Meeting Abstract

76.5  Wednesday, Jan. 6  Nutritional effects on migration and immunity: Mormon crickets in Nevada contrast sharply with a band in Utah SRYGLEY, R.B.**; LORCH, P.D.; USDA-Agricultural Research Service; Kent State University, Ohio robert.srygley@ars.usda.gov

Mormon crickets (Anabrus simplex) form large migratory bands that march over rangeland in the western U.S. in search of nutrients. Immune defense is particularly relevant to survival in migratory bands, but little is known about the role of nutrition in insect immunity. We hypothesized that immune defenses are compromised in Mormon cricket bands due to nutrient limitations. To determine general constituents lacking in their diet, we presented captive members of the band with both protein rich and carbohydrate rich diets. Members of a migratory band in Utah preferred the protein diet, indicating a protein deficiency, whereas members of the Nevada band preferred the carbohydrate diet and showed little interest in proteins. These two kinds of nutrient deficiency were associated with different kinds of immunodeficiency. In the protein-deficient band, a protein diet enhanced phenoloxidase (PO) activity, an enzyme involved in wound healing and fighting foreign invasion. PO activity was unaffected by the dietary treatments in the carbohydrate-deficient band. In the carbohydrate-deficient band, feeding on carbohydrates enhanced the crickets’ ability to encapsulate foreign particles and lyse bacteria, whereas these abilities were unaffected by the dietary treatments in the protein-deficient band. The difference in components of the immune system that are enhanced by the contrasting dietary constituents suggests that PO activity requires protein whereas encapsulation and antibacterial activity require carbohydrate. Thus there may not be a common currency for the generalized immunity of insects. In the general framework of ecological nutrition, insects may require a balanced diet to maximize defense against invasion.