Transovarial effects of insect growth regulators on Stephanitis pyrioides (Hemiptera: Tingidae)

BACKGROUND Azalea lace bug, Stephanitis pyrioides (Scott) (Hemiptera: Tingidae) is a serious insect pest of azaleas (Rhododendron L. spp.) in the USA. S. pyrioides feeding causes chlorosis, which affects the aesthetic value and marketability of azalea plants. Management of S. pyrioides primarily involves neonicotinoid insecticides and their use has been drastically reduced or discontinued. Insect growth regulators (IGRs) are known to elicit transovarial activity as IGR-exposed adults produce non-viable eggs, which is not documented for S. pyrioides. Thus, transovarial activity of novaluron, azadirachtin, pyriproxyfen and buprofezin has been explored against S. pyrioides. RESULTS A low number of S. pyrioides young instars was produced when adults were exposed to topical novaluron compared with non-treated adults. When adults contacted dried residues of novaluron and buprofezin, production of young instars was reduced relative to non-treated controls. When insects exposed to 1.0x and < 1.0x doses of novaluron were compared, the number of young instars produced was similar. CONCLUSION Transovarial activity was elicited in S. pyrioides when adults were exposed to IGRs, especially novaluron. When adults were exposed to < 1.0x (up to 0.25x) and 1.0x doses of novaluron, the transovarial effect was similar. (c) 2019 Society of Chemical Industry