Resistance monitoring of the field populations of Laodelphax striatellus (Hemiptera: Delphacidae) to twelve insecticides in Henan Province of China

In order to clarify the insecticide resistance status in the field populations of the small brown planthopper (Laodelphax striatellus (Fallén)) from Henan Province, the resistances to 12 commonly used insecticides in seven field populations of L. striatellus collected from Xinxiang, Puyang, Kaifeng, Zhumadian, and Xinyang in Henan Province of China during 2020 to 2021 were detected by rice seedling dipping method. The results showed that the field populations of L. striatellus have developed medium-level resistance to buprofezin (resistance ratio, RR=14.9-91.1). Furthermore, the field populations produced low to medium-level resistance to pymetrozine (RR=6.91-16.7) and chlorpyrifos (RR=8.48-70.0) and were susceptible to medium-level resistance to triazophos (RR=1.29-11.1). In addition, all field populations of L. striatellus were susceptible or low-level resistance to thiamethoxam (RR=0.95-5.19) and lambda-cyhalothrin (RR=3.31-7.24), and relatively susceptible to imidacloprid (RR=0.89-3.92), acetamiprid (RR=1.11-2.33), nitenpyram (RR=0.16-0.64), dinotefuran (RR=1.87-3.86), isoprocarb (RR=0.47-1.37) and flonicamid (RR=1.63-4.33), respectively. The results shed light on the sustainable control of L. striatellus field population and scientific use of insecticides in Henan Province.