Preliminary biological studies on the pheromone produced by male Acanthoscelides obtectus (Say) (Coleoptera, Bruchidae)

Abstract

Virgin female Acanthoscelides obtectus (Say) placed in a closed 12·5 cm Petri dish were attracted to a caged male by a pheromone which could be extracted with hexane and was extremely stable in solution. Surfaces which had been exposed to males attracted virgin females. The male did not respond to a caged female although on coming into contact with a free female he usually pursued her and attempted to mate. Mating lasted about 10 min after which females usually resisted any further attempts made by males during the 8 hr period of observation. After mating or removal of antennae females were not attracted by caged males and remained unresponsive for the rest of their lives. Virgin females given the choice between male pheromone and the smell of beans chose the former. Male extract presented on a variety of substrates usually attracted virgin females but a few failures occurred. When extract was run on a thin layer chromatogram and presented to virgin females they were only attracted to the region carrying the allenic ester (−)-methyl n-tetradeca-trans-2,4,5-trienoate, and extract without it (removed using chromatographic techniques) proved inactive. The allenic ester therefore appears to be at least closely related to the pheromone.