA.
• Davidowitz, G. (2018, August). What do pollinators do with the nectar they drink?. Entomology Seminar SeriesEntomology Seminar Series.
• Davidowitz, G. (2018, January). Nectarivores Use Sugar to Reduce Oxidative Damage From Flight. Society for Integrative and Comparative Biology (SICB).
• Davidowitz, G. (2018, July). What do pollinators do with the nectar that they drink?. University of Campinas, Brazil, Institute of Biology. Campinas Brazil: University of Campinas.
• Davidowitz, G. (2018, July). What do pollinators do with the nectar that they drink?. University of Sao Paulo, Brazil. University of Sao Paulo, Brazil, Department of Ecology: University of Sao Paulo, Brazil.
• Davidowitz, G. (2018, November). From concept to practice: teaching how concepts in insect physiology work in the real world. Symposium on Teaching Insect Physiology in a Changing World: Crossing Borders Between Traditional and Integrative Pedagogy, Entomological Society of America, Vancouver, Canada. Vancouver, Canada: Entomological Society of America.
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  Invited Symposium
• Davidowitz, G. (2018, November). Using insects to address the 9 billion problem. AG100. INTEL, Phoenix: CALS.
• Davidowitz, G. (2018, October). Edible insects: the food of the future. Controlled Environment Agriculture Center. UA, CEAC.
• Davidowitz, G. (2018, October). Exhibitor ATC Arizona Technology Council. Southern Arizona Tech Business Expo. Tucson Convention Center: Arizona Technology Council.
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  Exhibitor of edible insects
• Davidowitz, G. (2018, October). HexaFeast: The edible insect program at the University of Arizona. EIS lunchEIS.
• Smith, G., Davidowitz, G., Alarcon, R., Papaj, D. R., & Bronstein, J. (2018, January). Intraspecific variation in nectar use by foraging hawkmoth. American Society of Naturalists. Asilomar, CA: American Society of Naturalists.
• Wilson, J. K., Ruiz, L., & Davidowitz, G. (2018, November). Within-host tachinid parasitoid density affects parasitoid body size and allometry. Entomological Society of America. Vancouver, Canada.
• Davidowitz, G. (2017, July). Moth body-building: within-individual resource allocation strategies used to build a moth. Kellogg Biological Station (KBS). Kellogg Biological Station (KBS).
• Davidowitz, G. (2017, July). Moth body-building: within-individual resource allocation strategies used to build a moth. UBRP. UA.
• Davidowitz, G. (2017, March). How one size fits all doesn't fit anyone. Symposium in Honor of Professor Michael Rosenzweig. UA.
• Davidowitz, G. (2017, November). The other Arizona beef: using insects to address the 9 billion problem. Frontiers in Life Sciences CALS. UA Campus: CALS.
• Davidowitz, G. (2017, October). Insects as an alternate source of protein for human consumption. Insect Festival. UA.
• Davidowitz, G. (2017, October). Moth body-building and resource use with larval meanderings through CEAC. Covering Environments—The CEAC Monthly Seminars. UA.
• Davidowitz, G., McCue, M., & Levin, E. (2017, January). More than just sugar: allocation of nectar amino acids and fatty acids in a Lepidopteran. Society for Integrative and Comparative Biology. New Orleans: SICB.
• Davidowitz, G., McCue, M., & Levin, E. (2017, October). Beyond sugar: allocation and metabolism of nectar amino acids and fatty acids in a Lepidopteran. Entomological Society of America. Denver.
• Davidowitz, G. (2016, January). Symposium on Evolutionary Endocrinology: Hormones as mediators of evolutionary phenomena. Society for Integrative and Comparative Biology. Portland, OR: Society for Integrative and Comparative Biology.
• Davidowitz, G. (2016, January). Within-individual resource allocation strategies are affected by sex, body part, and quality of resources. American Society of Naturalists. Asilomar, CA: American Society of Naturalists.
