辣椒碱对烟粉虱的生物活性及生长发育和生殖力的影响

在实验室条件下研究了辣椒碱对烟粉虱的生物活性及生长发育和生殖力的影响.结果表明:辣椒碱对烟粉虱各虫态均有杀虫活性,且随辣椒碱浓度的增大活性增强；辣椒碱浸叶法/浸虫法处理对烟粉虱成虫、卵和若虫的毒力(LC50分别为3525.79、1603.29和1526.27mg·L-1))均高于内吸法处理(LC50分别为5360.04、2359.19和5897.43 mg.L-1),两种处理方法下辣椒碱对烟粉虱卵的毒力均明显高于对成虫的毒力；2000和4000 mg·L-1浓度辣椒碱对烟粉虱成虫具有明显的拒食作用,烟粉虱在该两种浓度辣椒碱处理过的棉花叶上取食24 h的蜜露分泌量均显著低于取食非处理棉花叶后的蜜露分泌量；辣椒碱各试验浓度对烟粉虱成虫均表现出较强的产卵忌避作用,当辣椒碱处理浓度达4000 mg·L-1时,对烟粉虱的选择性产卵忌避率和非选择性产卵忌避率分别高达94.2％和83.0％.500、1000和2000 mg·L-1辣椒碱浸渍处理对烟粉虱存活卵和若虫的发育历期、成虫羽化率均没有影响,但辣椒碱4000mg·L-1处理明显延长烟粉虱若虫发育历期、降低成虫羽化率.不同浓度辣椒碱处理均明显抑制烟粉虱生殖力,且这种抑制作用随辣椒碱浓度的增大而增强.

Biological activity of capsaicin and its effects on development and fecundity in Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae)

Biological activity of capsaicin and its effects on development and fecundity in Bemisia tabaci were tested in the laboratory. The results showed that capsaicin induced direct mortality in different developmental stages of B. tabaci, and the mortality of whiteflies were significantly dosage-dependent. The toxicity of capsaicin to different developmental stages of B. tabaci by either leaf-dip or egg/larval-dip bioassays (the LC50 for adult, egg and nymph were 3525.79, 1603.29 and 1526.27 mg x L(-1), respectively) was higher than that by systemic bioassay (the LC50 for adult, egg and nymph were 5360.04, 2359.19 and 5897.43 mg x L(-1), respectively), and toxicity of capsaicin to eggs was higher than to adults in both bioassay methods. 2000 and 4000 mg x L(-1) concentrations of capsaicin had strong antifeedant effect on B. tabaci, as exemplified by reduced honeydew excretion of adults feeding on leaves treated with capsaicin compared with untreated leaf discs. Capsaicin also had strong oviposition deterrence against B. tabaci, with 94. 2% of selective oviposition deterrence rate and 83. 0% of nonselective oviposition deterrence rate when exposed to 4000 mg x L(-1) concentration for 24 h. We did not find effect on development time of B. tabaci eggs and nymphs, and on molting rate of adults when exposed to capsaicin at 500, 1000 and 2000 mg x L(-1) concentrations, however, exposure to 4000 mg x L(-1) concentration of capsaicin significantly affected development time of B. tabaci nymphs and molting rate of adults. Exposure to capsaicin also significantly reduced fecundity of B. tabaci adults, and this reduction was significantly dosage-dependent.