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 purified synthetic E10,E12-16:Ald with 99% isomeric purity had attractancy to male 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 isomer or 1 ng of EZ, ZE, or ZZ isomers of 10,12-16:Aid to 1 ng of the purified synthetic pheromone antagonized its attractancy as did addition of each isomer to 1 female equivalent of the crude extract. These results suggest that it is necessary to develop formulation and release techniques that maintain extremely high isomeric purity of the synthetic pheromone for male trapping in the field.