• Davidowitz, G. (2016, May). Moth body-building: within-individual resource allocationstrategies used to build a moth. Invited Seminar. Neufchatel, Switzerland: Universite’ de Neuchatel, Switzerland.
• Davidowitz, G. (2016, May). Moth body-building: within-individual resource allocationstrategies used to build a moth. Invited Seminar. Zurich, Switzerland: University of Zurich-Irchel, Switzerland.
• Davidowitz, G. (2016, May). Within-individual resource allocationstrategies used to build a moth. Invited Seminar. Paris, France: Université Pierre-et-Marie-Curie (UPMC - Paris VI).
• Simmons, G., Hood-Nowotny, R., Davidowitz, G., Costa, H., Munoz, B., & Greene, T. (2016, April). Development of stable Isotopes and new biochemical tools for identification of sterile insects and Determination of pest origin. Ecological Society of America- Pacific Branch. Honolulu, HI: Ecological Society of America.
• Davidowitz, G. (2015, December). Insects that kill!. Arizona Mystery Writers. Tucson,Az: Arizona Mystery Writers.
• Davidowitz, G. (2015, January). Moth body-building: within-individual resource allocationstrategies used to build a moth. Ecology and Evolutionary Biology Seminar. EEB: EEB.
• Davidowitz, G. (2015, May). Moth body-building: within-individual resource allocationstrategies used to build a moth. Ecology and Evolution of Species Interactions. Paris: Ecole Normal Superior.
• Davidowitz, G. (2015, October). Moth body-building: within-individual resource allocationstrategies used to build a moth. Cornell University, Department of Entomology Seminar. Cornell University: Department of Entomology.
• Davidowitz, G. (2015, September). Moth body-building: within-individual resource allocationstrategies used to build a moth. Entomology Seminar. Department of Entomology: Entomology.
• Davidowitz, G., Favela, A., Allen, N., Gronenberg, W., & Moore, A. F. (2015, January). Male and female allocation strategies to head function is mediated by resource limitation. Society for Integrative and Comparative Biology (SICB). West Palm Beach, Florida: SICB.
• Levin, E., & Davidowitz, G. (2015, January). Does male feeding affects female fecundity?. Society for Integrative and Comparative Biology. West Palm Beach Florida: SICB.
• Wone, B., Ojha, J., & Davidowitz, G. (2015, APR). Animal models of human muscle aging and disease: the hawk moth, Manduca sexta, flies forward. FASEB JOURNAL.
• Davidowitz, G. (2014, Apr). How do we integrate sub-organismal with supra-organismal processes?. Entomological Society of America- Pacific Branch.
• Davidowitz, G. (2014, May). How do insects prioritize energy and resource allocation?. Research Innovation Challenge.
• Davidowitz, G. (2014, Nov). How to build a moth with limited resources?. Department of Biology, North Dakota State University.
• Davidowitz, G. (2014, Oct). Physiological synergism and antagonism in the evolution of life histories. American Physiological Society.
• Davidowitz, G. -. (2014, Spring). Energy allocation among body parts within an individual. SICB. Austin, TX.
• Davidowitz, G., Daws, A., Moore, A., Helm, B., & Stillwell, C. (2014, Jan). Energy allocation among body parts within an individual.. Society for Integrative and Comparative Biology.
• Davidowitz, G., Roff, D., & Nijhout, F. (2014, Jun). Physiological synergism and antagonism determine the evolution of life histories: A Critical Point Framework. Society for the Study of Evolution.
• Papaj, D. R., Davidowitz, G., & Mitra, C. (2014, August). Passing the salt: Nuptial gifts in a swallowtail butterfly. International Society for Behavioral Ecology (ISBE).
• Wone, B., Ojha, J., & Davidowitz, G. (2014, Oct). Age Related Changes in Flight Muscle Ultra- structures of the Hawk moth, Manduca sexta: A novel Non-vertebrate Animal Model for Investigating Vertebrate Skeletal Muscle Function, Disease, Degeneration, and Aging. American Physiological Society.
