Field evidence of synergism and inhibition in the sesiidae sex pheromone system

The E,Z, Z,Z, and Z,E geometric isomers of 3,13 octadecadien-1-ol acetate were used singly and in binary combinations to trap sesiids in Wisconsin cherry orchards. The Z,E isomer alone did not capture any sesiids. A synergistic effect, however, of Z,E on Synanthedon pictipes response to its pheromone E,Z was demonstrated for the first time. Strong inhibitory effects of the Z,Z isomer on S. pictipes response to E,Z, and of the E,Z isomer on S. scitula response to Z,Z, were found. As little as 0.5% of Z,Z in E,Z completely inhibited the S. pictipes response. This species' response was also reduced by 85% when Z,Z was evaporated at 4 points, each ca. 6 m from the pheromone trap. Consistencies and discrepancies of the data with relevant experimental results from other geographical areas are briefly discussed.