感染杨干象幼虫的高致病力虫生真菌菌株筛选

【目的】筛选对杨干象幼虫具有高致病力的真菌菌株,测定防治效果,为生物防治提供依据。【方法】选用7株虫生真菌菌株对杨干象幼虫进行室内致病力测定,筛选出高致病力菌株并进行林间生防试验,对受侵染的杨干象幼虫的致病症状进行研究。【结果】1)用菌株CFCC87323以108conidia·m L-1分生孢子悬浮液处理杨干象幼虫,校正死亡率达93.38%,致死中时LT50为3.536天,致死中浓度LC50为7.0×103conidia·m L-1;林间生防试验采用108conidia·m L-1孢子悬浮液涂干法,校正死亡率达77.62%。2)用菌株ACCC30830以108conidia·m L-1孢子悬浮液处理杨干象幼虫,校正死亡率达81.46%,致死中时LT50为4.248天,致死中浓度LC50为5.43×103conidia·m L-1;林间生防试验采用108conidia·m L-1孢子悬浮液涂干法,校正死亡率达66.06%。3)用菌株ACCC30831以108conidia·m L-1孢子悬浮液进行室内生物测定,校正死亡率达73.51%;林间防治试验采用108conidia·m L-1孢子悬浮液涂干法,校正死亡率达58.48%。4)用菌株CFCC87327以108conidia·m L-1孢子悬浮液进行室内生物测定,校正死亡率达72.85%;林间防治试验采用108conidia·m L-1孢子悬浮液涂干法,校正死亡率达56.32%。5)观察杨干象幼虫感染的致病症状发现,杨干象幼虫被菌株CFCC87323侵染后,从出现明显症状到死亡变成僵虫需要(74.67±2.31)h,到虫体布满菌丝需要(93.67±3.21)h。【结论】白僵菌菌株CFCC87323对杨干象幼虫致病力最高,菌株ACCC30830次之。菌株ACCC30831和CFCC87327对杨干象幼虫也表现出较好的致病效果。

卡死克杀灭家蝇的试验研究

本文报告卡死克(Cascade)在实验室内杀灭家蝇及现场杀灭家蝇Ⅲ龄幼虫的效果。结果表明,实验室内卡死克对家蝇Ⅲ龄幼虫的LC_(50)为0.0009;0.01%和0.005%卡死克水溶液,对家蝇Ⅱ、Ⅲ龄幼虫有很好的杀灭效果,但灭卵效果较差;用含有0.06%和0.006%卡死克的饵料饲喂后影响家蝇寿命,KT_(50)前者为23.1336天,后者为30.5844天,但经t检验差别不显著,对照组KT_(50)为59.5662天。饲喂含有0.06%和0.006%卡死克饵料的家蝇,产下的卵不能发育成成蝇。现场采用0.013%和0.0067%卡死克水溶液,对野外家蝇Ⅲ龄幼虫具有很好的杀灭效果。

Effects of total dissolved gas supersaturated water on lethality and catalase activity of Chinese sucker(Myxocyprinus asiaticus Bleeker)

Total dissolved gas(TDG) supersaturation caused by dam sluicing can result in gas bubble trauma(GBT) in fish and threaten their survival.In the present study,Chinese suckers(Myxocyprinus asiaticus Bleeker) were exposed to TDG supersaturated water at levels ranging from 120% to 145% for 48 h.The median lethal concentration(LC 50) and the median lethal time(LT 50) were determined to evaluate acute lethal effects on Chinese suckers.The results showed that the LC 50 values of 4,6,8,and 10 h were 142%,137%,135%,and 130%,respectively.The LT 50 values were 3.2,4.7,7.8,9.2,and 43.4 h,respectively,when TDG supersaturated levels were 145%,140%,135%,130%,and 125%.Furthermore,the biological responses in Chinese suckers were studied by assaying the catalase(CAT) activities in gills and muscles at the supersaturation level of 140% within LT 50.The CAT activities in the gills and muscle tissues exhibited a regularity of a decrease after an increase.CAT activities in the muscles were increased significantly at 3/5LT 50(P<0.05) and then came back to the normal level.However,there were no significant differences between the treatment group(TDG level of 140%) and the control group(TDG level of 100%) on CAT activities in the gills before 3/5LT 50(P>0.05),but the activities were significantly lower than the normal level at 4/5LT 50 and LT 50(P<0.05).