Biological parameters of the cabbage aphid, Brevicoryne brassicae, encountering the sublethal concentration (LC25) of chlorfluazuron

Brevicoryne brassicae (L.) is one of the important and economic pests of Cole crops in Iran. One of the main methods to protect plants against aphids is using chemical pesticides. In this study, the sublethal effects of Chlorfluazuron was evaluated on the population growth parameters of cabbage aphid under greenhouse condition. The method used in the experiments was insecticide spraying on the leaves containing aphids. LC25 (105.60 ppm) concentration was used to investigate the sublethal effect of insecticides on aphid. The results showed that lifespan/longevity and fertility of the treated adult aphids were significantly affected by the sublethal concentration. Total longevity reduced from 12.78 days in control treatment to 8.14 days in sublethal concentration. The results of present study indicated that sublethal concentration also affected progeny of treated adult aphids. Accordingly, the sublethal concentration of the studied insecticide decreased the values of the intrinsic rate of increase (r) compared to the control treatment. Other population growth parameters such as net reproductive rate (R0), finite rate of increase (λ) and gross reproductive rate (GRR) were also significantly lower than the control. Decreasing the growth rate in sublethal treatment increased mean generation time (T). Based on research findings, Chlorfluazuron can be suitable for use in the management of the cabbage aphid, other than the recommended pest (diamondback moth).