垂叶榕上16种榕小蜂的种群动态

传粉榕小蜂和榕树的互利共生是传粉昆虫与植物间协同进化的典范。在榕果(榕树的隐头状花序)内,还生活着多种非传粉榕小蜂。这些生活在密闭榕果内由传粉榕小蜂和非传粉榕小蜂组成的群落对研究群落生态学有很大价值。然而,对生存在单一榕树的榕果内的所有榕小蜂的种群动态了解很少,特别是缺少相对长期的连续数据。通过野外近3a观察和采样,研究了垂叶榕榕小蜂群落结构和榕小蜂的种群动态。共记录榕小蜂16种;各种榕小蜂根据发生规律可分为常见种和偶见种,Eupristina koningsbergeri,Philotrypesis sp.1,Philotrypesis sp.4,Philotrypesis sp.5,Sycoscapter sp.1,Walkerella benjamini,Walkerella sp.1,Sycophila sp.2,Sycobia sp.2为常见种;Sycobia sp.1,Acophila sp.1,Sycophila sp.1,Ormyrus sp.1等为偶见种。每种榕小蜂在单果上的数量随季节呈波动变化,季节对榕小蜂群落的多样性和均匀性无显著影响。除了传粉榕小蜂外,Sycoscapter sp.1也是优势种类之一。传粉榕小蜂的数量与非传粉榕小蜂总数间呈显著负相关。传粉榕小蜂与非传粉榕小蜂几乎都呈负相关,而与Walkerella sp.1在数量上呈显著正相关。Sycobia sp.2与Sycophila sp.2在同一瘿中出现,数量上呈显著正相关。但其它非传粉榕小蜂种类在数量上的相关性较为复杂,可能是造成各种榕小蜂数量波动的一个原因。

Population dynamics of 16 fig wasp species in Ficus benjamina

The mutualism between figs and pollinating fig wasps is a classic example for studying the origin, equilibrium mechanisms and evolution of mutualism, resource conflicts, and sex allocation. Figs (Ficus spp.) depend on wasps for transmission of their pollen, and fig wasps depend on fig inflorescences (syconia) for the completion of their life cycles. Non-pollinating fig wasps also live in figs, with different influences on the mutualism due to different biological habits. These communities, which consist of pollinating and non-pollinating fig wasps in the closed syconia, could be valuable for studies of community ecology. However, we have little knowledge about the population dynamics of the entire community of species associated with single fig species, especially over the long term. We have investigated community structure of fig wasps exploiting syconia of Ficus benjamina, a monoecious, commonly cultivated tree, for about 3 years in Chinese Academy of Tropical Agricultural Sciences, Danzhou, Hainan Province. We collected and dissected the mature figs from the surrounding trees, sought out all wasps even if some of them were still living in galls, identified the species and counted individuals. We found 16 species of fig wasps, including one obligate pollinator, Eupristina koningsbergeri, and 15 non-pollinating fig wasps belonging to 8 genera of Chalcidoidea, including 1 newly recorded species of Sycoscapter and 2 new records of Sycophila. Common species included Eupristina koningsbergeri and such non-pollinating fig wasps as Philotrypesis sp.1, Philotrypesis sp.4, Philotrypesis sp. 5, Sycoscapter sp. 1, Walkerella benjamini, Walkerella sp. 1, Sycophila sp. 2 and Sycobia sp. 2. The pollinator was dominant and nearly as frequent as the non-pollinators, with a large range of variation in number among months. Besides the pollinator, Sycoscapter sp. 1 made up the largest proportion of non-pollinators, while Philotrypesis sp. 5 was the rarest. The other 7 species were only occasionally caught, including Sycoscapter sp. 2, Sycobia sp. 1, Acophila sp. 1, Sycophila sp. 1, Sycophila sp. 3, Sycophila sp. 4, Ormyrus sp. 1. These species were not present every month, and fewer than 10 wasps of each were recorded per fig. The presence of these species usually did not distort the number of other common species. But when resources were limited, with small populations of the community, the occasional species had influence on the common non-pollinators. All the fig wasps varied in population density per syconium across months. A maximum of 589 fig wasps were found in a single fig, and 155.38 on average in wet season. While in dry season the numbers were 335 and 99.84 per fig. But there were no significant changes in the community structure between dry or wet seasons. The number of pollinators was negatively correlated with those of each of the non-pollinating fig wasps, except for Walkerella sp. 1, which was positively correlated with the pollinator. Sometimes, Sycobia sp. 2 and Sycophila sp. 2 both occurred in the same gall, and were positively correlated in number. However, the numerical relationships among the other non-pollinating fig wasps were very complicated. We will examine relationships among these non-pollinating fig wasps in the future.