Document Type : Pest Management
Authors
Abstract
The Colorado potato beetle, Leptinotarsa decemlineata Say (Col.: Chrysomelidae), is the most harmful insect pest in potato fields. Precocene, a juvenile hormone inhibitor, has cytotoxic effects on insect’s corpora allata. The effects of precocene-І and precocene-IІ were tested on the 2nd larval instar of L. decemlineata by topical application in laboratory. The results showed that precocene-І and precocene-IІ increased larval mortality and developmental period, but had effect on pupal period. Both larval mortality and developmental period were directly correlated with precocene concentration. The most effective concentration of precocene was 50 mg/larva, which caused 95% (precocene-IІ) and 100% (precocene-І) mortality during larval period. Precocene did not influence number of larval instars and molting, but it led to early formation of pupal characteristic on larvae and formation of adultoids. Leptinotarsa decemlineata treated with precocene were also showed other severe morphological abnormalities, such as size reduction, body segmentation disturbance, strong deformation or complete reduction of wings and elytra, and persistance of old cuticle.
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