Inhibitory effects of alkaloids from Sophora alopecuroids on feeding, development and reproduction of Clostera anastomosis

Abstract

Alkaloids from Sophora alopecuroids were bioassayed with Clostera anastomosis for their antifeedant and growth inhibitory effects. The antifeedant rate in choice test reached 62% 86% at the dose 2.5 mg/mL, while in non-choice bioassay the rate was only 20% 29%. In choice bioassay, the antifeedant rate increased with larval instars of C. anastomosis and did not in non-choice experiment. The alkaloids also imposed a strong influence on the growth of C. anastomosis larvae, i.e., after feeding on the leaves treated with alkaloid, the larvae lost their weight, weight gain, and relative growth rate (RGR) significantly when compared with the controls. In the second day after treatment with the dose at 10 mg/mL of the alkaloid, the RGR reduced by 39.8%, and the food intake and the feces weight were respectively 57.7% and 57.4% of the controls. The approximate digestibility (AD) increased significantly, and the efficiency in converting digested food (ECD), and the efficiency in converting ingested food (ECI) decreased greatly after feeding the treated leaves. Moreover, the eggs laid per female were also inhibited by this alkaloid. The significance and prospect of the alkaloids in controlling forest insect pests were also discussed.