小菜蛾重要寄生蜂——半闭弯尾姬蜂在中国的地理分布

An investigation of geographic distribution of Diadegma semiclausum, a major parasitoid of the diamondback moth, Plutella xylostella, in China

半闭弯尾姬蜂Diadegma semiclausum 是小菜蛾Plutella xylostella的一种主要寄生蜂,在气温较温和的地区可对小菜蛾种群起到明显控制作用。文献中未见该蜂在中国自然分布的记录。在北京、山东、河南、山西、宁夏、新疆等地采得的一种弯尾姬蜂与澳大利亚引进的半闭弯尾姬蜂形态特征一致。对中国北京和澳大利亚昆士兰两地的弯尾姬蜂种群进行了杂交试验,种群间正交、反交和回交的子代数和雌性比与种群内交配的无显著差异,表明这两个地理种群在生殖上完全亲和,属同种。这是首次以形态学和遗传学证据证明半闭弯尾姬蜂这一重要天敌在中国广泛分布。

Diadegma semiclausum(Hellen)(Hymenoptera:Ichneumonidae) has been recorded as a major parasitoid of the diamondback moth,Plutella xylostella(Linnaeus)(Lepidopter-a:Plutellidae).This parasitoid can exert substantial control on P.xylostella populations in areas with a mild temperature.In the literature there has been no record of natural distribution of this parasitoid in China.A Diadegma species collected from Beijing,Shandong,Henan,Shanxi,Ningxia and Xinjiang showed morphology identical to that of D.semiclausum collected from Queensland,Australia.Crossing trials were conducted between a Beijing Diadegma population and the Queensland D.semiclausum population.Number of viable progeny and sex ratio of progeny in all cross and back cross combinations were comparable to those of intra-population crosses,demonstrating that the two geographic populations of the parasitoid remain completely compatible in reproduction and belong to one well-defined species.This study represents the wide distribution of D.semiclausum in China,validated by evidence of both morphology and genetics.