Abstract: 【Aim】 To ascertain the toxicity levels and field control efficacy of bioinsecticides and neonicotinoid insecticides against Amrasca biguttula nymphs, so as to provide a scientific basis for its control. 【Methods】 The median lethal concentration (LC₅₀) values of three bioinsecticides (veratramine, avermectin and matrine), and five neonicotinoid insecticides (nitenpyram, imidaclothiz, dinotefuran, thiamethoxam and acetamiprid) against the 3rd instar nymphs of A. biguttula in North Hunan cotton area were determined at 24 h after treatment using leaf-dipping method in laboratory. Based on the recommended field application rate of each insecticide, the field control efficacy of 0.5% veratramine soluble concentrate (SL) (5.625 g a.i./hm²), 5% avermectin emulsifiable concentrate (EC)(10.5 g a.i./hm²), 2% matrine aqueous solution (AS) (10.5 g a.i./hm²), 10% nitenpyram AS (30 g a.i./hm²), 40% imidaclothiz water dispersible granule (WG) (30 g a.i./hm²), 20% dinotefuran suspension concentrate (SC) (75 g a.i./hm²), 30% thiamethoxam SC (33.75 g a.i./hm²) and 5% acetamiprid EC (18 g a.i./hm²)  against A. biguttula was evaluated by using artificial spraying in Taoyuan County, Hunan during the occurrence peak of A. biguttula in August, 2021. 【Results】 The laboratory toxicity assessment result revealed that at 24 h after treatment, the toxicity of the eight insecticides to A. biguttula nymphs was ranked in a descending order as follows: 0.5% veratramine SL>5% avermectin ES>10% nitenpyram AS>40% imidaclothiz WG>20% dinotefuran SC>2% matrine AS>30% thiamethoxam SC>5% acetamiprid EC. The bioinsecticides 0.5% veratramine SC and 5% avermectin EC had the LC₅₀ values of 1.79 and 4.00 mg/L against the 3rd instar nymphs of A. biguttula, respectively, exhibiting higher toxicity than the five tested neonicotinoid insecticides. Field control efficacy experiment results showed that 0.5% veratramine SL had the best field control efficacy against A. biguttula， with the corrected control efficacy of 91.36% at 1 d after application, significanly higher than that of the other insecticides. At 7 and 14 d after application, the field corrected control efficacy of 0.5% veratramine SL against A. biguttula was 86.14% and 80.09%, respectively, only lower than that of 20% dinotefuran SC (92.02% and 86.99%, respectively), showing no significant difference from that of 10% nitenpyram AS and 40% imidaclothiz WG, and significantly higher than that of the other insecticides. 【Conclusion】 These results suggest that veratramine and nitenpyram show good indoor insecticidal activities and field control efficacy against A. biguttula populations in North Hunan cotton area. To reduce the improper use of insecticides and promote the synergistic application of chemical and biopesticides, we recommend that veratramine and nitenpyram should be used alternately to control A. biguttula in cotton fields.

Key words:  Amrasca biguttula, bioinsecticide, neonicotinoid insecticides, laboratory toxicity, field control efficacy