两种共存网蛱蝶幼期的生命表研究

Life tables of immature stages of two coexisting melitaeine butterflies Melitaea phoebe and Euphydryas aurinia (Lepidoptera: Nymphalidae)

在河北省赤城县大海坨国家自然保护区内,从2002年到2004年应用生命表方法研究了在同一网络斑块中共存的金堇蛱蝶Euphydryasaurinia和大网蛱蝶Melitaeaphoebe两个世代的幼期各阶段的死亡情况,目的是了解影响种群动态的重要因子,为它们的长期保育提供信息。结果表明,金堇蛱蝶幼期总累积死亡率都较小,两个世代分别为59%和72%;而大网蛱蝶总累积死亡率较高,两个世代分别为89%和80%。影响大网蛱蝶死亡的最重要因子是放牧,两个世代与放牧相关的k值分别为0.559和0.167;尤其是在越冬后大网蛱蝶幼虫组聚集取食阶段,导致两个世代分别有50%和25%的幼虫组死亡。寄生蜂在大网蛱蝶小种群下也分别使两个世代4%和9%的5～6龄期幼虫以及13%和24%的蛹死亡。金堇蛱蝶死亡主要发生在越冬期,与越冬死亡相关的k值两个世代分别为0.073和0.199,而寄主植物的质量影响越冬期幼虫组死亡;寄生蜂则对金堇蛱蝶种群的调控作用极小,只有在2003～2004世代有4.0%的越冬后幼虫被寄生和7%的蛹被寄生。影响两种蛱蝶种群动态的关键因子不同,采取的保护措施应有所不同。在春季减少源斑块内的放牧,对于以源汇集合种群形式存在的大网蛱蝶种群恢复和增长十分必要;而对以经典集合种群形式存在的金堇蛱蝶,通过适当植被管理提高繁殖区域内寄主植物质量,可以提高越冬期幼虫组存活率,有利于其长期持续生存。

From 2002 to 2004, in Dahaitou National Natural Reserve, Chi Cheng county, Hebei province, mortality was surveyed for all immature stages of the two coexisting melitaeine butterflies Melitaea phoebe and Euphydryas aurinia for two generations in the same habitat network. Life tables were constructed to explore the effects of the main mortality factors on population dynamics. The results showed that the total mortalities of two generations of M. phoebe （89% in the 2002 - 2003 generation, and 80% in the 2003 - 2004 generation） were higher than those of E. aurinia （59% and 72% respectively）. For M. phoebe, mortality due to grazing was the most important factor, especially during the post-hibernating larval period. The k value for grazing was 0.559 and 0. 167 respectively during the two generations. Even in the small populations, the parasitoids caused some post-diapause larvae （4% and 9% for the two generations respectively） and pupae （13% and 24% ） to death. For E. aurinia, mortality during hibernation was the highest and the k value for the two generations was 0.073 and 0.199 respectively, which was influenced by host plant quality. In contrast, parasitoids had little effect on the population regulation, because only 4% of the post-diapause larvae and 7 % of the pupae were dead due to parasitoids in the 2003 - 2004 generation. These results suggested that different conservation strategies should be taken for the two butterflies. For M. phoebe, to decrease grazing, especially its effects on the source population during the pest-hibernating larval group stage, is crucial for its population restoration and growth. For E. aurinia, however, improvement of the host plant quality by habitat managements in breeding areas, which could increase the survivorship during the hibernation period, is helpful for its long-term persistence and conservation.