Sublethal effects of beta-cypermethrin on the bird cherry-oat aphid Rhopalosiphum padi (Hemiptera: Aphididae)

Abstract Rhopalosiphum padi is a sap-sucking aphid and an important pest of wheat that causes considerable yield loss. Beta-cypermethrin, a synthetic pyrethroid pesticide, has a broad insecticide spectrum and is considered effective for aphid control, while its residual concentrations may have sublethal effects on R. padi . Here, the sublethal effects of beta-cypermethrin on R. padi were conducted under laboratory conditions. The acute toxicity test showed that LC 10 , LC 20 , and LC 25 of beta-cypermethrin to R. padi adults were 0.003, 0.031 and 0.079 mg L −1 , respectively. The pre-adult survival rate was significantly reduced by all three concentrations. LC 20 significantly extended the development duration of 1st instar nymphs, pre-oviposition period, and oviposition period of R. padi . The adult longevity was also reduced by LC 25 . However, the fecundity did not differ between the beta-cypermethrin treatment and control. For life table parameters, both the finite rate ( λ ) and intrinsic rate of increase ( r ) decreased at LC 10 and LC 20 , as well as the net reproductive rate ( R 0 ) reduced at LC 10 and LC 25 , while mean generation time ( T ) increased at LC 20 . Thus, at the concentrations of beta-cypermethrin tested here, there were negative impacts on R. padi fitness by decreased pre-adult survival rate, λ , r , and R 0 , and delayed the development of some stages and increased T .