• Davidowitz, G. -. (2012). Allocation tradeoffs and relative humidity in the life of Manduca sexta. Tucson, AZ: Invited by Hildebrand lab group.
• Davidowitz, G. -. (2012). Conversations with Faculty. Undergraduate Biology Research Program (UBRP) orientation. Tucson, AZ.
• Davidowitz, G. -. (2012). Does relative humidity affect foraging decisions in desert hawkmoths. Hexapodia (CIS). Tucson, AZ.
• Davidowitz, G. -. (2012). Forensic Entomology. Invited talk. Tucson, AZ: Mystery Writers of Southern Arizona.
• Davidowitz, G. -. (2012). It's a dry heat for insects too! How do hawk moths survive the desert of southern ArizonaInvited by Friends of Florida Canyon at the Santa Rita Experimental Range.
• Davidowitz, G. -. (2012). Physiological antagonism and synergism in the evolution of insect body size. Symposium on insect morphometrics. Knoxville, TN: Entomological Society of America.
• Davidowitz, G. -. (2012). Relative humidity affects foraging decisions in desert hawkmoths. Invited speaker: Israel Entomology Society. Rehovot, Israel: Israel Entomology Society.
• Davidowitz, G. -. (2012, January). Contributed:Do resource thresholds play a role in the onset of maturation--a key life history transition?. SICB meeting. Charleston, SC.
• Davidowitz, G. -. (2011). Davidowitz Lab Research. UBRP Conversations with Faculty. Tucson, AZ.
• Davidowitz, G. -. (2011). Nectar type, relative humidity and the flight-fecundity tradeoff in a semi arid environment. Research Insights in Semiarid Ecosystems (RISE)Symposium. Tucson, AZ.
• Davidowitz, G. -. (2011). Physiological antagonism and synergism in the evolution of life histories. Invited seminar for Joint Faculty Position. Tucson, AZ.
• Davidowitz, G. -. (2011). The NSF review process: the inside scoop. PERT seminar on NSF funding. Tucson, AZ.
• Davidowitz, G. -. (2011, January). The importance of nectar sugar content in Manduca sexta flight performance and cost. 2011 SICB meeting. Salt Lake city.
• Davidowitz, G. -. (2011, January). Tracheal Growth and Plasticity in 5th Instar Manduca sexta. 2011 SICB meeting. Salt Lake City.

Poster Presentations

• Kozhoridze, G., Tigreros, N., Davidowitz, G., Barki, G., & Ziv, Y. (2019, Dec). Interactions between scale-dependency and an agricultural matrix determine the response of a tenebrionid beetle to habitat fragmentation. British Ecological Society. Belfast, Ireland: British Ecological Society.
• Slagle, M., & Davidowitz, G. (2019, Nov). Grubs for Dinner: Cotinis mutabilis grubs can be a sustainable and economic protein source. Entomological Society of AmericaEntomological Society of America.
• Davidowitz, G., McCue, M., & Levin, E. (2017, April). Sex differences in the utilization of essential and non-essential amino acids in a Lepidoptera. Experimental Biology. Chicago: FASEB.
• Levin, E., McCue, M., & Davidowitz, G. (2017, October). Sex differences in the utilization of essential and non-essential amino acids in a Lepidoptera. Entomological Society of America. Denver.
• Simmons, G., Hood-Nowotny, R., Davidowitz, G., Costa, H., Munoz, B., & Greene, T. (2016, January). Development of Stable Isotopes and new Biochemical Tools for Identification of Sterile Insects and Determination of Pest Origin. Orchard Pest and Disease Management Conference. Portland, OR.
• Arcas, S., Davidowitz, G., & Contreras, H. L. (2014, Jun). Feeding on the wing: energy allocation and prioritization in the hawk moth Manduca sexta. Society for Experimental Biology.
