Effects of two carbamates on infective juveniles of Steinernema carpocapsae all strain and Steinernema feltiae Umea strain

Laboratory bioassays were conducted to determine the effects of two carbamates, carbofuran (an acetylcholinesterase inhibitor) and fenoxycarb (a juvenile hormone analog), on survival and infectivity of the infective juveniles (IJ) of Steinernema feltiae Umea strain and Steinernema carpocapsae All strain. Both insecticides caused mortality of IJ in a dose-related fashion. The two nematode species were equally sensitive to fenoxycarb (LD50 ca. 0.03 mg/ml). Whereas IJ of S. feltiae were several orders of magnitude more sensitive to carbofuran (LD50 <= 0.2 micro g/ml) than to fenoxycarb. S. carpocapsae IJ displayed approximately the same degree of sensitivity to carbofuran (LD50 0.01-0.03 mg/ml) as they did toward fenoxycarb. Toxicity of the carbamates was the same at all exposure periods from 24 to 168 hours' duration. Determinations of infective doses of nematodes required to cause 50% mortality of Galleria mellonella larvae showed that the infectivity of IJ that survived exposure to either of the two carbamates was not compromised by treatment..