Pyrethroids demonstrate effective insecticidal activity against ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) within tree fruit, nut, and ornamental production systems

Authors: JOSEPH, SHIMAT - University Of Georgia; SCHOOF, STEPHEN - North Carolina State University; HAYTER, JENSEN - North Carolina State University; CHONG, JUANG HORNG - Clemson University; BRINDLEY, JULIE - Virginia Polytechnic Institution & State University; DEL POZO-VALDIVIA, ALEJANDRO - Virginia Polytechnic Institution & State University; Cottrell, Ted; WALGENBACH, JAMES - North Carolina State University; BLAAUW, BRETT - University Of Georgia; Ranger, Christopher

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2025
Publication Date: 8/25/2025
Citation: Joseph, S.V., Schoof, S., Hayter, J., Chong, J., Brindley, J.C., Del Pozo-Valdivia, A.I., Cottrell, T.E., Walgenbach, J.F., Blaauw, B.R., Ranger, C.M. 2025. Pyrethroids demonstrate effective insecticidal activity against ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) within tree fruit, nut, and ornamental production systems. Journal of Economic Entomology. 118(5):2485-2499. https://doi.org/10.1093/jee/toaf198.
DOI: https://doi.org/10.1093/jee/toaf198

Interpretive Summary: The ambrosia beetles are major pests in fruit, nut and ornamental tree nurseries. Females tunnel into stressed trees, creating galleries in the sapwood and heartwood, causing branch dieback and tree death. Current management approach relies on trunk applications of permethrin and bifenthrin to decrease infection risk but, the efficacy of other insecticides has not been thoroughly evaluated. Fourteen trials conducted in five states tested 24 active ingredients. However, only six pyrethroid insecticides (permethrin, bifenthrin, lambda-cyhalothrin, deltamethrin, and cypermethrin) consistently reduced the ambrosia beetle entry holes on treated ethanol-infused bolts compared to nontreated bolts. Dinotefuran significantly reduced ambrosia beetle attacks in one trial. Spinosad, sulfoxaflor + spinetoram, chlorantraniliprole, cyantraniliprole, cyclaniliprole, tetraniliprole, tolfenpyrad, indoxacarb, isocycloseram, carbaryl, Burkholderia spp., Beauveria bassiana, Chromobacterium subtsugae, and Paecilomyces fumosoroseus did not reduce beetle attacks. These results show that there are currently no alternatives to pyrethroid insecticides to protect vulnerable trees from Xylosandrus spp.

Technical Abstract: The ambrosia beetles Xylosandrus crassiusculus (Motschulsky) and Xylosandrus germanus (Blandford) are major pests in fruit, nut and ornamental tree nurseries. Females tunnel into stressed trees, creating galleries in the sapwood and heartwood, causing branch dieback and tree death. Current management approach relies on trunk applications of permethrin and bifenthrin to decrease infection risk. However, the efficacy of other insecticides has not been thoroughly evaluated. Fourteen trials were conducted in five states to evaluate the efficacy of various insecticides as potential management tools in four commodities. Of the 24 active ingredients, only six pyrethroid insecticides (permethrin, bifenthrin, lambda-cyhalothrin, deltamethrin, and cypermethrin) consistently reduced the numbers of entry holes on treated ethanol-infused bolts compared to nontreated bolts. Dinotefuran significantly reduced ambrosia beetle attacks in one trial. Spinosad, sulfoxaflor + spinetoram, chlorantraniliprole, cyantraniliprole, cyclaniliprole, tetraniliprole, tolfenpyrad, indoxacarb, isocycloseram, carbaryl, Burkholderia spp., Beauveria bassiana, Chromobacterium subtsugae, and Paecilomyces fumosoroseus did not reduced beetle attacks. These results show that there are currently no alternatives to pyrethroid insecticides to protect vulnerable trees from Xylosandrus spp.