Meeting Abstract

44.1  Saturday, Jan. 5  Dietary effects on enzymatic immunity of migrating Mormon crickets SRYGLEY, R.B.*; USDA-Agricultural Research Service

Migration is often associated with movement away from scarce nutrients or other resources, and yet migration itself is energetically demanding. Migrating Mormon crickets lack nutrients, and supplementation of deficient nutrients slows migratory movements and enhances specific aspects of their immune systems. Migrants deficient in proteins have less spontaneous phenoloxidase (PO) activity, whereas those deficient in carbohydrates have less anti-bacterial activity. To investigate the relationship between diet, movement, and immunity further, we removed Mormon crickets from a migratory band and offered each cricket one of five diet treatments: high protein, high carbohydrate, equal weight proteins and carbohydrates (P+C), vitamins only, or water only for one hour. We then attached a radio, returned each to the migratory band, and recaptured them 18-24h later. Crickets fed protein moved furthest, those without diet or only vitamins moved less, and those fed carbohydrates or P+C moved the least. Standard intake trials also indicated that the Mormon crickets were deficient in carbohydrates. Consistent with a previous study, anti-bacterial activity was greatest in those fed carbohydrates, and there was no difference between those fed water, protein, or P+C. Total PO activity also differed between treatments and was greatest in those fed protein and least in those fed water or vitamins only. In a second experiment, we fed crickets from the same migratory band a diet treatment for 1 h and then held them in captivity until blood was drawn 4-24 h later. Dietary effects on total PO activity were not different between captive and migrating crickets, but to have a dietary effect on anti-bacterial activity the crickets had to be migrating freely. Thus a direct compromise between migratory and anti-bacterial activities is evident, whereas PO is compromised by poor protein nutrition independent of migratory activities.