Attraction of Spathius Agrili Yang (Hymenoptera: Eulophidae) to Male-Produced "Aggregation-sex Pheromone": Differences Between the Sexes and Mating Status

Male and female Spathius agrili Yang were tested for attraction to the synthetic male pheromone. Lures consisting of a 3-component pheromone blend were placed in the center of a white filter paper target used to activate upwind flight in the wind tunnel. When virgin males and females were tested for attraction, both sexes were attracted to the lure prior to mating. However, only males were attracted to the pheromone lures after mating. In another experiment, of females that flew to the lure as virgins, half were subsequently mated and the other half were not, and mated females were no longer attracted. Then both mated and virgin females were provided with host material (emerald ash borer larvae in sticks of ash) to determine if oviposition affected attraction. They were supplied with fresh hosts ad libidum and subsequently tested for attraction for 55 days, and results showed that oviposition did not affect attraction to the pheromone. The key factor in attraction to the pheromone was mating. Because this pheromone is released by one sex and is attractive to both sexes for the purpose of mating, it qualifies as an "aggregation-sex pheromone".