Breaking the beetle barrier: Innovative strategies for controlling Hylurgus ligniperda in China

Hylurgus ligniperda is a major quarantine pest of forest trees in China. Exploring emergency control techniques in the field can effectively avoid large outbreaks and the spread of H. ligniperda. In this study, H. ligniperda larvae were found to be more tolerant to the tested insecticides than the adults were. Deltamethrin, β-cypermethrin, imidacloprid and malathion exhibited significant toxicity to adult beetles. Insecticides in emulsifiable concentrates (ECs) have been applied in semifield research to combat adult beetles. After treatment with 1000 mg L^-1 deltamethrin, the mortality rate of the adult beetles reached 100 % on the 7th day. Deltamethrin had the highest residual efficacy and the longest insecticidal duration, and adult mortality reached 23.33 % after 30 days. Furthermore, the activities of detoxification and protective enzymes in adult beetles exposed to pyrethroid insecticides significantly changed and may be responsible for their rapid death. To avoid the development of drug resistance caused by the single application of deltamethrin and to conduct emergency control of this beetle during the rainy season, semifield research was carried out using four granular (GR) insecticides with water treatment. The results revealed that the adult mortality rate reached 100 % after 11 and 13 days of treatment with phoxim (with water addition) and dinotefuran (no water added), respectively, with effects persisting for 30 and 18 days, respectively. Moreover, no drug resistance was observed during the short-term control of H. ligniperda. During peak beetle outbreaks, 1000 mg L^-1 deltamethrin (EC) can be applied every 30 days. After the peak, dinotefuran (GR) can be applied every 18 days during the non-rainy season, while phoxim (GR) can be applied every 30 days during the rainy season.