OVIPOSITION SITE SELECTION BY THE DIAMONDBACK MOTH, PLUTELLA-XYLOSTELLA (L) (LEPIDOPTERA, PLUTELLIDAE)

Although Plutella xylostella (L.) is a worldwide pest of cruciferous c rops, relatively little is known about its oviposition behavior. This study was undertaken to provide necessary information about mechanisms involved in P. xylostella host selection. Four oviposition behaviors were described. Moths were given artificial substrates treated with wa ter, sinigrin, or Brassica napus (cv. Westar) squashes, combined with B. napus volatiles and/or grooves in the substrate. No eggs were depos ited in the absence of olfactory and gustatory stimuli. Moths given gu statory but not olfactory stimuli deposited similar numbers of eggs bu t spent significantly more time performing olfactory-related behaviors . Conversely, moths given olfactory but not gustatory stimuli did not oviposit. Substrate grooves did not influence egg numbers but appeared to influence egg location. The order in which oviposition behaviors o ccur and the relative importance of stimuli type are discussed.