TASTING GREEN LEAF VOLATILES BY LARVAE AND ADULTS OF COLORADO POTATO BEETLE, LEPTINOTARSA-DECEMLINEATA

Larvae and adults of the Colorado potato beetle, Leptinotarsa decemlin eata (Say), are shown to have galeal gustatory cells that are highly s ensitive to distillate of potato leaf extracts, (E)-2-hexen-1-ol, (E)- 2-hexenal, and other saturated and unsaturated six-carbon alcohols. In larvae and adults, the sensory response patterns elicited by leaf hom ogenate, leaf distillate and a mixture of these two extracts differ in subtle ways. Beetle larvae feed most readily on Millipore disks treat ed with leaf homogenate and the mixture, but they did not feed on disk s treated with leaf distillate. The differences in behavioral response and sensory input are used to derive a potential gustatory code that may stimulate different levels of feeding. This code may be disrupted by compounds present in nonhost leaves, thus leading to reduced feedin g. Possible interactions of sapid leaf volatiles, amino acids, sugars, and potentially deterrent plant compounds are discussed.