泰安地区松阿扁叶蜂越冬幼虫抗寒性

松阿扁叶蜂越是松树的重要食叶害虫之一。其幼虫在松林土壤中越冬,越冬幼虫的抗寒能力影响翌年的种群密度和危害程度。用NTC-TD热敏电阻 数字电表法研究了越冬幼虫的过冷却能力并调查了越冬场所、龄期、死亡率等。结果表明:越冬幼虫的过冷却点随外界温度的高低而变化。4、5、6龄越冬幼虫平均过冷却点依次由越冬初期的-19.3℃-、20.3℃-、21.6℃降至越冬期的-22.5℃-、24.8℃-、23.1℃,冰点依次由越冬初期的-12.8℃-、12.9℃-、12.1℃降至越冬期的-14.1℃、-16.8℃-、15.3℃。从越冬期进入早春出蛰期后,随着温度的回升,过冷却点也随之升高。调查林间越冬幼虫龄期表明,4龄、5龄、6龄皆有,以5龄为最多,占53%;越冬幼虫以山坡中部和顶部土壤瘠薄处虫口密度较小,分别占28.6%和29.3%,山坡基部土层较厚处密度较大,占42.1%;越冬幼虫在树冠内的分布,以南部方位最多(27.0%),东部方位(26.3%)和西部方位(25.6%)略少,北部方位最少(21.1%);调查幼虫死亡因子,以真菌感染致死最多,占总死亡数的42.4%,细菌和其它因子分别为28%和29.7%。

The cold hardiness of overwintering larvae of Acantholyda posticalis matsumura(Hymenoptera: Pamphiliidae)in Taian

The pine sawfly,Acantholyda posticalis Matsumura is one of the key insect pests foraging on the pine leaves,and it overwinters as larvae in the soil of pine forest.The cold hardiness of overwintering larvae can make direct effects on its population and damage on the pine trees in the next year.The supercooling capability of the overwintering larvae were determined and the location,the stadium and the mortality of the larvae were surveyed during the winter in the pine forest.The results showed that the super...