Biology of Gastrolina depressa in Harbin and toxicity assay of three chemicals
Gastrolina depressa has caused significant damage to Juglans mandshurica plantations in Harbin.To ef-fectively control this pest,the biological characteristics of G.depressa in Harbin were observed,and the toxicity of cypermethrin,avermectin and imidacloprid to the adult of G.depressa was determined.The results showed that G.depressa exhibited a single generation per year in Harbin with larvae hatching from mid-May to mid-June.The pu-pae and adults were first observed in early June.The female-to-male ratio of G.depressa was 1∶1 with mating oc-curring between 11 am to 3 pm peaking at approximately 2 pm,followed by spawning from 2 pm to 5 pm reaching its peak at 3 pm.Among the tested pesticides,cypermethrin demonstrated the highest toxicity towards G.depressa,followed by avermectin and imidacloprid.Based on these results,it is recommended that avermectin be prioritized for pest control purposes,while cypermethrin should only be used as an emergency measure.