BRC-BIO: How temperature-nutrient interactions affect the physiology and ecology of an insect herbivore

About This Grant

Insect herbivores make up over a quarter of the world’s biodiversity and consume up to 18% of global crops each year. These important insects face rapidly changing environmental conditions, including rising air temperatures and declining plant nutrients. Research shows that temperature and nutrition interact in complex ways: an insect’s body temperature can influence its dietary needs, and its nutritional status can influence how it responds to temperature. However, current models do not capture these interactions, limiting our ability to predict future impacts on biodiversity and agriculture. This project will investigate how temperature and nutrition jointly affect the most damaging rangeland pest in the United States, the migratory grasshopper (Melanoplus sanguinipes), which annually consumes up to 20% of the country’s available rangeland forage, causing annual estimated losses of $393 million. By combining fieldwork, laboratory experiments, and computer simulations, the research will improve ecological forecasts and inform pest management strategies that support national food security. The project will also strengthen the STEM workforce by creating paid research positions and research-based courses for a student body that is 50% first-generation-to-college. Publishing open-access educational materials and collaborating with the U.S. Department of Agriculture will further strengthen national capacity for teaching and research while building connections between public universities and federal agencies. This project will test competing hypotheses for how temperature and nutrition jointly shape organismal biology. First, mechanistic models will simulate the feeding, thermoregulation, and performance of grasshoppers across historical (1964-1994) and contemporary (1994-2024) climates. Simulations will initially assume unlimited nutrient availability and will then explore how varying nutrient availability affects model predictions. Second, common garden experiments in artificial laboratory environments will measure how interactions among body temperature, macronutrient concentrations, and macronutrient ratios affect feeding behavior and physiological performance of grasshoppers. Finally, common garden experiments in semi-natural enclosures will assess how organismal responses in the lab translate to the field. The modeling framework will generate testable predictions based on three interactive hypotheses: 1) a single-currency model in which temperature interacts with dietary energy content; 2) a limiting-nutrient model in which temperature interacts with the diet’s amount of a single limiting nutrient; and 3) a multi-currency model in which temperature interacts with the diet’s balance of multiple nutrients. By comparing model predictions with empirical data from the field and lab, this research will evaluate which hypothesis best predicts foraging and performance in temperature-nutrient environments. Together, this integrative approach will advance general theory on how organisms forage in multidimensional environments and how those foraging decisions scale up to affect physiology and ecology. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.