Abstract:

【Aim】 Secondary endosymbionts may affect the susceptibility of Bemisia tabaci to insecticides. This study aims to reveal the influence of endosymbiont Cardinium infection on the insecticide tolerance of B. tabaci MED. 【Methods】 The tolerance of Cardinium-infected and uninfected lines with identical genetic background of two populations of B. tabaci MED (Lingshui population from Lingshui, Hainan Province, South China, and Shouguang population from Shouguang, Shandong Province, North China) to different concentrations of two neonicotinoid insecticides (thiamethoxam and imidacloprid) was assayed in the laboratory. 【Results】 After treatment with various concentrations of thiamethoxam and imidacloprid, respectively, the mortalities of the Cardinium-infected line of Lingshui population were significantly lower than those of the uninfected line. After exposure to 100, 150, 175 and 200 mg/L thiamethoxam and 175 and 200 mg/L imidacloprid, respectively, the mortalities of the Cardinium-infected line of Shouguang population were significantly higher than those of the uninfected line. Compared with the uninfected line, the resistance ratios of the Cardinium-infected line of Lingshui population under the pressure of thiamethoxam and imidacloprid were 1.355 and 1.847, respectively, while those of Cardinium-infected line of Shouguang population were 0.790 and 0.847, respectively. 【Conclusion】 Endosymbiont Cardinium infection can significantly influence the tolerance of B. tabaci MED to thiamethoxam and imidacloprid, and the influence varies among its different populations. The results provide valuable references for revealing the population adaptability and expansion mechanism of B. tabaci MED.

Key words: Bemisia tabaci, endosymbionts; Cardinium, insecticide tolerance, neonicotinoid insecticides, thiamethoxam, imidacloprid