Inheritance of resistance in diamondback moth, Plutella xylostella to commonly used insecticides.

摘要

In an experiment conducted to determine the extent up to which the insect can gain resistance to a particular insecticide due to continuous exposure for some generations, a laboratory culture of Plutella xylostella was established from pupae and adults collected from cabbage and cauliflower fields in Himachal Pradesh, India. The insecticide treatments comprised cypermethrin, endosulfan and deltamethrin. The third instar larvae were 110 ppm and 449 ppm of LC₅₀ and LC₉₀ values for cypermethrin in the parent generation. After continuous exposure for 12 generations, LC₅₀ and LC₉₀ values were 231 and 1218 ppm, respectively, which were 2.1- and 2.7-folds higher than the parent generation. The results show the development of resistance and hence reduction in the efficacy of cypermethrin in controlling the population of diamondback moth. The LC₅₀ and LC₉₀ values for endosulfan of the third instar larvae were 146 and 708 ppm, respectively, in the parent generation. In the second generation, the larvae have 1.2- and 1.4-fold higher values for LC₅₀ and LC₉₀, respectively. The resistance levels to endosulfan kept on increasing with the number of generations and finally reached up to 2.4 and 3.5-folds more than the parent generation. The third instar larvae of diamondback moth were 5.2 and 21.7 ppm LC₅₀ and LC₉₀ values for deltamethrin in the parent generation. After continuous exposure for 12 generations, diamondback moth developed 1.8- and 2.5-folds higher resistance than the parent generation at LC₅₀ and LC₉₀ levels. Overall, diamondback moth developed more resistance to endosulfan than deltamethrin and cypermethrin.