CAREER: Deciphering how dynamic environments and nutrition affect life history tradeoffs in a highly migratory insect pest

CAREER: Deciphering how dynamic environments and nutrition affect life history tradeoffs in a highly migratory insect pest CAREER: Deciphering how dynamic environments and nutrition affect life history tradeoffs in a highly migratory insect pest Locusts are grasshoppers that can form massive migrating swarms and devastate food security. This landscape-level pattern is regulated at the level of the individual through a phenotypic plasticity termed locust phase polyphenism. Locusts can transform between a cryptic solitarious phase that avoids other locusts and a swarming gregarious phase that aggregates and subsequently undergoes collective, long distance, and physiologically challenging migration. However, despite the impact of locusts on ecosystems and people, little is known about how environmental factors, such as nutrition and historical habitat variability, modulate the threshold at which locusts respond to density to undergo phase change. Unlike most flighted vertebrates, many insects are plastic in their capacity to develop flight apparatus and migrate. This trait makes them an excellent group for studying physiological plasticity and tradeoffs. Migratory plasticity enables organisms to prioritize migration under certain environmental contexts to access distant resources, but suppresses development of migratory characteristics in other contexts to prioritize other traits such as immune function and reproduction. In recent decades, research, largely using the Geometric Framework for Nutrition and Ecological Stoichiometry, has demonstrated that the relative availability of various nutrients strongly affects growth, reproduction, and immunology of a diversity of animals. Therefore, nutritional variation is expected to be a key factor affecting these tradeoffs, yet no prior research has looked at how nutritional variation affects the migratory potential of insects and the tradeoffs among migration, immunity, and reproduction. A combination of the PIs long-term research partnerships in Australia, established Australian plague locust lab colony and locust rearing facilities at ASU, and education plan engaging university trainees, farmers, and international scholars allow for unprecedented integrated lab and field research-connecting biological function at the level of the individual with continental-level landscapes. Intellectual merit. In the face of rapid environmental change, organisms and populations can acclimate, evolve, perish, or move. Migrating to a new habitat is a key mechanism by which many animals cope with environmental change, and how and whether animals migrate in response to alteration in climate will determine the evolutionary success of many species. The timing and magnitude of migration is highly plastic in most animals, yet we understand little about the trade-offs and mechanisms that determine whether migration occurs. Locusts are one of the best-studied systems for understanding the control of migration due to their huge agro-economic importance, and this CAREER project will take advantage of this system to answer several fundamental questions about the mechanisms that determine whether migration occurs. (1) What are the physiological trade-offs associated with migrating vs. not migrating, specifically among capacities to migrate, fight disease, and reproduce? (2) How do population density and nutritional quality (specifically protein:carbohydrate ratio of the diet) affect these tradeoffs? (3) How does historical environmental variability in the environment affect population-level variation in responses to migration-inducing stimuli? (Are populations that have evolved with more variable habitats more likely to migrate?) Answering these questions will broadly advance our understanding of why and how animals migrate, improve our ability to predict migratory responses to global change, and provide fundamental insights into the ecophysiology of one of the most economically important insect pests. Broader impacts. This CAREER project will build an integrated research, teaching, and global engagement program. This project will support a post-doc full-time and a graduate and undergraduate student part-time. In addition, the PI and her team will develop a research-intensive undergraduate course with an anticipated 75 students to engage in novel research and have opportunity to co-author peer-reviewed papers from this project. To meet the need to train more biologists and pest management officials in locust biology, particularly from underrepresented groups, this project will support a 10-day workshop at ASU. Moreover, the results will inform locust management through government partnerships and farmer field days to improve livelihoods, and human and environmental health. CAREER: Research Experiences for Undergraduates (REU) Supplement For this REU, two undergraduate students will work under the guidance of PI Arianne Cease and Postdoctoral Researcher Dr. Stav Talal on a lab based research project to study the effect of nutrition on reproductive performance in locusts. Specifically, we will evaluate how female locusts dietary macronutrient ingestion affects reproductive success, including egg physiology and hatchling performance, which expands on the originally-proposed experiments. With the support of the new REU supplement, the undergraduates will learn new wet lab techniques such as measurement of different metabolic fuels in locust adults, during different embryonic development stages and in new hatchlings. In addition, the students will learn respirometry techniques where they will measure metabolic rates and the nature of different metabolic fuel oxidation during embryo development. These experiments will all advance one of the primary research questions of the parent CAREER grant, How does nutritional quality affect life history tradeoffs?