نوع مقاله : مقاله پژوهشی
عنوان مقاله [English]
The lethal and sublethal effects of chlorpyrifos+oil, abamectin, and chlorpyrifos+abamectin+oil on the immature stages of Cryptolaemus montrouzieri Mulsant were investigated under laboratory conditions. Chlorpyriphos was applied at 500, 1000 and 2000 ppm with 1% oil and abamectin at 500, 100, and 200 ppm concentrations on fourth instar larvae through three exposure methods, including topical direct contact, residual contact and feeding on sprayed preys. The eggs of C. montrouzieri treated via dipping in pesticide solutions. Dipping eggs in pesticide solutions affected significantly their hatching rate, first instars larvae survival, and pupal weight. The lowest egg hatching percent (29 percent) and pupal weight (9.8 mg) were observed in chlorpyriphos 2000 ppm+abamectin 200 ppm+oil. Survival of the fourth instar larvae and pupal developmental period and weight were also significantly affected in each exposure method. The lowest survival of fourth instar larvae (50 percent) and longest pupal duration (7.0 days) were obtained in topical contact with chlorpyriphos 2000 ppm+abamectin 200 ppm+oil. In conclusion, because of the adverse effects of chlorpyriphos on the development of immature stages of the ladybird, replacing it with a safer pesticide is necessary to increase the compatibility of biological and chemical control programs in citrus orchards of northern Iran.