Effect of the insect feeding deterrent 1-allyloxy-4-propoxybenzene on olfactory responses and host choice of Varroa destructor

The ectoparasitic mite, Varroa destructor Anderson and Trueman (Acar: Varroidae), is a major threat for the honey bee, Apis mellifera L. Varroa behavior and physiology are influenced by compounds produced by the honey bee, as well as cues from the general colony environment. As part of our effort to disrupt varroa host chemosensing, we tested 1-allyloxy-4-propoxybenzene, 3c { 3,6 }, a known feeding deterrent of Lepidoptera larvae and a repellent of mosquitoes of similar activity to DEET. Its effect on varroa mites was evaluated by electrophysiological and behavioral bioassays. Its effect on honey bee chemosensing was also assessed. Compound 3c{ 3,6 } is sensed by honey bees, but the detection of the compound alone by varroa is not clear. The electrophysiological study showed that 3c{ 3,6 } decreases the varroa foreleg responses towards head space odor of nurse bees. However, the response of honey bee antennae towards nurse bee head space odor was not affected. Consistent with electrophysiological studies, in the presence of 3c{ 3,6 } , the ability of varroa to reach any host decreased at the end of the experiment. No lethal effect to the honey bees was recorded. These data showed that 3c{ 3,6 } affects the peripheral olfactory system of varroa by disrupting the chemical recognition process.