Toxicity and Affecting factors of Bacillus thuringiensis var. israelensis on Chironomus kiiensis Tok

• 作 者: Chuan-WangCao[1]Li-LiSun[1]Rong-RongWen[1]Xiao-PengLi[1]Hong-QuWu[2]Zhi-YingWang[1]
• 机 构: Department of Forest Protection,Northeast Forestry University,Harbin 150040,China
• 出 处: 第十届中国林业青年学术论坛
• 发表日期: 2012年期

　　Bacillus thuringiensis var.israelensis (Bti) is a suitable agent for controlling Chironomus kiiensis,a major pest of polluted water.In this study,laboratory bioassays were used to study toxicity and affecting factors of Bti on C.kiiensis larvae.Tests were conducted using three commercial Bti formulations (oil miscible suspension (OF),1,200 ITU/ml; wettable power (WP),1,200 ITU/mg); technical material (TC,5,000 ITU/mg) of Bti.The toxicity of Bti formulations to 3rd and 4th instar C.kiiensis larvae was in decreasing order of TC > OF > WP,based on the 12 h and 24 h LC50 values.Increasing larval densities (from 10 to 30 per bioassay cup) increased the LC50 values for 4th instar C.kiiensis larvae.The LC50 values (4th instar larvae) reared in sand substrate were higher than those from soil substrate,and autoclaved substrates significantly increased the LC50 values.The TC of Bti at 12 and 24 h responded similarly to changes in temperature between 30oC and 15oC,but the LC50 values at a range of tested temperatures showed distinct differences in time points.