• Davidowitz, G. (2014, Oct). Sex and Nutrient Effects on Energy Allocation Among Body Parts Within an Individual. American Physiological Society.
• Davidowitz, G., Moore, A. F., Daws, A., & Stillwell, C. (2014, Jun). Nutrient effects on energy allocation among body parts within an individual. Society for the Study of Evolution.
• Wone, B., Ojha, J., Contreras, H., & Davidowitz, G. (2014, Jun). More is not always better: a hidden cost of the flightfecundity trade-off in the hawk moth, Manduca sexta. Experimental Biology.
• von Arx, M., Moore, A. F., Davidowitz, G., & Arnold, A. E. (2014, Aug). Diversity and distribution of microbial communities in floral nectar in two typical plants of the Sonoran Desert. International Symposium on Insect-Plant Relationships, Neuchatel, Switzerland.
• Mitra, C., Davidowitz, G., & Papaj, D. R. (2013, July). Puddling behavior in butterflies: effects on male mating success. Animal Behavior Society National Meeting. University of Colorado: Animal Behavior Society.
• Davidowitz, G. -. (2012, January). Environmental Humidity Effects on M. Sexta Foraging Behavior. SICB meeting. Charleston, SC: SICB.
• Davidowitz, G. -. (2012, January). The Effects of Food Availability on the Workforce of a Social Insect: Response of Worker Production in Bumble Bee (Bombus impatiens) Colonies When Food Availability is Manipulated. SICB meeting. Charleston, SC: SICB.

Others

• Davidowitz, G. (2019, Dec). Capstone Students Get Agile. Senior Design News, College of Engineering.
• Davidowitz, G., & Dieckman, E. (2019, Apr). Grab that Grasshopper. UA News.
• Davidowitz, G. (2018, August). Engineering design program opens biggest year yet. College of Engineering- Engineering Design Program. http://engineeringclinic.arizona.edu/engineering-design-program-biggest-year-yet-open-house
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  UA media of edible insect project
• Davidowitz, G. (2018, March). Grant-writing panel. Graduate Student Survival Skills and Ethics class, SLHS649.
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  Panel on grant writing for graduate student survival skills course
• Davidowitz, G. (2018, November). Arizona Daily Star. Grad students goal: Remove bugaboo about eating insects. Arizona Daily Star. https://tucson-com.cdn.ampproject.org/v/s/tucson.com/news/local/eat-local-ua-graduate-student-raising-bugs-at-home-and/article_ffe01afb-7d68-53c1-84ce-13926ee01e58.amp.html?amp_js_v=a2&amp_gsa=1&usqp=mq331AQCCAE%3D#referrer=https%3A%2F%2Fwww.google.com&amp_tf=From%20%251%24s&ampshare=https%3A%2F%2Ftucson.com%2Fnews%2Flocal%2Feat-local-ua-graduate-student-raising-bugs-at-home-and%2Farticle_ffe01afb-7d68-53c1-84ce-13926ee01e58.html
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  Media article about edible insect project. AZ DAily Star
• Davidowitz, G. (2018, November). Bugs for Breakfast. Modern Growing: Maximum Yield. https://view.joomag.com/maximum-yield-usa-february-2018/0044660001516402810
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  Maximum Yield media about edible insect program
• Davidowitz, G. (2018, November). Fund Your Sustainability Project With a Grant From the Green Fund. UA@Work. https://uaatwork.arizona.edu/lqp/fund-your-sustainability-project-grant-green-fund
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  Media article of green fund grant on edible insects
• Davidowitz, G. (2018, October). PBS NOVA. These Butt-Blasting Beetles Love to Cuddle. PBS NOVA. https://www.pbs.org/wgbh/nova/article/bombardier-beetle-cluster
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  PBS NOVA media article of Schaller et al. 2018
• Davidowitz, G., & Bronstein, J. (2018, July). One week course in plant-animal interactions. University of Campinas, Brazil.
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  This was a one week field course in plant-animal interactions with over 20 PhD students from Brazil