Effects of Hexaflumuron on Transovarial, Ovicidal, and Progeny Development of Aubeonymus mariaefranciscae (Coleoptera: Curculionidae)

Abstract

Topical and foliar exposure of hexaflumuron on field-collected adults of Aubeonymus mariaefranciscae Roudier, applied at 0.03 μ g (AI) per adult and 31 μ g (AI) per sugar beet leaf, respectively, resulted in significant inhibition of egg hatch. Both sexes topically treated a50 d before the start of oviposition had inhibited egg hatch for a73% of the total ovipositon period, but was 43% for adults exposed to hexaflumuron-treated sugar beet leaves. Inhibition was lower for topical (56%) and foliar (22%) applications when weevils were treated soon after onset of oviposition. Period of egg hatch inhibition by topical application was 1.5 times greater when both sexes were exposed and mated together compared with exposed females mated with untreated males. No egg hatch inhibition was observed when treated males mated with untreated females. Mortality of treated eggs (0–24 h old) on hexaflumuron-treated filter paper was significantly greater compared with mortality of eggs 1–6 d old. This suggested that age group was a critical stage for penetration of hexaflumuron or chitin synthesis. Topical application of hexaflumuron to ovipositing weevils suppressed survival of F1 larvae (6% survival at 1st instar and all died at 3rd instar) and only a 4% survival (at pupal stage) was obtained with foliar application.