CHEMICAL ECOLOGY Dose–Response of Codling Moth (Lepidoptera: Tortricidae) to Ethyl (E, Z)-2,4-Decadienoate in Apple Orchards Treated with Sex Pheromone Dispensers

Studieswere conducted in apple,MalusdomesticaBorkhausen, orchards to evaluate the attractiveness of the kairomone, ethyl (E, Z)-2,4-decadienoate (pear ester), loaded at various rates into gray halobutyl septa, to adult codling moth, Cydia pomonella L. All studies were conducted in orchards treated with sex pheromone mating disruption. Lure loadings from 0.01 g to 50.0 mg were evaluated in 12 orchard plots in 1999. Lures loaded with 1.0Ð50.0 and 0.1Ð50.0 mg caught signiÞcantly more male and female moths than the blank control, respectively. Field doseÐresponse studies were repeated with Þve lure rates (0.1Ð40.0 mg) of pear ester during four periods during the 2000 season. SigniÞcant seasonal date and rate effects were found for the capture of males and female moths. The 0.1-mg lure caught signiÞcantly fewer males than the 1.0-, 3.0-, and 40.0-mg lures. The 40.0-mg lure caught signiÞcantly fewer femalemoths than the 1.0and 3.0-mg lures. The 3.0-mg lure caught a higher proportion of virgin females than the 10.0and 40.0-mg lures. The attractiveness of the 1.0 and 3.0 mg pear ester loadings were compared with a sex pheromone lure during a 10-wk trial in 2002. Both pear ester lures caught signiÞcantly fewer moths than the sex pheromone lure during the Þrst 4 wk of the study and over the entire 10-wk period. However, no difference among lures occurred during week 5, and the 3.0-mg lure caught signiÞcantly more moths than the sex pheromone lure during week 6. The 3.0-mg lure caught a signiÞcantly higher proportion of female moths and a higher proportion of virgin female moths than the 1.0-mg lure. These studies suggest that the optimal loading of pear ester for capture of codling moth in mating disrupted apple orchards likely depends on the speciÞc objectives of the monitoring program.