高温对粘虫未成熟期生长发育的影响

本文报道了粘虫卵、幼虫和蛹在２４℃以上４种高温中生长发育的情况。结果表明，卵在相对湿度８０％左右，温度为２４－３３℃范围内均能顺利孵化，孵化率均在８７％以上，而３５℃中卵不能孵化，幼虫和蛹死亡率随着温度的升高而增加，３５℃时所有幼虫均在幼虫期或蛹期死亡，未成熟期（卵、幼虫和蛹）在２４－３０℃范围内随着温度的升高而缩短，３３℃时反而有所延长。高温对幼虫虫龄及各龄幼虫头壳宽度也有显著的影响（ｐ＜０．０５）．２４、２７℃中老熟幼虫均为６龄，而３０、３３、３５℃中７龄老熟幼虫比例分别占４％、２４％、１００％．各龄幼虫的头壳宽度以２７℃的最宽，且随着温度的升高而逐渐下降（３５℃的２龄幼虫除外），不论其差异是否显著。３３℃以上高温显著不利于幼虫头壳的增长。蛹也是以２７℃的最重，且随着温度的升高而降低，３３℃时达到显著差异（ｐ＜０．０５）．由此可见，３３℃以上高温不仅不利于粘虫幼虫和蛹的生存，而且导致幼虫蜕皮次数增加，各龄幼虫头壳宽度变小，未成熟期延长及蛹重降低等发育受阻现象，而３５℃高温直接对卵和蛹有完全致死作用，这些结果均是粘虫夏天在我国南方地区不能渡夏的直接原因。

Effects of High Temperature on the ImmatureStages of The Oriental ArmywormMythimna SeparataWalker

The oriental armyworm , M ythimna separata ( Walker ) was reared at five constant temperatures from24 ℃ to 35℃. The eggs hatched well at all temperatures except 35 ℃. Develop- ment was completed at temperatures from 24 ℃ to 33 ℃ , but at 35 ℃ , none survived beyond the pupae. The duration of immature stages decreased with rise in temperature . up to 30 ℃ , but a further rise bought of each larvae were affeeted significantly by temperature , From24 ℃ to 27 ℃, there were six larval stadia , but at 30 ℃ and 33 ℃ , approximately 4 and 24 percent of the larvae required a seventh stadium to complete development respectively. For larvae with six instars , the mean head width in the last instar ranged from 3. 6 2mm at 24 ℃, to 3. 52 mm at 33 ℃ , the widthest occurred at 27℃ , the narrowest occurred at 33℃ , at 35 ℃ all survived larvae required an additional moult tocomplete development. The pupal weight affecedsignificently also decreased with rise in temperature up to 33℃. Results obtained from this suggest the oriental armyworm has lower hatching rate , lower larvae and pupae survival , longer duration of immature stage and light pupal weight at high temperature were the derect reasons why it has no ability to over the summer in chinese south aera in annual summer.