Susceptibility of adult hymenopteran parasitoids of the Nantucket pine tipmoth (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 r egeneration pest of loblolly pine, Pinus taeda L. The toxicity of several i nsecticides was tested in a laboratory against four common R. frustrana par asitoids. There were no differences in parasitoid mortality between the con trol and indoxacarb, treatments. However, the pyrethroids, permethrin and l ambda-cyhalothrin, caused significantly more mortality initially (up to 240 min exposure time) than other insecticides. Spinosad was less toxic than t he pyrethroids initially, but the spinosad related mortality increased with time until it reached a level similar to the pyrethroids, For the most par t, spinosad and the pyrethroids caused more mortality than the control and indoxacarb, treatmtents within the 1-d sample period. These results may hav e important implications for decisions concerning which insecticides are be st suited for reducing pest damage while conserving natural enemies in timb er and agricultural systems. Large-scale field trials are required to furth er define the impacts of these insecticides on natural enemies.