笔管榕榕小蜂的群落结构与物种多样性

笔管榕为桑科榕属落叶乔木,雌雄同株,为福建地区的常见树种。笔管榕榕果内生活着多种榕小蜂,它们与笔管榕共同构成了榕树-榕小蜂共生体系。通过全年(2011年7月至2012年7月间)对福州地区不同样地的30株笔管榕进行的定时、定点、定株观察与采集,在15批次830个榕果中,共收集到50817头榕小蜂。笔管榕榕果内有7种小蜂,隶属于小蜂总科中的6个科(亚科)7个属,其中榕小蜂科的Platyscapa ishiiana为传粉小蜂,其余6种为非传粉小蜂,分别属于金小蜂科、广肩小蜂科、姬小蜂科及隐针榕小蜂亚科。非传粉小蜂中的Philotrypesis sp.、Acophila mikii、Otitesella ako、Sycophila sp.和Sycobiomorpha sp.小蜂几乎在全年的每个月都可采集到,属常见种。Aprostocetus sp.全年仅收集到2头,为偶见种。笔管榕榕果内的榕小蜂种类在不同月份、不同季节没有明显变化,但不同种类榕小蜂的数量变化明显。在笔管榕榕小蜂群落结构中,全年有9个月均是传粉小蜂占优势,但在1月、9月和11月的采集批次中,非传粉小蜂占优势。非传粉小蜂(Acophila mikii、Sycophila sp.、Philotrypesis sp.和Otitesella ako)常呈爆发性发生,每批次中往往是1-2种的非传粉小蜂数量较多,但不同批次,数量较多的非传粉小蜂种类往往不同,因此在小蜂群落结构中未见某种非传粉小蜂占明显优势。福州地区笔管榕榕果内小蜂群落的的多样性指数为0.72,均匀度指数为0.37,丰富度指数为0.55,优势集中性指数为0.68。分析了6种小蜂的性比,结果表明:传粉小蜂的性比极度偏雌,非传粉小蜂虽然也偏性,但均高于传粉小蜂,推测榕小蜂性比与雄蜂的翅型和交配场所有关。非传粉小蜂的数量和传粉小蜂总数、雌蜂数和雄蜂数均呈极显著负相关,和性比呈极显著正相关关系,说明非传粉小蜂对传粉小蜂的雌、雄蜂都有负面影响,且传粉小蜂雌蜂减少的幅度大于传粉小蜂雄蜂,从而导致其性比升高。非传粉小蜂中Acophila mikii、Sycobiomorpha sp.、Otitesella ako Ishii为造瘿类群,Philotrypesis sp.、Sycophila sp.属于寄居者或寄生者类群,非传粉小蜂中的寄生或寄居类群与造瘿类群相比,对传粉小蜂的负面影响更大。研究结果为榕-蜂协同进化研究,以及城市绿化和生物多样性保护提供科学依据。

Community structure and species biodiversity of fig wasps in syconia of Ficus superba Miq. var. japonica Miq. in Fuzhou

Ficus superba Miq. var. japonica Miq. (Ficus, Moraceae), a kind of deciduous and monoecious tree, is a common tree species in Fujian Province. There are various species of fig wasps in its syconia, constituting a fig-fig wasp symbiotic system with Ficus superba Miq. var. japonica Miq. From July 2011 to July 2012, thirty plants of Ficus superba Miq. var. japonica Miq. from different sites in Fuzhou were observed and collected at regular intervals. A total of 50817 fig wasps were collected from 830 syconia in 15 batches. Seven fig wasp species, belonging to 6 families, 7 genera were found. Platyscapa ishiiana was the unique pollinator, whereas the others were non-pollinating fig wasps, belonging to families Pteromalidae, Eurytomidae, Eulophidae and subfamily Epichrysomallinae, respectively. Among the non-pollinating fig wasps, Philotrypesis sp., Acophila mikii, Otitesella ako, Sycophila sp., Sycobiomorpha sp. were common species, which could be collected almost all year round; whereas Aprostocetus sp. was rare, only two individuals were collected in the whole the year. The fig wasp species in Ficus superba Miq. var. japonica Miq. did not show obvious changes in different months and different seasons, but the numbers of different fig wasp species changed obviously. Among the 12 months of the year, there are 9 months dominated by pollinators, but January, September and November were dominated by non-pollinators. Some species of non-pollinators (Aophila mikii, Sycophila sp., Philotrypesis sp. and Otitesella ako) often occurred explosively. In general, there were 1-2 species dominating in the non-pollinator population in each batch, but the dominant species usually altered across batches. Therefore, there was not a single species consistently dominating among the non-pollinators. The community of wasps in Ficus superba Miq. var. japonica in Fuzhou exhibited a diversity index of 0.72, evenness index of 0.37, richness index of 0.55 and dominant concentration index of 0.68. The sex ratios in the 6 fig wasp species were analyzed. The sex ratio in the pollinator species was extremely biased to female, while those in the non-pollinator species were less biased. It could be inferred that the sex ratio of fig wasps is related to the wing type of male wasps and the place of mating. The number of non-pollinators showed extremely significant negative correlations with the total number of pollinators, the number of female pollinators, and the number of male pollinators, but an extremely significant positive correlation with the sex ratio of pollinators. These results suggest that non-pollinators have negative impacts on both female and male pollinators, but the effect on female pollinators is greater than that on male pollinators, resulting in its sex ratio increased. Among the non-pollinator species, Acophila mikii Ishii., Sycobiomorpha sp., and Otitesella ako Ishii belong to gall-makers, while Philotrypesis sp. and Sycophila sp. belong to inquilines or hyperparasitics, which displayed greater negative impacts on pollinating wasps. The results of this study provide a scientific basis for fig-fig wasps coevolution research, urban greening and biodiversity conservation.