Action des substances soufrées volatiles du poireau (Allium porrum) sur la ponte d'Acrolepiopsis assectella (Lepidoptera: Hyponomeutoïdea): prépondérance des thiosulfinates

Abstract

When the leaves of Allium species are broken, it is usually considered that diffusion of alkyl disulfides occurs. These stable compounds are supposedly formed by intracellular reduction of the unstable thiosulfinates. As thiosulfinates are also converted into disulfides by spontaneous disproportionation, the authors suppose that thiosulfinates would be emitted from the vegetal cell and next would be slowly disproportionated into disulfides. This hypothesis is much more consistent with the assumption that volatile substances yield spatial–temporal information and facilitate the location of the plant by the leek moth. Therefore, the effect of dimethyl or dipropyl thiosulfinates on oviposition behaviour of the leek moth is tested. Daily and total oviposition and number of laying females are compared in four groups of mated females: without volatile components of leek (Allium porrum), with disulfides, with thiosulfinates, and with leek volatile substances. In all cases, insects are more sensitive to the labile thiosulfinates than to the stable disulfides or even sometimes to leek volatile substances. These results strengthen our hypothesis that the thiosulfinates diffuse into the air and seem to indicate that labile chemical substances are significant in inter- or intra-specific communication in insects.