Laboratory evaluation of the toxicity of mineral oil, Diazinon, Malathion and Chlorpyrifos on ladybird, Cryptolaemus montrouzieri Mulsant (Col.: Coccinellidae)

Acute toxicity of the field recommended concentration of three conventional insecticides (Diazinon, Malathion and Chlorpyrifos) and mineral oil was evaluated on 3^rd and 4^th instar larvae and adults of Cryptolaemus montrouzieri Mulsant. The mortalities caused by the insecticides and mineral oil were significantly different. Diazinon and Malathion with 100% mortality showed the highest toxicity to the different stages of the ladybird. Chlorpyrifos and mineral oil caused less than 30% mortality, while mineral oil had the lowest harmful effect on this predator. Based on LC_50 and LC-90 values 24h after treatment, the male and female adults of C. montrouzieri were more susceptible to Diazinon (701 and 635; 1257 and 1194ppm) than to Chlorpyrifos (4238 and 4316, 5683 and 5480 ppm). Based on International Organization of Biological Control (IOBC) classification, Chlorpyrifos and mineral oil were classified as category 1 (harmless) and Diazinon and Malathion were placed in category 4 (harmful).