Sublethal effects of the novel cis-nitromethylene neonicotinoid cycloxaprid on the cotton aphid Aphis gossypii Glover (Hemiptera: Aphididae)

Abstract

Cycloxaprid is a novel cis-configuration neonicotinoid insecticide that is effective against a wide range of insect pests, including those that are resistant to conventional neonicotinoids. In this study, life table parameters were applied to estimate the cycloxaprid-induced sublethal effects on Aphis gossypii. The results indicated that the LC₂₀ (0.81 mg a.i. L^-1) of cycloxaprid significantly decreased the pre-oviposition period in first-progeny adults. Additionally, the life expectancy of F1 generation adults was reduced. However, no significant differences were observed for the intrinsic rate of increase (r _i ), finite rate of increase (λ), net reproductive rate (R₀), or mean generation time (T) of F1 individuals. Therefore, resurgence in the A. gossypii population induced by a low concentration of cycloxaprid might not occur. Additionally, the response of the detoxification enzymes showed that cycloxaprid at the LC₂₀ inhibited cytochrome P450 monooxygenase (P450) and glutathione S-transferase (GST) activities at 6 h after exposure. Such inhibition of P450 and GST activities could lead to a decrease in the metabolism of cycloxaprid, which would increase the efficacy of cycloxaprid. Therefore, our results contribute to the assessment of the overall effects of cycloxaprid on A. gossypii.

Figure 1

Age-stage survival rate (s_xj) of the F1-generation A. gossypii.

Figure 2

Age-specific survival rate (l_x), age-specific fecundity (m_x), l_xm_x and age-specific reproductive value (v_x) of the F1-generation A. gossypii.

Figure 3

Age-stage life expectancy (e_xj) and age-specific life expectancy (e_x) for the F1-generation A. gossypii.

Figure 4

The activity of P450, CarE, GST and AChE of A. gossypii treated with the LC₂₀ of cycloxaprid. The results are presented as mean ± SE. The same letters above the bars indicate no significant difference at P < 0.05.