Abstract
Topical application of insect growth regulators (IGRs) on older L3 last stage larvae of Adoxophyes orana (Fischler von Rosenstamm) eventually inhibited adult ecdysis. Applications on young L3 larvae only gave this effect when pupae retained juvenile characters scored 4 or higher on a 7-point scale. Reproductive activities of moths emerging from pupae scored 0 (no effect) to 3, correlated negatively with the pupal score. IGR effects on both sexes were analyzed by allowing matings only between a treated and an untreated sex partner. Males showed a strongly reduced mating activity when they emerged from score-2 or -3 pupae. Also, ovarian development and egg production were reduced in females from score-2 pupae; higher scores coincided with defects in the ovaries. Whenever both sex partners resulted from pupae scored 1 or higher, a dramatic decrease in the number of offspring followed. Both IGRs showed only low ovicidal potentials at high concentrations and with young eggs. Delayed effects on the metamorphosis of 2nd-generation larvae were not observed.
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