Comparative toxicity of abamectin and Bifenazate against the predatory mite, Euseius amissibilis and its prey...

Euseius amissibilis is a highly prevalent predator in citrus orchards. This study assessed the direct and residual toxicity of abamectin and bifenazate on adult male and female of E. amissibilis and its prey Tetranychus urticae. Additionally, we assessed the sublethal effects of abamectin on the biological and reproductive parameters of the predator. The results showed that both the predator and pest mite were more susceptible in the direct method than the residual method. The LC₅₀ values of bifenazate for T. urticae females were 4.13 and 5.89 mg active ingredient (a.i.)/L in the two methods, respectively. The LC₅₀ values for abamectin were found to be 0.064 and 0.074 mg a.i./L, respectively. The bioassay results demonstrated that bifenazate is safe for E. amissibilis, while abamectin was found to be toxic to the predatory mite; the lethal concentrations (LC₅₀) of abamectin for females were 4.51 mg a.i./L in the direct method and 24.78 mg a.i./L in the residual method. The comparative toxicity assays also confirmed the safety of bifenazate. The sublethal tests showed that abamectin negatively affected the oviposition period, fecundity, and longevity of E. amissibilis females. The findings indicate that bifenazate could be an effective choice for integrated management programs targeting T. urticae, especially when the primary natural enemy is E. amissibilis. Additionally, using abamectin may pose serious challenges for these programs.