We have made major progress towards identifying the sex pheromone of the grape mealybug, the last of the four mealybug species of importance to the wine and grape industries in the western United States that we had targeted for pheromone identification and development. Key advances included:
- Development of coupled gas chromatography-electroantennogram detection techniques that allowed us to use the antennae of male grape mealybugs as living detectors has clearly shown that extracts from virgin females contain a single pheromone component that elicits strong and consistent responses from the antennae of males. Thus, we have unequivocally located the pheromone compound in the extracts.
- A combination of microchemical tests, mass spectrometric analysis, and gas chromatographic analyses have shown that the compound is an ester of a previously unknown monoterpene alcohol.
- By combining pheromone extracts collected over several years, we have a few micrograms of the pheromone. After purification by preparative gas chromatography, this should be provide sufficient material for final, unequivocal identification of the pheromone within the next few weeks.
Thus, the pheromone of this worldwide pest, which has eluded us for five years, if finally within reach, and should be identified and synthesized, with field tests underway, during the 2007 crop year.
Ongoing field trials with the longtailed and obscure mealybug pheromones in California, South America, New Zealand, and Australia, in vineyards, nurseries, and cotton, have demonstrated that these pheromones are highly attractive to male mealybugs, as with the pheromone of the vine mealybug that we identified earlier in this project. There are indications that trap catches of longtailed mealybug show some degree of seasonality, with better catches during the cooler fall months in California.