Risk assessment of broflanilide resistance in Panonychus citri (McGregor): Cross-resistance, inheritance and relative fitness

Abstract

Panonychus citri (McGregor) is an important economic pest in the orange orchard of the world, which has developed varying degrees of resistance to many acaricides. Broflanilide is a novel γ-aminobutyric acid (GABA) receptor allosteric modulator with high insecticidal activity against a broad spectrum of insects. However, the risk of resistance to broflanilide in P. citri has not been studied. In this study, the BR strain selected from susceptible strain of P. citri with broflanilide for 44 generations, developed 32.5-fold resistance to broflanilide, and did not exhibit cross-resistance to fipronil, fluxametamide, abamectin, pyridaben, and cyflumetofen. Broflanilide resistance in the BR strain of P. citri was autosomal, incomplete dominant and polygenic. The duration of larval and deutonymph, total life span and the number of eggs were significantly increased in the BR strain compared to the SS strain. The higher relative fitness (R_f) value (1.289) indicated that there was a fitness advantage in the BR strain. Glutathione S-transferase and esterase activities in the BR strain were significantly increased compared with the SS strain. These findings provide valuable information for developing resistance management strategies to delay broflanilide resistance and maintain sustainable control of P. citri.