Laboratory assessment of some chemical insecticides toxicity on Brevicoryne brassicae (Hemiptera: Aphididae) and their selectivity for its predator, Hippodamia variegata (Coleoptera: Coccinellidae)

The cabbage aphid, Brevicoryne brassicae, is a serious pest of cruciferous plants, causing worldwide economic damage, notably due to its resistance to many commonly used insecticides. Therefore, the development of integrated pest management (IPM) approaches that include novel effective insecticides against this pest is essential. This study evaluated the toxicity of insecticides flupyradifurone, fluxametamide, and dinotefuran against adults of B. brassicae after 24 hours using the leaf-dipping method. Probit analysis revealed flupyradifurone as the most effective insecticide against the pest, with an LC50 value of 58.16 mg/L. However, the sublethal concentration (LC25) effect of this novel insecticide on population growth parameters was estimated using the age-stage, two-sex life table theory method. The sublethal concentration (LC25= 21.65 mg/L) of flupyradifurone reduced female adult longevity and fecundity compared to the control treatment. The values of the intrinsic rate of increase were 5.236 and 24.345 nymphs per female, the net reproductive rate was 0.125 and 0.277 per day, and the finite rate of increase was 1.134 and 1.319 per day with LC25 of flupyradifurone treatment and control, respectively. Dinotefuran with LC50 values of 244.50 and 1005.17 mg/L, had the highest toxicity on third instar larvae and adults of Hippodamia variegata, respectively. The selectivity ratio and hazard quotient values indicated that all three insecticides are selective and safe for the predator H. variegata. By conducting more experiments in the future, simultaneous use of insecticides flupyradifurone, dinotefuran, fluxametamide and H. variegate can be recommended in the integrated management of B. brassicae.