Five polymorphic tri‐ and tetranucleotide microsatellite loci suitable for population genetic analysis were identified in the cotton bollworm Helicoverpa armigera from two partial phagemid genomic libraries enriched for microsatellite inserts. The overall microsatellite‐cloning efficiency in H. armigera is 2.5%, which is approximately eightfold lower than that for the gadoid fishes (20%) employing the same enrichment protocol, supporting the notion of a relative low frequency of microsatellite sequences in lepidopteran genomes. In addition, a large proportion of cloned microsatellite sequences turned out to be repetitive DNA, thus further increasing the difficulty of developing such markers in butterflies and moths.
Propylaea japonica is an important predatory insect of common cotton pests. To assess the ecological effects of transgenic Bt cotton, expressing Cry1Ac toxin, on this predator, we examined the life history parameters of P. japonica for two generations by feeding them with Bt-resistant Helicoverpa armigera. After ingesting Bt-treated Bt-resistant H. armigera larvae in the third and fourth instar, the body mass and body length of adult P. japonica decreased, a combined effect of poor prey quality and Cry1Ac Bt-toxin may account for these effects. However, larval survivorship and development in these two instars, pupal mortality, fecundity and adult longevity of P. japonica were not affected in both the generations. These results suggest that ingesting Bt-toxin Cry1Ac-treated pests in advanced larval stage might have no significant effect on the fitness of predator P. japonica.
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