桑盾蚧盗瘿蚊的研究

A PRELIMINARY STUDY ON SCALE-EATING GALLE MIDGE (Lestodiplosis pentagona Jiang, nov. sp. )

对桑盾蚧盗瘿蚊(Lestodiplosis pentagona Jiang nov.sp.)的形态特征、生活习性及其与桑盾蚧的关系等进行了探讨。该虫为捕食桑盾蚧的天敌,幼虫捕食桑盾蚧的卵、雄蛹和雌成虫,并以幼虫、蛹在介壳下越冬。成虫日间均可羽化,以黄昏为最盛;具有趋光性和补充营养期,性比随羽化时刻、季节与地区而异,但总体上雌虫多于雄虫。幼虫耐饥,无猎物亦可化蛹直至羽化;具有趋湿性和环境引起的群集性;其分布数量与雌蚧密度呈极显著正相关,相关系数为0.9843。试验结果表明:在室内保护条件下,对桑盾蚧的捕食率可高达93％以上,为自然状态的4倍;不同杀蚧剂对该虫的毒性不同,如柴油(原液)毒性很大,洗衣粉液(10倍)毒性较轻。保护天敌和筛选杀蚧剂非常重要。

A scale-eating galle midge (Lestodiplosis pentagona Jiang ,nov. sp. ) was tound for the first time in Sichnan province. Its morphology, biological habits, predaceous rations to P. pentagona have been initially studied in this paper . L. pentagona is a superior predaceous natural enemy of P. pentagona, its larva can eat the pest's eggs, male pupa and female adult, and the larva or pupa live though winter inside pest scale. The adult can emerge all around day, but mainly at dusk. The adults have phototaxis and need for supplement nutrients. Its sexual ratio varies with the emerging time, seasons and area but generally there are more females than males. The larva can resist hunger untill pupation and adult emergence without sufficient preies. The larva has moisturetaxis and aggregation caused by environment. Its distribution is very positive relative to the density of the female scale. The interrelated coefficient is 0. 9843. The results show that the predatory rate is more than 93% under lab condition, as 4 times as in nature. Toxicity of dieseloil is so violent, but the toxicity of the washing powder is lower, which showes that it is essential to protect natural enemies and select scalecide.