Pheromone pre-exposure and mating modulate codling moth (Lepidoptera: Tortricidae) response to host plant volatiles

1 Two codling moth Cydia pomonella kairomonal attractants, ethyl (E,Z)-2,4-decadienoate (pear ester) and (E)-beta-farnesene, were tested in an insecticide-sprayed apple orchard and an orchard treated for mating disruption with synthetic pheromone (E,E)-8,10-dodecadienol (codlemone). Male captures with pear ester were higher in the pheromone- treated than in the insecticide-treated orchard, whereas captures with (E)-beta-farnesene were not different. Subsequent wind tunnel experiments confirmed that pre-exposure to sex pheromone codlemone increased the behavioural response of codling moth males to pear ester. This supports the idea that male attraction to the plant volatile pear ester and sex pheromone codlemone is mediated through the same sensory channels. 2 Pear ester is a bisexual codling moth attractant and even captures of female moths were significantly increased in the pheromone-treated orchard. In the laboratory wind tunnel, pheromone pre-exposure had no effect on female response to pear ester, but significantly more mated than unmated codling moth females flew upwind towards a pear ester source. Differences in mating status in insecticide-treated vs. pheromone-treated orchards may thus account for the differences in female trap captures with pear ester. 3 These findings are important with respect to monitoring of codling moth with pear ester in mating disruption orchards. They also emphasize the importance of host plant volatiles in pheromone-mediated mating disruption, which has been neglected to date.