Sublethal Effects of Bifenazate on Biological Traits and Enzymatic properties in the Panonychus citri (Acari: Tetranychidae)

Abstract

Panonychus citri, is a major citrus pest with a global distribution. But in Pest Management, the extensive use of insecticides has resulted in insecticide tolerance. Bifenazate, a novel acaricides with high biological activity against red mites, such as the T.urticae, P. citri. However, its sublethal effects on P. citri have not been reported. Therefore, in present study, P. citri exposed to sublethal concentration of bifenazate shows high biological activity, and causes great changes of population parameters and enzymatic activity. Life table technology was used to demonstrate sublethal effects on the growth and reproduction of P. citri. The results showed that the developmental duration of immature stage used sublethal concentration of bifenazate (LC10, LC30) were no difference than control. Nevertheless, compared with control group, the female adult duration, the fecundity and longevity were significantly decrease, but the pre-oviposition period was longer; In addition, the net reproductive rate (R0), the mean generation(T) were significantly decreased compared to those of the control, but the intrinsic rate of increase(r), the finite rate(λ) were decreased in LC30 group, however, the doubling time was increased with the increasing concentrations of bifenazate. Furthermore, Enzymatic tests showed that CAT, POD, and CarE activities were higher in LC10 and LC30 treatments than control. The SOD and GST activities were lower in LC30 treatment than control and LC10 treatment. Moreover, the CYP450 activity was decreased with the increasing concentrations of bifenazate. Based on these results, the sublethal concentration of bifenazate may have adverse effects on population growth of P. citri. This result provides certain significant guidance for the Pest Management. As well as that, further studies should be done to explore resistance mechanisms of P. citri exposure to a sublethal concentrations of bifenazate.