Abstract:

Objective　To study the mechanism of the toxicity of celangulin against Aedes albopictus larvae and its influence on various aspects, such as the growth and development of mosquito larvae. Methods　Conventional biological approaches were employed for determination of the toxicity and the impact on the larva growth and development: the changes in the gastrointestinal morphology were identified by HE staining; the antifeedant activity was measured through the colorimetric determination of chromium oxide. Results　With increasing concentrations, celangulin had strengthening toxicity against the fourth instar larvae of Ae. albopictus, with the LC₅₀ of 22.66 (18.38-27.95) mg/L and LC₉₅ of 84.51 (60.87-142.27) mg/L. Celangulin could reduce the pupation rate and extend the average pupation time and the average eclosion time of Ae. albopictus larvae, though it had no significant effect on the eclose rate. As the concentration of celangulin increased, its antifeedant activity became stronger, leading to gastrointestinal morphological changes: brush border loss and midgut degeneration and disintergration. Conclusion　Celangulin was able to kill Ae. albopictus larvae through gastrointestinal toxicity, antifeedant activity and contact toxicity, and inhibit their growth and development.

Key words: Celangulin, Plant pesticides, Aedes albopictus, Antifeedant activity

摘要：

目的　研究苦皮藤素对白纹伊蚊幼虫的毒杀作用机制及对该蚊幼虫生长发育等各种因素的影响。方法　采用常规生物学法进行毒力测定及观察对蚊幼虫生长发育的影响， HE染色观察胃肠形态的改变，通过氧化铬的比色法测定拒食活性。结果　随苦皮藤素浓度的增大，其对白纹伊蚊4龄幼虫的毒杀作用力增强， LC₅₀为22.66（18.38～27.95）mg/L，LC₉₅为84.51（60.87～142.27）mg/L。苦皮藤素能降低白纹伊蚊幼虫的化蛹率，延长平均化蛹时间和平均羽化时间，但对羽化率的影响不明显。随苦皮藤素作用浓度的增大，拒食活性也增强。胃肠形态发生改变：刷状缘脱落，中肠细胞变性、崩解。结论　苦皮藤素能通过胃毒、拒食、触杀等作用方式毒杀白纹伊蚊幼虫，并能抑制其生长发育。

关键词: 苦皮藤素, 植物杀虫剂, 白纹伊蚊, 拒食活性