Palatability and Toxicity of the Colorado Potato Beetle (Coleoptera: Chrysomelidae) to Domestic Chickens

Abstract

Both larval and adult Colorado potato beetles, Leptinotarsa decemlineata (Say), were distasteful to young domestic chickens when offered alternately with palatable mealworms. All chicks in trials using Colorado potato beetle larvae pecked at the first larva offered, whereas only 70% pecked at the second and 47% at the third, suggesting aversive learning based on distastefulness. Mealworms coated with homogenized Colorado potato beetle larvae were not rejected. Chicks force-fed freshly homogenized Colorado potato beetle larvae gained less weight than controls, although the difference was significant only at a medium dose (three larvae per chick per day). Chicks offered adult beetles continued to peck at most of them during the course of a single trial, but the same chicks pecked at fewer in two subsequent trials, which again suggests aversive learning based on distastefulness. Adult beetles without elytra were three times as likely as intact beetles to be eaten by naive chicks, and thus the elytra are probably the source of much of the unpalatability of adult beetles. The elytra also provide important mechanical protection for the beetles: more than half the pecked (but not eaten) beetles without elytra died, but only one-fourth of the pecked intact beetles died. No larvae that were pecked but not eaten survived.