圆柏大痣小蜂羽化的生态学特性及幼虫空间分布

Ecological characteristics of Megastigmus sabinae Xu et He and the spatial distribution of its larvae

[目的]圆柏大痣小蜂Megastigmus sabinae Xu et He以幼虫在祁连圆柏健康球果内蛀食胚乳,并随球果同步发育,致使种子成熟后有果无仁,造成种子质量严重下降,严重影响祁连圆柏生产。为准确掌握圆柏大痣小蜂生物学及生态学特点。[方法]在祁连山北坡东段布设样地,随机选取样株,进行圆柏大痣小蜂羽化特性及幼虫空间分布研究。[结果]在甘肃省祁连山地区,圆柏大痣小蜂羽化高峰期为7月17—7月24日,羽化数随温度的升高、湿度的降低而增加,环境温度为22.9℃时羽化数最多,但当达到最大羽化数后,温度和湿度的变化对羽化数的影响不明显;羽化初期雄虫多于雌虫,羽化后期雄虫数明显减少;圆柏大痣小蜂幼虫在祁连圆柏树冠中部幼虫量显著高于树冠上部和下部,树冠中部的幼虫数占总幼虫数53.29%,幼虫在树冠在东、南、西、北方位上所占的比例分别为58.47%、64.66%、30.12%、27.48%。[结论]圆柏大痣小蜂羽化与温度湿度密切相关,幼虫在祁连圆柏树冠上具显著的方向性分布特征。

[Objectives] To determine key biological and ecological characteristics ofMegastigrnus sabinae Xu et He, the larvae of which damage the endosperm of healthy cones of Sabina przewalskii resulting in a serious decline in seed quality. [Methods] The eclosion characteristics and spatial distribution of M.sabinae larvae were investigated in the eastern section of the northern slopes of the Qilian Mountains, Gansu Province. [Results] The peak of eclosion occurred between 17 July and 24 July. The number of eclosion increased with decreasing temperature and humidity, reaching a maximum at an ambient temperature of 22.9~C, after which changes in temperature and humidity had no obvious influence on the number of eclosion. Males emerged earlier than females and significantly fewer males emerged later. Larvae in the middle of the canopy were significantly more abundant than in the upper and lower parts, accounting for 53.29% the total number of larvae. Relative larval abundance in the eastern, southern, western, and northern sides of the canopy were 58.47%, 64.66%, 30.12% and 27.48%, respectively. [Conclusion] Eclosion of M. sabinae is closely related to temperature and humidity, and aspect significantly affects the distribution of larvae.