草地螟阿格姬蜂生物学特性初步研究

Preliminary study of the bionomics of Agrypon flexorius

草地螟阿格姬蜂Agrypon flexorius Thunberg是草地螟Loxostege sticticalis Linne老龄幼虫的优势寄生蜂, 国内外对其研究报道较少。通过田间调查和室内试验，结果表明：雌雄蜂形态相似，雌蜂个体比雄峰略大。23 ℃下，草地螟阿格姬蜂经卵、幼虫、蛹发育到成虫，一个世代历期为30 d-37 d。田间寄生率为3.04%，自然平均性比为3.97：1。羽化在寄主成虫出现一周后开始，第5天达到高峰。 交尾时间一般5 min~10 min。产卵时间一般为1 min~2 min，卵多产在草地螟头、胸部两侧。草地螟阿格姬蜂大多进行两性生殖，少数进行孤雌生殖。在雌蜂不产卵情况下，补充各种营养的成蜂寿命均在16 ℃时最长;22 ℃，补充蔗糖，雌蜂寿命平均为17.11 d。在雌蜂产卵情况下，20%蜂蜜水最适合繁殖。草地螟阿格姬蜂在草地螟4龄幼虫的寄生率最高，平均为40.23%。

A series of experiments on the bionomics of Agrypon flexorius Thunberg （ Ichneumonidae）, a dominant parasitoid of the sugar-beet webworm, Loxostege sticticalis L. , were conducted both in field and laboratory. The developmental duration from egg to adult is 30 -37 days at 23℃. In Inner Mongolia in autumn 2010, the percentage parasitism of L. sticticalis by A. flexorius was found to be only 3.04%. The sex ratio （female/male） of A. flexorius was approximately 3.97： 1. Females and males paired readily 24 hours after emergence. Mating generally lasted 5 - 10 min and peaked when the sex ratio was 1： 1. Mated females began to oviposit one day after mating and the oviposition period was relatively short 1 - 2 min. Eggs were laid in the head and thorax of the host. For the most part, adults adopted bisexual reproduction, but in the absdnce of males, parthenogenesis occurred, which was arrhenotokous. In studies with unmated females, longevity of females on various diets was highest at 16℃ , but at a constant temperature, females lived longest on a diet of cane sugar and shortest when no food was provided. At 22℃ , females lived for 11.7 d when provided with cane sugar. For females which laid eggs on the host, 20% hydromel was the most suitable food for parasitoid longevity and reproduction. The parasitism rate of L. sticticalis by A. flexorius was highest when 4th instar hosts were available. Average parasitism on 4th instar hosts was 40. 23% , and the parasitoid selective coefficient was 0. 47.