Relative Efficacy of some Insecticides Against Defoliating Beetle, Brahmina coriacea on Apple

Eight insecticides were evaluated for their relative toxicity under laboratory conditions, and residual toxicity under field conditions against Brahmina coriacea (Hope) adults during July 1990 and 1991. The order of toxicity on the basis of LC50 values and relative toxicity in relation to malathion was: methyl-parathion (0.0062%, 37.7) > monocrotophos (0.0086%, 27.2) > cypermethrin (0.0098, 26.0) > deltamethrin = fenitrothion (0.001%, 21.7) > fenvalerate (0.012%, 193) > carbarjrl (0.0312%, 754) > malathion (0.234%, 1). Residual toxicity of synthetic pyrethroids and monocrotophos was greater than for methyl-parathion. Three days after spraying (DAS), maximum mortality was recorded with fenvalerate (60.2%) and deltamethrin (59.3%). At 10 DAS, toxicity of monocrotophos was significantly greater (19.4%) than that of pyrethroids (11–15%). Similar persistence trends were recorded in both years.