ORIGIN AND IDENTIFICATION OF BACTERIA WHICH PRODUCE KAIROMONES IN THEFRASS OF ACROLEPIOPSIS-ASSECTELLA (LEP, HYPONOMEUTOIDEA)

The volatiles used by the parasitoid Diadromus pulchellus to find its host, the leek moth, are produced by the bacteria developing in the fr ass of the host larvae. The origin and the nature of these bacteria we re investigated. Samples were taken from healthy leeks and from infest ed leeks in the field, as well as from the frass of larvae reared in t he laboratory either on the host plant or on an artificial diet. The v arious species of bacteria identified were cultured in the presence of precursors of leek sulphur volatiles and their volatile emissions wer e analysed. Klebsiella oxytoca and various Bacillus, common decomposer s of plant matter, were the principal species producing active volatil es which were alkyl disulphides.