Transovarial effect of novaluron: persistence and residual effects on Stephanitis pyrioides (Hemiptera: Tingidae)

Abstract

AbstractStephanitis pyrioides (Scott) (Hemiptera: Tingidae) is an important insect pest of azaleas, Rhododendron Linnaeus spp. (Ericaceae), in the United States of America. Because neonicotinoids, insecticides traditionally used against S. pyrioides, pose a risk to pollinators and natural enemies, nursery growers have reduced neonicotinoid use and are seeking alternative management options. Novaluron, an insect growth regulator, elicits a transovarial effect by reducing the viability of eggs after exposure to S. pyrioides adults. However, stability and persistence of transovarial effects on adults following exposure are not clear. The objectives of this study were to determine (1) the persistence of the transovarial effect of novaluron for up to three weeks after a single adult exposure and (2) the residual activity of aged novaluron residues eliciting a transovarial effect against S. pyrioides after a single application. Stephanitis pyrioides density was significantly lower in the novaluron-treated adults than in the nontreated controls for up to 21 days. The novaluron residues deposited on azalea foliage aged up to 32 days significantly reduced the number of S. pyrioides nymphs compared to that of the nontreated control. There was no significant difference in the number of nymphs among the 7-, 17-, and 32-day-old novaluron treatments relative to the nontreated control.