Transovarial activity of the chitin synthesis inhibitor novaluron on egg hatch and subsequent development of larvae of Tribolium castaneum.

摘要

The effects of the chitin synthesis inhibitor (CSI) novaluron on egg hatch and on larval development of Tribolium castaneum at concentrations of 1.0, 0.3, 0.2 or 0.1 ppm were tested. The effect of novaluron at low concentrations depended strongly on the exposure period. At 0.3 ppm, egg hatch of T. castaneum was totally inhibited after 28 days; at 0.2 ppm, the effect was much less, but inhibition increased progressively to 66% in the 35-day experiment; and at 0.1 ppm novaluron was ineffective. The viability of the larvae that hatched from the laid ova and developed on untreated flour was also dependent on concentration of novaluron and exposure time. The exposure of T. castaneum adults to novaluron-treated flour at 0.3 ppm for 8 days or at 0.2 ppm for 36 days caused 100 or 97.5% mortality, respectively. At both 0.3 and 0.2 ppm, larval deaths were mainly in the first instar. Exposure of T. castaneum adults to treated flour may serve as a good model for evaluating the effect of CSI on internal feeders, especially Sitophilus oryzae. The present study contributes to our understanding of CSI transovarial activity against internal stored product coleopterans whose larval stage develops inside the grain without contact with the toxicants.