ADVERSE EFFECT OF FENOXYCARB ON REPRODUCTION BY THE CALIFORNIA FIVESPINED IPS, IPS PARACONFUSUS LANIER (COLEOPTERA: SCOLYTIDAE)

Abstract

AbstractThe effects of fenoxycarb, ethyl[2-(p-phenoxyphenoxy)-ethyl]carbamate, an insect growth regulator with juvenile hormone activity, on reproduction in Ips paraconfusus Lanier were investigated. Topical treatment of either females or both sexes of parent beetles with 50 μg of fenoxycarb per insect resulted in a significant reduction in hatching of eggs and numbers of progeny produced by beetles allowed to infest logs of ponderosa pine, Pinus ponderosa Laws. When pairs of beetles were allowed to attack logs that were surface-treated with fenoxycarb, the effects on reproduction at a dose of 100 μg/cm2 of bark surface were comparable to those of a topical treatment at a dose of 50 μg per insect. However, at doses of 1000 or 10 000 μg/cm2 the adverse effects included reductions in the length of egg galleries, fecundity (number of egg niches), and number of freshly laid eggs. Percentage reductions in progeny were 35.8, 82.5, and 95.7 for doses of 100, 1000, and 10 000 μg/cm2, respectively, if brood beetles were allowed to emerge from the logs. This study indicates that fenoxycarb acts as an effective chemosterilant on I. paraconfusus.