水稻及茭白二化螟不同龄期幼虫耐寒性比较

Comparison of cold tolerance of different instars of Chilo suppressalis in Zizania aquatica and rice

为明确水稻及茭白二化螟种群之间在低温环境下的生理生化差异,将室内饲养获得的1~6龄二化螟幼虫分别置在28、0、-3、-6、-9、-12、-15、-18、-21℃条件下处理24 h,再采用分光光度法测定存活幼虫的超氧化物歧化酶、过氧化物酶及过氧化氢酶活性,并利用隶属函数法对二化螟幼虫的耐寒性进行综合评价。结果表明,随着温度下降,水稻及茭白二化螟各龄幼虫的存活率均呈下降趋势;相同低温下,高龄幼虫的存活率高于低龄幼虫;水稻二化螟各龄幼虫的存活率普遍高于相同低温下的同龄茭白二化螟幼虫。随着温度的下降,3种抗氧化酶的活性均呈现显著上升趋势,高龄幼虫的抗氧化酶活性均高于低龄幼虫,水稻二化螟各龄幼虫的抗氧化酶活性普遍高于相同低温下的同龄茭白二化螟幼虫。根据水稻及茭白各龄二化螟幼虫抗氧化酶活性的平均隶属度,验证了水稻二化螟幼虫对低温的耐受力高于茭白二化螟幼虫。

The physiological and biochemical differences between populations of Chilo suppressalis in rice and Zizania aquatica under low temperatures were investigated when the lst to 6th instar larvae of laboratory-reared Chilo suppressalis were treated at 28,O,-3,-6,-9,-12,-15,-18,and-21℃ for 24h.The SOD,POD,and CAT of surviving larvae were measured by the spectrophotometric method,and the cold tolerance of C.suppressalis larvae was comprehensively evaluated by the membership function method.The findings revealed that the survival rate of both rice and Z.aquatica C.suppressalis larvae of all instars decreased with the decrease in temperature.The survival rate of young larvae was lower than that of the old larvae at the same temperature,and the survival rate of rice strain larvae of each instar was generally higher than their counterpart of the Z.aquatica strain.The activity of the three antioxidant enzymes increased significantly as the temperature decreased.Under the same low-temperature conditions,the antioxidant enzyme activities in older larvae were higher than in the younger larvae and higher in the rice strain than in the Z.aquatica strain at the same instar.Based on the average membership value of antioxidant enzyme activities in rice and Z.aquatica strain larvae,it was determined that rice C.suppressalis larvae were more resistant to low temperatures than Z.aquatica C.suppressalis larvae.