苏云金芽孢杆菌以色列亚种对花翅摇蚊作用特性研究

A STUDY ON FUNCTIONAL CHARACTERS OF BACILLUS THURINGIENSIS SUBSP. ISRAELENSIS TO CHIRONOMUS KIIENSIS TOKUNAGA

为探索对深圳水源红虫污染进行微生物防治的可行性 ,首次用Bacillusthuringiensissubsp .israelensis,简称Bti (苏云金芽孢杆菌以色列亚种 )对花翅摇蚊 (Chironomuskiiensistokunaga)的作用特性进行研究。生物测定表明 ,BtiIPS82和 1 87对花翅摇蚊 3龄幼虫的LC50 ( 2 4h)分别为 2 4 2和 32 6mg L。对标准菌株IPS82进行的发酵研究表明 ,发酵过程中的菌体密度、芽孢形成和溶解氧变化、对花翅摇蚊的毒力之间具有密切联系。IPS82发酵液应用的环境因素中 ,日光照的影响最大 ,可使其毒力半衰期从 2 1d缩短至 1 0d ;环境温度在 1 5℃～ 30℃内变化 ,Bti使蚊幼虫的致死率都保持在 5 0 %左右。当环境温度 35℃时 ,Bti使蚊幼虫的致死率再提高 1 6% ;环境pH偏离 7～ 1 1时 ,IPS82的毒力从 66 7%下降至40 %左右 ,环境pH3时其毒力下降至 1 6% ;在一定的幼虫密度 (低于 30条 1 0 0mL)范围内IPS82发酵液的毒力稳定 ,但幼虫密度高于 30条 1 0 0mL时毒力呈下降趋势。本研究结果表明 :在一定条件下 ,Bti对花翅摇蚊防治具有良好的应用潜力。

Aimed at feasibility of microbiological control of Chironomidae larvae in sourcewater, Shenzhen, China, the functional characters of Bacillus thuringiensis subsp. Iaraelensis to Chironomus kiiensis tokunaga were studied for the first time. In this study, bioassays were carried out with third-instar larvae, results showed that the LC 50 s(24h) were 24.2 and 32.6 mg/L for Bacillus thuringiensis subsp. Iaraelensis IPS82 and 187 respectively. Tests in fermentation of IPS82 show good correlations between toxicity, cell density, dissolved oxygen and spore-forming phase. The tests on environmental factors influencing toxicity to Chironomus kiiensis tokunaga showed that sunlight is the most important factor, shortening the half life of Bti from 21 days in dark to 10 days; temperature variations(15～30℃) caused no impact on toxicity, but 35℃ increases 16% of larvae mortality. The toxicity of IPS82 is relatively insensitive to change pH deviated from 7 to 11, due to drop of larvae mortality from 66.7 to 40%, at pH of 3, to 16%; its toxicity is stable in low larva density (<30 larvae/100mL), but over the density, the higher the host density, the greater the dose required . The study indicated the feasibility of using Bti to control Chironomus kiiensis tokunaga.