INFLUENCE OF TAPEWORM INFECTION ON THE PRODUCTION OF AGGREGATION PHEROMONE AND DEFENSIVE COMPOUNDS IN TRIBOLIUM-CASTANEUM

Recent studies suggest that parasites affect host development, reprodu ction, and behavior through alterations of host hormones and pheromone s, or other hormone-triggered biochemical events. We previously report ed that Hymenolepis diminuta infection affects surface-seeking and can nibalism behaviors, and reduces male sperm precedence of Tribolium cas taneum beetles. This study examined the quantitative effects of H. dim inuta on the production of aggregation pheromone and 3 defensive compo unds in male T. castaneum beetles, using 2 wild-caught, geographically distinct T. castaneum strains; For the c-Madison strain, infected bee tles exhibited a 2- to 22-fold increase in defensive compounds; conver sely, no changes were observed in strain c-Africa. Parasite infection did not significantly influence aggregation pheromone secretion in eit her strain. Because defensive compounds function as repellents or dete rrents to other insects, parasite-induced increases in the secretion o f defensive compounds may be a physiologic clue for the behavioral cha nges in infected T. castaneum beetles. Significant among-strain variat ion in defensive compound production seen in infected beetles suggests that caution is needed before generalizing about changes in volatile production and in host behavior induced by a parasite.