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Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/20/2010 Publication Date: 4/4/2011 Citation: Reding, M.E., Ranger, C.M. 2011. Systemic insecticides reduce feeding, survival and fecundity of adult black vine weevils (Coleoptera: Curculionidae) on a variety of ornamental nursery crops. Journal of Economic Entomology. 104(4):405-413. Interpretive Summary: The black vine weevil is a serious pest of ornamental nursery crops, feeding on a wide variety of plant species. Current management of black vine weevil relies on treatments of traditional insecticides, primarily pyrethroids. Multiple foliar sprays are often applied through the season to control the adult stage of this pest. The new neonicotinoid insecticides are more environmentally friendly than materials such as pyrethroids. Neonicotinoids have systemic activity and when applied systemically reduce the potential for worker exposure and drift. Furthermore, a single treatment of a systemically applied neonicotinoid has the potential to provide season-long control of black vine weevils. The current research reports that systemically applied neonicotinoids significantly reduced survival and egg-laying by adult black vine weevils on container-grown nursery crops; and that three different neonicotinoids had activity for at least 7 weeks. Previous research showed that some of these materials prevented infestations of plants by the larval stage of black vine weevils. Therefore, a single systemic treatment of these neonicotinoids should control both larval and adult stages of black vine weevil in nursery crops. This would reduce the number of insecticide treatments compared to the multiple foliar sprays currently used in many areas. Research in commercial nurseries is needed to corroborate results of the controlled experiments. Technical Abstract: A series of bioassays were conducted to test the systemic activity of clothianidin, chlorantraniliprole, dinotefuran, and thiamethoxam against adult black vine weevils (Otiorhynchus sulcatus F.) on Taxus, Heuchera, Astilbe, Sedum, Euonymus, and Rhododendron grown in containers. The insecticides were poured onto the soilless-substrate of the plants. Bioassays were conducted 12 or 13, 26, and 42 days after treatment (DAT) and ran for 7 days; and feeding deterrence, mortality, and weight gain/loss by weevils were evaluated. Foliage was removed from treated and control plants, then placed in arenas with adult black vine weevils. Clothianidin, dinotefuran, and thiamethoxam reduced feeding and weight gain by adult black vine weevils on most plant species. Feeding was deterred by clothianidin, dinotefuran and thiamethoxam through 42 DAT depending on plant species. Clothianidin and dinotefuran had negative impacts on weight gain through 42 DAT depending on plant species. Significant mortality was caused by clothianidin, dinotefuran, and thiamethoxam on Astilbe and by thiamethoxam on Sedum 12 or 13 DAT, respectively. A second group of bioassays was conducted to examine survival and fecundity of adult black vine weevils during prolonged feeding on Heuchera and Taxus systemically treated with dinotefuran or thiamethoxam. Bioassay procedures were similar to above, except bioassays ran continuously for 56 days. Prolonged feeding on dinotefuran and thiamethoxam treated Heuchera and Taxus resulted in significantly greater mortality and reduced number of eggs laid than on control plants. These studies show that systemic neonicotinoids have the potential to suppress black vine weevil populations in containerized nursery crops; and that the systemic activity of neonicotinoids is influenced by plant species. |
