Jacob Corcoran* and Walt Mahaffee
*USDA – Agricultural Research Service, Biological Control of Insects Research Laboratory, 1503 S. Providence Rd, Columbia, MO, 65203 (jacob.corcoran@usda.gov)

Insects rely on detection of volatile chemical cues present in the environment to find mates and the plants they feed on. As such, insects possess an extremely sensitive chemical processing system in their antennae comprised of several types of olfactory proteins. These proteins have evolved independently in insects and are not related to those used by all other animals. Moreover, insect olfactory proteins are highly divergent, even between closely related insects, with many being unique to a single species. These characteristics make them ideal targets in “next-generation” insecticide development programs and ideal components for species-specific biosensors. The vine mealybug, Planococcus ficus, is a significant vineyard pest due to its role in transmitting the viruses that cause grapevine leafroll disease. Using transcriptomic libraries prepared from male and female mealybugs and a draft genome, we identified and evaluated expression levels of members of the odorant receptor, odorant binding protein, and odorant degrading enzyme gene families. Interestingly, only a subset of the 52 odorant receptor genes encoded in the genome were found to be expressed in adult mealybugs, likely a result of the male’s short life span and inability to feed and the female’s inability to fly. Eight of these odorant receptors were expressed in HEK293 cell lines and tested for their ability to respond to biologically relevant odorant molecules. Of these, PficOR6 responded dose-dependently to the vine mealybug sex pheromone component, lavandulyl senecioate. The discovery of the receptor for this species-specific compound will now allow development of vine mealybug-detecting biosensors and insecticidal chemistries that will likely have much lower off-target effects than traditional compounds.

Funding Support: USDA – Agricultural Research Service