桉树枝瘿姬小蜂入侵生殖策略的研究

Reproductive models of invasive insects are multiple that is advantage of their colonization, reproduction, and diffusion. Leptocybe invasa Fisher et La Salle (Hymenoptera: Eulophidae), an indigenous species in Australia, is an important invasive pest of Eucalypti in the world. Successful invasion of this species was attributed to lacking of natural enemy, plentiful supply of food, strong adaptability and particular reproductive model in the invaded habitat. Leptocybe invasa has the sexual reproduction and parthenogenesis in the same region, but which model would be adopted under the specific environment is unclear, and these results are the key for analyzing the mechanism of population outbreaks of this species. In this study, reproductive strategies of natural population in L. invasa will be investigated to explore the environmental factors that may affect its reproductive strategies. Meanwhile, the reproductive strategies will also be induced by different environmental conditions in laboratory, including population density, number of male, temperature, and photoperiod. Based on the results from field and laboratory, we can affirm the reproductive strategies of L. invasa under different conditions, which will provide new clue for analyzing the mechanisms of invasion and population outbreaks of the pest.

入侵性昆虫常具有多种生殖方式，利于其在入侵地迅速定殖、繁殖和扩散。桉树枝瘿姬小蜂Leptocybe invasa Fisher & La Salle起源于澳大利亚，现已是全球桉树上的一种重要入侵性林业害虫，该蜂的成功入侵和爆发危害不仅归因于缺乏有效天敌的抑制、拥有丰富的食料和较强的适应能力，可能还与其生殖方式有关。该蜂具有孤雌和两性生殖方式，但在不同环境下该蜂采用何种生殖对策尚不清楚，而弄清这点是解析其种群爆发危害的关键之处。本项目调查我国不同地区桉树枝瘿姬小蜂自然种群的生殖策略，寻找可能影响其生殖对策的环境因子；并在室内以孤雌和两性生殖种群为材料，通过人工创造种群密度、异性数量、温度和光周期的诱导环境，开展诱导环境下该蜂生殖策略的研究。基于野外和室内的研究结果，可探明我国桉树枝瘿姬小蜂在不同环境下的生殖策略，为深入解析该蜂入侵和种群爆发的机制提供新的线索。

桉树枝瘿姬小蜂Leptocybe invasa Fisher & La Salle是全球桉树上的一种重要入侵性林业害虫，在我国已扩散至福建、广东、海南、广西、江西和四川。推测该蜂的快速扩散和种群爆发与其生殖方式有关。本项目研究了我国该蜂不同地理种群自然条件下的生殖方式及不同诱导环境下的生殖方式。结果表明：自然种群及其子代性比均显著偏向于雌性；雌虫卵巢为卵熟型；刚羽化的处女雌虫无需交配即可正常产卵致瘿，且后代可正常生长发育；种群密度和季节性环境条件的变化不会诱导其生殖方式的转变。结果证明该蜂营孤雌生殖，是导致其种群快速扩散和种群爆发的原因之一。