GENETIC-ANALYSIS OF DIFFERENCES IN OVIPOSITION PREFERENCES OF HELIOTHIS-VIRESCENS AND HELIOTHIS-SUBFLEXA (LEPIDOPTERA, NOCTUIDAE)

Heliothis virescens (F.) is a polyphagous pest on cotton soybean, anti tobacco and H. subflexa (Guenee) is a monophagous nonpest on Physalis spp. Oviposition choices of the reciprocal F-1 hybrids of these two species were compared with those of the parental strains to determine sex linkage, quantify niche breadth, and rank host preferences. Strains of H. virescens, H. subflexa, and the reciprocal F-1 hybrids (SV0 and VS0) were each offered a choice of four plants on which to oviposit (cotton, soybean, tobacco, and Physalis angulata). Host preferences were ranked basel oil the proportion of eggs laid on each host. H. virescens overwhelmingly preferred tobacco, H. subflexa preferred Physalis and SV0 and VS0 preferred tobacco. There were no significant differences among strains in their responses to cotton and soybean. Because SV0 and VS0 had similar patterns of preference across hosts, there was no indication of sex linkage. Niche breadth, a measure of the degree of specialization, was calculated for each strain. Under greenhouse conditions, H. virescens had the narrowest ovipositional niche and H. subflexa and the hybrids had broader niches and were similar to each other. When a novel host (Oenothera sp.) was offered to the strains, there was no difference in the responses along strains nor were there changes in preference ranks or diet breadth. The hybrid, despite a major genetic reorganization relative to the parents, did not behave in an unpredictable way.