Susceptibility of Spodoptera frugiperda and S. exigua to Bacillus thuringiensis Vip3Aa insecticidal protein

详细信息	查看全文 | 推荐本文 |

• 作者：Maissa Chakroun^a ; Yolanda Bel^a ; Silvia Caccia^a ; Lobna Abdelkefi-Mesrati^b ; Baltasar Escriche^a ; Juan Ferré ; ^a ; ^{juan.ferre@uv.es}
• 关键词：Bioinsecticides ; Mode of action ; Insect proteases ; Insect pest control ; Vegetative insecticidal proteins
• 刊名：Journal of Invertebrate Pathology
• 出版年：2012
• 期刊代码：120_00222011
• 类别：abs
• 出版时间：July, 2012
• 卷：110
• 期：3
• 页码：334-339
• 文件大小：391 K

摘要

The Vip3Aa protein is an insecticidal protein secreted by Bacillus thuringiensis during the vegetative stage of growth. The activity of this protein has been tested after different steps/protocols of purification using Spodoptera frugiperda as a control insect. The results showed that the Vip3Aa protoxin was stable and retained full toxicity after being subjected to common biochemical steps used in protein purification. Bioassays with the protoxin in S. frugiperda and S. exigua showed pronounced differences in LC₅₀ values when mortality was measured at 7 vs. 10 d. At 7 d most live larvae were arrested in their development. LC₅₀ values of 鈥渇unctional mortality鈥?(dead larvae plus larvae remaining in the first instar), measured at 7 d, were similar or even lower than the LC₅₀ values of mortality at 10 d. This strong growth inhibition was not observed when testing the trypsin-activated protein (62 kDa) in either species. S. exigua was less susceptible than S. frugiperda to the protoxin form, with LC₅₀ values around 10-fold higher. However, both species were equally susceptible to the trypsin-activated form. Processing of Vip3Aa protoxin to the activated form was faster with S. frugiperda midgut juice than with S. exigua midgut juice. The results strongly suggest that the differences in the rate of activation of the Vip3Aa protoxin between both species are the basis for the differences in susceptibility towards the protoxin form.