草地螟滞育和非滞育幼虫抗寒能力的研究

对草地螟幼虫过冷却点和冰点测定的结果表明,光照、温度、幼虫滞育的深度以及虫体含水量均可以影响草地螟幼虫的抗寒能力。长光照(16 h)条件下发育成的非滞育幼虫过冷却点、冰点均显著低于短光照(10 h)发育而成的滞育幼虫;无论是非滞育幼虫还是滞育幼虫,经低温处理后抗寒能力都会上升。经4℃处理1 d的非滞育幼虫冰点为-2.28℃,而处理25 d的则降低到-4.76℃,过冷却点可从-13.97℃降低到-21.47℃;经4℃处理25、35 d的滞育幼虫,其过冷却点分别为-25.82、-26.79℃,冰点分别为-5.59-、9.13℃。滞育幼虫的过冷却点、冰点与其体重不相关,但与其体内的含水量显著相关。

Cold-hardiness in the diapause and non-diapause larvae of meadow moth,Loxostege sticticalis L.

The cold-hardiness of larval meadow moths,Loxostege sticticalis L.reared at different photoperiods,treated by various duration of low temperature and at different diapause states was investigated under laboratory conditions.The super-cooling points(SCP) and freezing point(FP) of the larvae reared at the photoperiod of L16∶D8 was significantly greater than those reared at L10∶D14,suggesting that photoperiodism is critical to the cold-hardness of meadow moth.Larvae obtained by long and short photoperiodism herein were named as diapause and non-diapause larvae,respectively.Previous treatment of larvae(diapause or non-diapause) by low temperature(4℃),could greatly increase their capacity in cold-hardness.Developmental stages of the diapause larvae also influenced their cold-hardness.The FP of non-diapanse larval was-2.28 ℃ after one day,but it reduced to-4.76 ℃ after 25 days.The SCP of non-diapause larval were from-13.97 ℃ to-21.47 ℃.For the diapause the SCP and FP were from-25.82 ℃ and-5.59 ℃ to-26.79 ℃ and-9.13 ℃ after 25 days and 35 days,respectively.Studies on the relations between water contents and body weight of the diapause larvae demonstrated that the SCP and FP were negatively significantly correlated with their water contents but did not show any relations to their size or weight.The significances of these findings in population dynamics of the meadow moth were also discussed.