草地贪夜蛾耐低温能力研究

Study on the cold resistance of the fall armyworm,Spodoptera frugiperda

为阐明草地贪夜蛾的抗寒能力及越冬虫态,为其越冬区划和监测预警提供科学依据,本研究测定了草地贪夜蛾不同发育阶段在4种低温(-10℃、-5℃、0℃和5℃)条件下的存活率,并通过计算机软件拟合死亡率回归方程,计算出LT 50、LT 90和LT 99。结果表明:草地贪夜蛾在4种低温条件下处理2 h后各虫态存活率均随处理温度降低而显著下降(P<0.05)。在-10℃下,除蛹外,其他各虫态的存活率均小于60%,其中成虫存活率最低,仅为40.34%。在-10℃及-5℃处理温度下,蛹的存活率显著高于其他虫态(P<0.05)。对死亡率回归方程分析表明,草地贪夜蛾同一虫态的LT 50、LT 90及LT 99均表现为5℃>0℃>-5℃>-10℃。在相同温度条件下,草地贪夜蛾的存活能力随着发育阶段的变化而变化,不同虫态的耐低温能力依次为卵<成虫<幼虫<蛹。在所有测试温度中,经9 d后卵的孵化率最高为1.8%。综上,草地贪夜蛾蛹耐低温能力最强,是草地贪夜蛾最有可能越冬的虫态。在0℃条件下,蛹的LT 99为40.27 d,表明其在冬季温度低于0℃的时间连续超过40 d的地区不能越冬。这些结果为科学划分我国草地贪夜蛾越冬区划及监测预警提供了依据。

To further clarify the cold-resistance and possible overwintering stage of Spodoptera frugiperda,the survival rates of S.frugiperda at different developmental stages under four different low temperatures were measured and the LT 50,LT 90 and LT 99 were calculated.The results showed that the survival rates of S.frugiperda under different low temperatures decreased significantly with decrease of the temperature.At-10℃,except for pupae,the survival rates of other stages were less than 60%,and the survival rate of adults was only 40.34%.The survival rate of pupae was significantly higher than that of other stages at-10℃and-5℃.According to the mortality regression equation,the LT 50,LT 90,and LT 99 of same developmental stage showed a tendency of 5℃>0℃>-5℃>-10℃.Under the same temperature conditions,the viability of S.frugiperda varies with the developmental stage.The low temperature tolerance of different developmental stages from weak to strong was egg<adults<larva<pupa.Among all tested temperatures,the hatching rate of eggs after nine days is the highest 1.8%.These results showed that the pupa was the most likely overwintering stage of S.frugiperda.The LT 99 of pupae was 40.27 d at 0℃,which indicated that it cannot overwinter in areas where the temperature is continuously lower than 0℃for more than 40 d.These results provided a basis for the scientific overwintering division of S.frugiperda,monitoring and early warning in China.