Resistance of Eriosoma lanigerum to three insecticides in different areas.

Objectives] To assess the resistance of Eriosoma lanigerum to different kinds of insecticides, and provide a theoretical basis for selecting insecticides to control of this pest in the field. [Methods] The resistance of E. lanigerum to avermectin, cypermethrin and imidacloprid in 14 regions of 3 provinces was determined using the glass tube membrane method from June to July 2018. [Results] The lowest LC50 value to avermectin, 6.813 mg/L, was recorded in Yangling, Xi'an, and the highest, 79.496 mg/L, was recorded in Zhaoyuan, Yantai. Resistance to cypermethrin was low in most areas; the Longkou area in Yantai had the lowest resistance (LC50 = 4.341 mg/L) and the Qixia area, also in Yantai, had the highest (LC50 = 37.689 mg/L). Resistance to imidacloprid was lowest in the Jimo area of Qingdao (LC50 = 5.261 mg/L), and moderate in the Zhaoyuan area of Yantai with an RR of 10.859 and an LC50 value of 57.128 mg/L. The results of insecticide resistance tests show that resistance of third instar nymphs was similar to that of adult aphids, except that nymphs in the Penglai area of Yantai had increased resistance to avermectin and imidacloprid. [Conclusion] Resistance of E. lanigerum to commonly used insecticides remains low in most areas of northern China. Alternating between different pesticides should be continued to prevent and delay the development of resistance in this pest. [ABSTRACT FROM AUTHOR]