Indirect Effect of Insecticides Used in Pecan Orchards to Larvae of Chrysoperla rufilabris (Neuroptera: Chrysopidae)

Eight insecticides at two concentrations (low and high) were tested for toxicity to first, second, and third instars of Chrysoperla rufilabris (Burmeister). Lindane (0.65 and 1.3 g actual insecticide AI/l), endosulfan (0.375 and 0.75 g AI/l), carbaryl (1.2 and 2.4 g AI/l), azinphos-methyl (1.0 and 2.0 g AI/l, malathion (0.9 and 1.8 g AI/l), methomyl (0.225 and 0.45 g AI/l), phosmet (0.375 and 0.75 g AI/l), and esfenvalerate (0.0.15 and 0.03 g AI/l) treated cowpea aphids (Aphis craccivora Koch) were fed to the lacewing larvae in the laboratory. Among tested insecticides, azinphos-methyl was the most toxic insecticide to larvae at the low and high rates and was classified as moderately harmful. Lindane and carbaryl were slightly harmful; endosulfan, malathion, methomyl, phosmet, and esfenvalerate were harmless. In most cases the first instar larvae were the most susceptible to the insecticides tested. Both rates caused similar mortality of C. rufilabris larvae after 48 h of feeding with the exception of azinphos-methyl and methomyl which caused higher mortality at the high rate.