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

Zhang, Qing-Qing, Li, Wen-Qiang, Lu, Zeng-Bin, Li, Li-Li, Yu, Yi, Li, Chao, Men, Xing-Yuan
Journal of Asia-Pacific entomology 2019 v.22 no.3 pp. 693-698
Rhopalosiphum padi, acute toxicity, adults, fecundity, insecticides, instars, laboratory experimentation, life tables, longevity, nymphs, oviposition, pests, pyrethrins, sublethal effects, survival rate, toxicity testing, wheat
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 LC10, LC20, and LC25 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. LC20 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 LC25. 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 LC10 and LC20, as well as the net reproductive rate (R0) reduced at LC10 and LC25, while mean generation time (T) increased at LC20. 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 R0, and delayed the development of some stages and increased T.