EFFICACY OF NONPHEROMONE COMMUNICATION DISRUPTANTS OF CODLING MOTH (CYDIA-POMONELLA) - EFFECT OF PHEROMONE ISOMERS AND OF DISTANCE BETWEEN CALLING FEMALES AND DISPENSERS

Field tests comparing the ability of codlemone, (E,E)-8,10-dodecadien- 1-ol, and isomers of codlemone to disrupt pheromonal communication of codling moth were carried out. In a pear orchard, four nonisomerizing, gray septa dispensers were placed in the upper canopy of each tree co ntaining a trap baited with 10 virgin female codling moths. The dispen sers were at trap height and 70 cm from the edge of each trap. Trap ca tches of released male codling moths in three test areas were compared simultaneously when trees in each of the test areas contained unbaite d dispensers, dispensers with 1 mg of codlemone containing 1% isomers, and dispensers with 1 mg of a test communication disruptant. When the test disruptant was an equilibrium mixture of codlemone and its isome rs (61% codlemone, 39% isomers), the percent communication disruption was 86.8% compared to 68.7% for codlemone (P < 0.001). When the disrup tant was (E,Z)-8,10-dodecadien-1-ol (94% EZ, 3% EE), the percentage di sruption was 86.4% compared to 62.7% for codlemone (P < 0.002). These results show that the previously reported superior disruptant potency (relative to codlemone) of compositions containing codlemone with a hi gh percentage of isomers was not a result of the proximity of the disp ensers to the traps. The percent disruption of compositions of codlemo ne with 10 and 20% isomers was also determined. A plot of percentage d isruption versus logarithm of percentage of nonpheromone isomers in th e mixture from 1% to 97% gave a straight line with R(2) = 0.93.