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 3rd and 4th 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 LC50 and LC90 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).