Sex pheromone of yellow scale, Aonidiella citrina (Homoptera: Diaspididae): Evaluation as an IPM tactic

The effects of dose and field longevity of lures treated with synthetic female yellow scale sex pheromone ((5E)-6-isopropyl-3,9-dimethyl-5,8-decadienyl acetate) were evaluated for monitoring flight activity of male yellow scale, Aonidiella citrina (Coquillett). Pheromone doses of 1-200 μg per lure attracted large numbers of males. Lower doses (1-5 μg per lure) generally attracted fewer males, but trap counts unequivocally showed the beginnings and peaks in male flight activity at both low and high population densities. Furthermore, the low-dose pheromone traps that collected fewer individuals were easier and less time-consuming to assess, and so the lower doses are recommended for monitoring phenology and population densities. In field longevity tests, pheromone lures continued to attract sufficient numbers of male scale to follow population trends for up to 4 months. Insecticide applications suppressed the number of male scale captured on pheromone cards. A 1989 pheromone trap survey of yellow scale in Tulare County, California demonstrated that yellow scale was distributed throughout the citrus growing region of that county, and was especially heavy in the area between Porterville and Terra Bella.