A Rapid Method for Determining Insecticide-resistance of Empoasca flavescens (Homoptera: cicadellidae)

Empoasca flavescens is characterized by its easily hidden tiny body, fast moving and escaping ability, as well as fragile nymphs. Those properties make the entrapment or collection and the separation or handling for testing rather difficult, and hence, are detrimental in experimenting with the live insects. To overcome the hindrances, this study firstly collected the tea shoots infested with E. flavescens from the plantation to keep them on a water medium and raise the insects artificially in the lab. Then, a modified dust sampling device was used to suck the insects at varied air flow rates into the centrifuge tubes containing fresh tea leaves. Finally, the toxicity measurement of LC₅₀ on the insects was determined by pretreating the tubes with varied concentrations of bifenthrin. The data generated verified the applicability of the methodology. The population density of hatched larva obtained from the lab setting was 3.181 head/shoot after 7 days incubation, while it was 1.538 head/shoot in the field. The substantially higher density significantly facilitated the sample collection for the experimentation. And, at a 10 L/min sampling air flow, the insects were harvested rapidly and easily with a 100% survival rate that considerably reduced the workload on or virtually eliminated the need for insect separation. Moreover, the LC₅₀ of bifenthrin on E. flavescens was effectively determined to be 163.55 mg·L^-1. Therefore, it was concluded that the newly developed methodology was rapid, convenient, effective and valid for the determination of the insecticide-resistance of E. flavescens in China.