Trail following and recruitment: Response of eastern tent caterpillarMalacosoma americanum to 5β-cholestane-3,24-dione and 5β-cholestan-3-one.

Studies were conducted to determine the relative effectiveness of 5β-cholestane-3,24-dione (diketone) and 5β-cholestan-3-one (monoketone) in eliciting trail following from eastern tent caterpillars,Malacosoma americanum. In Y maze tests, trails prepared from the monoketone were followed preferentially over diketone trails, even when the diketone trail was several orders of magnitude stronger. Under field conditions, colonies readily abandoned well-developed trail systems in favor of artificial trails that were established with the monoketone. Other tests in which the caterpillars selected trails prepared from the monoketone (but not the diketone) more often than their own recruitment trails indicate that the monoketone constitutes the chemical basis of recruitment communication in this insect. The study also shows that tent caterpillars are highly sensitive to small differences in the amount of monoketone in a trail and can distinguish between new and aged trails prepared from the compound.