Long-lasting insecticide netting for protecting tree stems from attack by ambrosia beetles (Coleoptera: Curculionidae: Scolytinae)

Authors: Ranger, Christopher; Werle, Christopher; SCHULTZ, PETER - Virginia Polytechnic Institution & State University; ADDESSO, KARLA - Tennessee State University; OLIVER, JASON - Tennessee State University; Reding, Michael - Mike

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2019
Publication Date: 12/20/2019
Citation: Ranger, C.M., Werle, C.T., Schultz, P.B., Addesso, K.M., Oliver, J.B., Reding, M.E. 2019. Long-lasting insecticide netting for protecting tree stems from attack by ambrosia beetles (Coleoptera: Curculionidae: Scolytinae). Insects. 11(1):8. https://doi.org/10.3390/insects11010008.
DOI: https://doi.org/10.3390/insects11010008

Interpretive Summary: Ambrosia beetles are destructive wood-boring pests of horticultural trees grown in ornamental nurseries and tree fruit orchards. Conventional insecticides are preventively applied to the stems of trees, but peak beetle activity coincides with the flowering of trees and pollinator activity during spring months. Since ambrosia beetle attacks mainly occur on the stems, we evaluated long-lasting insecticide netting for protecting against opportunistic ambrosia beetles. Container-grown trees were flood-stressed to induce ambrosia beetle attacks and then deployed under field conditions in Ohio, Virginia, Tennessee, and Mississippi. Insecticide-treated netting was wrapped from the base of the stem vertically to the branch junction. The following treatments were tested: (1) flooded tree, (2) flooded tree with untreated netting, (3) flooded tree with treated ‘standard mesh’ or ‘fine mesh’ netting, and (4) non-flooded tree. Treated netting reduced attacks to stems of flooded trees compared to untreated netting and unprotected trees in Mississippi in 2017, and Ohio, Virginia, and Tennessee in 2018. Fewer ambrosia beetles were recovered from trees deployed in Ohio protected with treated netting compared to untreated netting. However, treated netting did not reduce attacks compared to the other treatments in Virginia in 2017, and inconsistent effects occurred in Mississippi in 2018. Thus, long-lasting insecticide netting can provide some degree of protection for stems of vulnerable trees from ambrosia beetle attacks, but additional optimization is needed.

Technical Abstract: Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are destructive wood-boring pests of horticultural trees. Since attacks mainly occur on the stems, we evaluated long-lasting insecticide netting for protecting against opportunistic ambrosia beetles. Cercis canadensis were flood-stressed to induce ambrosia beetle attacks and then deployed under field conditions in Ohio, Virginia, Tennessee, and Mississippi. Deltamethrin-treated netting was wrapped from the base of the stem vertically to the branch junction. The following treatments were tested: (1) flooded tree, (2) flooded tree with untreated netting, (3) flooded tree with treated ‘standard mesh’ or ‘fine mesh’ netting, and (4) non-flooded tree. Treated netting reduced attacks to stems of flooded trees compared to untreated netting and unprotected trees in Mississippi in 2017, and Ohio, Virginia, and Tennessee in 2018. Fewer Anisandrus maiche, Xylosandrus germanus, and Xyleborinus saxesenii were recovered from trees deployed in Ohio protected with treated netting compared to untreated netting. However, treated netting did not reduce attacks compared to the other treatments in Virginia in 2017, and inconsistent effects occurred in Mississippi in 2018. These results indicate long-lasting insecticide netting can provide some degree of protection for stems of vulnerable trees from ambrosia beetle attacks, but additional optimization is needed.