Antigonadotropic effects of precocene 2: allaticidal action in females of Nilaparvata lugens (Stal)
2000
Pradeep, A.R. (University of Calicut, Kerala - 673 635 (India))Nair, V.S.K.
Exposure of day 0, 1, 2, and 3 fifth instar nymphs and newly ecdysed brachypterous females of Nilaparvata lugens to different doses of the anti-juvenile hormone agent, precocene 2 (P2) residue inhibited ovarian growth and oocyte maturation, reduced fecundity and induced sterility in a dose-dependent manner. High dose of 5 micro g/sq cm induced complete sterility. Severe histopathological alterations were observed in the ovariole amd oocytes of insects treated with high doses. Follicular epithelial cells invaded ooplasm. Uncontrolled multiplication resulted in hyperplasia of the epithelia. Exposure of P2-pretreated nymphs to, juvenile hormone analogue (3 micro g JHA/sq cm) did not enhance fecundity, indicating the requirement of intact corpora allata later in the final instar for pre-ecdysial ovarian growth and maintenance. But JHA treatment to P2-pretreated adults restored normal rate of fecundity, revealing P2-induced JH deficiency as the cause of infecundity, P2 induced significant reduction in size of corpus allatum and cellular degeneration in the treated insects. In fecundity, ovarian histopathology and allatal atrophy apparently suggest that the observed anti-juvenile hormone effects of P2 in N. lugens female are due to its systematic allaticidal activity
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