Susceptibility of adult hymenopteran parasitoids of the Nantucket pine tip moth (Lepidoptera: Tortricidae) to broad-spectrum biorational insecticides in a laboratory study

Currently, there is an elevated interest in reducing feeding damage caused by the Nantucket pine tip moth, Rhyaclonia frustrana (Comstock), a common regeneration pest of loblolly pine, Pinus taeda L. The toxicity of several insecticides was tested in a laboratory against four common R. frustrana parasitoids. There were no differences in parasitoid mortality between the control and indoxacarb, treatments. However, the pyrethroids, permethrin and lambda-cyhalothrin, caused significantly more mortality initially (up to 240 min exposure time) than other insecticides. Spinosad was less toxic than the pyrethroids initially, but the spinosad related mortality increased with time until it reached a level similar to the pyrethroids, For the most part, spinosad and the pyrethroids caused more mortality than the control and indoxacarb, treatmtents within the 1-d sample period. These results may have important implications for decisions concerning which insecticides are best suited for reducing pest damage while conserving natural enemies in timber and agricultural systems. Large-scale field trials are required to further define the impacts of these insecticides on natural enemies.