Effects of sublethal concentrations of deltamethrin on fitness of white-backed planthopper,Sogatella furcifera (Horváth)

Sogatella furcifera (Horváth) is one of the most important migratory pests of rice in Asia. When normal concentrations of deltamethrin are applied to control lepidopteran pests of rice in the field, it is likely that S. furcifera will be exposed to sublethal concentrations of this chemical. Therefore, we examined the sublethal effects of deltamethrin on the development and reproduction of S. furcifera using the rice stem dipping method. The results showed that exposure of 3rd instar S. furcifera to LC₁₀ and LC₂₅ deltamethrin significantly increased the emergence rates compared with the F₀ generation control group, but there was no significant difference in the nymphal stage duration, adult longevity and female fecundity. Nymphal duration of the F₁ generation was significantly prolonged under both treatments. Female fecundity also increased in this generation, with a significant difference between the LC₂₅ treatment group and controls. The relative fitness of the LC₁₀ and LC₂₅ treatment groups was 0.84 and 0.80, respectively. The results showed that sublethal concentrations of deltamethrin stimulate the reproduction of S. furcifera, but decrease the relative fitness of the population. These results provided a reference point for the application of insecticides to control S. furcifera.