Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2008
Publication Date: 2/1/2009
Citation: Ranger, C.M., Reding, M.E., Oliver, J.B., Moyseenko, J.J., Youssef, N.N. 2009. Toxicity of Botanical Formulations to Nursery-Infesting White Grubs (Coleoptera: Scarabaeidae). Journal of Economic Entomology. 102:304-308.
Interpretive Summary: The toxicity of eight botanically-based biopesticides was evaluated against third-instars of the scarab larvae (Coleoptera: Scarabaeidae) Popillia japonica Newman, Rhizotrogus majalis (Razoumowsky), Anomala orientalis Waterhouse, and Cyclocephala borealis Arrow. Soil dip bioassays were used to obtain concentration-mortality data 7 d after treatment of larvae, leading to the calculation of LCB50 Band LCB90B values. A wide range in LCB50B and LCB90B values were exhibited among the formulations. The product Armorex was one of the most active formulations against P. japonica (LCB50 B= 0.42 ml / liter), R. majalis (LCB50 B= 0.48 ml / liter), A. orientalis (LCB50 B= 0.39 ml / liter), and C. borealis (LCB50 B= 0.49 ml / liter). Armorex is comprised of extracts from diverse botanical sources, including 84.5% sesame oil, 2.0% garlic oil, 2.0% clove oil, 1.0% rosemary oil, and 0.5% white pepper extracts. The product Azatin, comprised of 3% azadirachtin, also exhibited high toxicity to P. japonica (LCB50 B= 1.13 ml / liter), R. majalis (LCB50 B= 0.81 ml / liter), and A. orientalis (LCB50 B= 1.87 ml / liter). Veggie Pharm is comprised of extracts from diverse sources, but this product showed the lowest toxicity to P. japonica (LCB50 B= 35.19 ml / liter), R. majalis (LCB50 B= 62.10 ml / liter), A. orientalis (LCB50 B= 43.76 ml / liter), and C. borealis (LCB50 B= 50.24 ml / liter). These results document the potential for botanical formulations to control soil-dwelling white grubs, but blending extracts from diverse botanical sources does not ensure enhanced biological activity.
Technical Abstract: In an attempt to identify reduced-risk insecticides for controlling nursery-infesting white grubs (Coleoptera: Scarabaeidae), the toxicity of eight botanically-based biopesticides was evaluated against the Japanese beetle, European chafer, Oriental beetle, and northern masked chafer. A laboratory-based dip bioassay was used to simulate an insecticidal drench treatment of nursery stock. The dip bioassay provided concentration-mortality responses for all combinations of biopesticides and white grub species. A wide range in toxicity was associated with the formulations, but the degree of product efficacy was relatively consistent across the white grub species. These results indicate certain botanical formulations can potentially be used as an alternative to synthetic insecticides. However, the wide range of ingredients and corresponding toxicity of the formulations tested in this study documents the importance of product composition for obtaining biological activity. Blending extracts from diverse botanical sources does not ensure enhanced biological activity.