Chemical composition, toxicity and sublethal effects of Melia azedarach extract on some demographic and biochemical characteristics of the cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae)

Abstract

Abstract One of the most important pests of cabbage and other cruciferous vegetables is the cabbage aphid, Brevicoryne Brassicae L. (Hemiptera: Aphidae). This aphid produces multiple generations per year, each generation producing large numbers of nymphs that are resistant to a variety of chemical insecticides. In this study, sublethal effects of Melia azedarach extract was investigated on some demographic and biochemical parameters of B. brassicae. The bioassay results showed that the LC10, LC20, and LC50 values ​​were 0.68, 1.16, and 3.42 µg/ml, respectively. Compared to controls, the sublethal doses caused significantly reduced gross reproductive rate (GRR), net reproductive rate (R0), intrinsic rate of increase (rm), finite rate of increase (λ), intrinsic rate of birth (b), intrinsic rate of death (d), weekly growth rate (rw), reproductive rate and adult longevity. Meanwhile, the mean generation time (T) and population doubling time (DT) of this aphid increased significantly. Additionally, sublethal doses reduced the energy reserves of this pest compared to controls. Our results help evaluate the overall impact of M. azedarach extract on B. brassicae and have important implications for the judicious use of botanical insecticides cabbage aphid control.