Identification of female sex pheromone of the legume pod borer, Maruca vitrata and antagonistic effects of geometrical isomers

An EAD-active component in a female abdominal tip extract of the legume pod borer, Maruca vitrata (Fabricius) (= M. testulalis), was identified as (E, E)-10,12-hexadecadienal (E10,E12-16:Ald). In laboratory bioassays, the puri fied synthetic E10,E12-16:Ald with 99% isomeric purity had attractancy to m ale moths equal to the crude extract. However, the unpurified chemical with 92% isomeric purity did not show any attractancy. Addition of 0.1 ng EZ is omer or 1 ng of EZ, ZE, or ZZ isomers of 10,12-16:Aid to 1 ng of the purifi ed synthetic pheromone antagonized its attractancy as did addition of each isomer to 1 female equivalent of the crude extract. These results suggest t hat it is necessary to develop formulation and release techniques that main tain extremely high isomeric purity of the synthetic pheromone for male tra pping in the field.