Laboratoire d'Ecologie Alpine, UMR 5553 CNRS-Université de Grenoble, Grenoble, France.
Pest Manag Sci. 2011 Jan;67(1):122-8. doi: 10.1002/ps.2046. Epub 2010 Oct 27.
The simultaneous production of six different toxins by Bacillus thuringiensis israelensis (Bti) is thought to delay the evolution of resistance in treated mosquito populations. Recent studies have shown that Bti can persist and proliferate in the environment, thereby imposing continuous selective pressure on mosquito populations, raising concerns about the long-term effectiveness of this bioinsecticide. In order to evaluate the effect of Bti persistence on the evolution of resistance, the authors selected a laboratory Aedes aegypti L. strain with field-collected leaf litter containing Bti toxins.
It is shown that resistance to each individual Bti toxin (up to 30-fold) can be obtained after only a few generations of selection. However, the resistance to commercial Bti and to environmental Bti remains low (twofold and 3.4-fold respectively) in the selected strain. Furthermore, some selected individuals exhibited resistance to Cry4B but not to Cry4A, suggesting that two distinct resistance mechanisms are involved in the resistance to these two toxins.
Considering that resistance to Cry toxins might act as a first step to resistance to a complete Bti toxin mixture, the present results highlight the importance of testing each toxin individually in order accurately to monitor Bti toxin resistance evolution in field populations.
苏云金芽孢杆菌以色列亚种（Bti）同时产生六种不同的毒素，这被认为可以延缓处理蚊群中抗性的进化。最近的研究表明，Bti 可以在环境中持续存在和增殖，从而对蚊群施加持续的选择压力，这引发了人们对这种生物杀虫剂长期有效性的担忧。为了评估 Bti 持久性对抗性进化的影响，作者选择了一个具有田间采集的含 Bti 毒素叶凋落物的实验室埃及伊蚊 L. 品系。
研究表明，在仅经过几代选择后，就能获得对每种 Bti 毒素（高达 30 倍）的抗性。然而，在选择的品系中，对商业 Bti 和环境 Bti 的抗性仍然较低（分别为 2 倍和 3.4 倍）。此外，一些选择的个体对 Cry4B 表现出抗性，但对 Cry4A 没有抗性，这表明两种不同的抗性机制参与了对这两种毒素的抗性。
鉴于 Cry 毒素的抗性可能是对完整 Bti 毒素混合物抗性的第一步，因此本研究结果强调了单独测试每种毒素的重要性，以便准确监测田间种群中 Bti 毒素抗性的进化。
