Abstract:

The study explored the toxicity of 4 botanical insecticides to the invasive pest Phenacoccus solenopsis, and evaluated their safety to the eggs and adults of Propylaea japonica, aiming to provide ideal agents and a theoretical basis for the green control of Phenacoccus solenopsis. The toxicity of the 4 botanical insecticides to the 3rd instar larvae of Phenacoccus solenopsis and the eggs hatching rate of Propylaea japonica was determined by spray method. The toxicity of 2 kinds of highly effective botanical insecticides against adults of Propylaea japonica was tested by the filter paper contact method. The result showed that the toxicity of the 4 botanical insecticides to the 3rd instar larvae of Phenacoccus solenopsis treated for 24 hours was as follows, matrine1.3% AS (LC₅₀ 81.2831 mg/L) > veratrine 0.5% SL (LC₅₀ 112.8811 mg/L) > rotenone 2.5% EC (LC₅₀ 208.9296 mg/L) > cineole 5% SL (LC₅₀ 343.0920 mg/L). Compared with the chemical control agent of 22.4% spirochete ethyl ester EC, the relative toxicity index was matrine1.3% AS(3.3025) > veratrine 0.5% SL (2.3780) > rotenone 2.5% EC (1.2048) > cineole 5% SL (0.7824). There was no significant difference of hatching rate between the maximum recommended dose of the insecticides in field and the LC₅₀ dose to Phenacoccus solenopsis. The LC₅₀ of matrine AS and veratrine SL to the adults of Propylaea japonica was higher than that to Phenacoccus solenopsis. Combining the benefit toxicity ratio with safety factor, the two insecticides were safe for eggs and adults of ladybug. The experiment screened out matrine 1.3% AS and veratrine 0.5% SL, which had high toxicity to Phenacoccus solenopsis and low ecological risk against Propylaea japonica, so the two insecticides are recommended as ideal agents to control Phenacoccus solenopsis.

Key words: botanical insecticides, Phenacoccus solenopsis, Propylaea japonica, toxicity, safety evaluation