Rossbach A, Löhr B, Vidal S
Institute for Plant Pathology and Plant Protection, Entomol. Section, Georg-August-University Goettingen, Grisebachstrasse 6, Goettingen, Germany.
Bull Entomol Res. 2008 Apr;98(2):135-43. doi: 10.1017/S0007485307005482. Epub 2007 Dec 7.
Interspecific competition between an introduced parasitoid species aimed at controlling a herbivorous pest species and a native parasitoid parasitising the same host may influence the success of classical biological control programmes. In Kenya, interspecific competition between an introduced and a local parasitoid on two diamondback moth populations (DBM, Plutella xylostella) was investigated on two different host plants. We tested simultaneous and delayed competition of the local parasitoid Diadegma mollipla Holmgren and its exotic congenus D. semiclausum Hellen on a newly aquired DBM host plant (snowpea) in the laboratory. Under simultaneous competition, D. mollipla produced more progeny than D. semiclausum on snowpea. A head start of D. Mollipla, of four and eight hours before its congenus was introduced, resulted in a similar number of progeny of both species. In delayed competition (time intervals of 24 h, 48 h and 72 h), progeny production was similar for both parasitoids when the time interval was 24 h, irrespective of which species parasitized first. More progeny was produced by the species which attacked first, when the time interval was greater than 24 h, although it was only significant at 72 h. Competitive abilites of both parasitoids on the new host plant differed largely between laboratory and semi-field conditions. The influence of two host plants (snowpea and cabbage) on competition was studied in the greenhouse with different host and parasitoid densities. Parasitism levels of D. semiclausum were significantly higher than those of D. mollipla, regardless of host plant, host and parasitoid densities, but progeny production of D. mollipla on snowpea was still slightly higher than on cabbage. As compared to the confinement of parasitoids and larvae to small containers, D. mollipla parasitized very few larvae in the cages. Competitive ability of the two parasitoid species tested was influenced both by the density of the searching females and by parameters related to either the host plant and/or the herbivorous hosts.
旨在控制一种食草害虫的外来寄生蜂物种与寄生同一寄主的本地寄生蜂之间的种间竞争，可能会影响经典生物防治计划的成效。在肯尼亚，研究人员在两种不同的寄主植物上，对外来寄生蜂和本地寄生蜂在两个小菜蛾种群（小菜蛾，Plutella xylostella）上的种间竞争进行了调查。我们在实验室中，在一种新获得的小菜蛾寄主植物（荷兰豆）上，测试了本地寄生蜂莫氏迪亚姬蜂Diadegma mollipla Holmgren及其外来同属物种半闭迪亚姬蜂D. semiclausum Hellen的同时竞争和延迟竞争情况。在同时竞争的情况下，在荷兰豆上，莫氏迪亚姬蜂产生的后代比半闭迪亚姬蜂更多。莫氏迪亚姬蜂在其同属物种引入前4小时和8小时先行开始寄生，结果两个物种产生的后代数量相似。在延迟竞争（时间间隔为24小时、48小时和72小时）中，当时间间隔为24小时时，无论哪个物种先寄生，两种寄生蜂的后代产量都相似。当时间间隔大于24小时时，先攻击的物种产生的后代更多，不过只有在72小时时才具有显著差异。两种寄生蜂在新寄主植物上的竞争能力在实验室条件和半田间条件下差异很大。在温室中，研究了两种寄主植物（荷兰豆和卷心菜）在不同寄主和寄生蜂密度下对竞争的影响。无论寄主植物、寄主和寄生蜂密度如何，半闭迪亚姬蜂的寄生水平均显著高于莫氏迪亚姬蜂，但莫氏迪亚姬蜂在荷兰豆上的后代产量仍略高于在卷心菜上的产量。与将寄生蜂和幼虫限制在小容器中相比，莫氏迪亚姬蜂在笼子里寄生的幼虫很少。所测试的两种寄生蜂物种的竞争能力，受到搜寻雌蜂的密度以及与寄主植物和/或食草寄主相关的参数的影响。
