BEHAVIORAL-CHANGES IN TRIBOLIUM BEETLES INFECTED WITH A TAPEWORM - VARIATION IN EFFECTS BETWEEN BEETLE SPECIES AND AMONG GENETIC STRAINS

We report behavioral alterations induced by tapeworm (Hymenolepis dimi nuta) infection in several genetic strains of two species of flour bee tles, Tribolium, under two infection levels in a laboratory environmen t. Under a high level of infection, Tribolium castaneum (strain cSM) s hows decreased emigration and surface-seeking behavior and increased c annibalism. In contrast Tribolium confusum (strain b+) shows increased emigration and surface-seeking behavior, and cannibalism is not signi ficantly changed. Under a low level of infection, emigration is not af fected in any of the 11 genetic strains examined. Prevalence of parasi tism is positively associated with emigration rate. Different genetic strains of T. confusum exhibited different susceptibility to tapeworm infection, suggesting intraspecific genetic variation in susceptibilit y to infection. This genetic basis may reflect past differences in sel ection resulting from different infection histories and suggests susce ptibility to infection could evolve as a result of future selection. T his variation in changes in host behavior seen among genetic strains a lso suggests that caution is needed before generalizing about expected changes in host behavior induced by a particular parasite and before concluding that such charges represent an adaptive manipulation of hos t behavior by a parasite species.