Efficacy of two insecticides in the protection of loblolly pines from bark beetles in Georgia

We studied the efficacy of two insecticides in preventing colonization by bark beetles on loblolly pines in Georgia. We specifically targeted Ips avulsus, Ips grandicollis, Ips calligraphus, and Dendroctonus terebrans, which are major bark beetle species in pine plantations and woodlands. Fifteen loblolly pine trees were girdled and treated with dicamba herbicide in July 2009 to accelerate their decline. Five trees were randomly assigned to either of the following treatments: 1) control with no insecticide; 2) bole sprayed with bifenthrin insecticide; and 3) bole sprayed with carbaryl insecticide. Racemic ipsenol and ipsdienol were also attached to each tree to maximize beetle pressure on trees. Single and double-pane window traps were attached to the boles at two heights (5 and 15 m) to assess their efficiency in capturing beetles. External evidence of bark beetle activity was also assessed once a month. Preliminary results indicate that all the trees died within a month of girdling, and that significantly less bark beetle activity was observed on insecticide-treated trees. Both insecticide products were effective over the four month period, and differed only slightly in terms of beetle colonization activities. There were little differences in beetle catches between single and double pane window traps, indicating that either traps can be used to maximize trap catches in future studies.