OVIPOSITIONAL RESPONSE OF 3 HELIOTHIS SPECIES (LEPIDOPTERA, NOCTUIDAE) TO ALLELOCHEMICALS FROM CULTIVATED AND WILD HOST PLANTS

The role of plant allelochemicals on the oviposition behavior of Heliothis virescens (F.), H. subflexa (Guenee), and H. zea (Boddie) was investigated in the laboratory using a "choice" bioassay system. Fresh young leaves of tobacco, Desmodium tortuosum (Swartz) de Candolle, groundcherry (Physalis angulata L.), and cotton (Gossypium hirsutum L.) squares (flower buds) were washed in methylene chloride or methanol, concentrated to 1 g equivalent of washed material, and applied to a cloth oviposition substrate. Each of the extracts-including groundcherry, a nonhost-stimulated oviposition by H. virescens. H. subflexa were stimulated to oviposit by groundcherry extract, its normal host, and extract from cotton squares, a nonhost. None of the extracts stimulated oviposition by H. zea, although all except groundcherry were from reported hosts. The sensitivity of the bioassay was confirmed by giving H. virescens and H. subflexa an opportunity to choose between extracts that showed stimulant qualities when tested independently versus only solvent-treated controls. In these tests, tobacco showed the highest level of stimulant activity for H. virescens; groundcherry exhibited the highest level of stimulation for H. subflexa. © 1990 Plenum Publishing Corporation.