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Ficus virens Ait.var.sublanceolata is a common monoecious landscape trees in Fuzhou.In this study,the structure and biodiversity of fig wasp community inside syconia of F.virens Ait.var.sublanceolata were investigated based on 10 plants at two selected sites in Cangshan and Minhou town of Fuzhou.A total of 13458 fig wasps were collected from 267 syconia in different seasons.Seven fig wasp species were found,which belonged to Agaonidae,Epichrysomallinae,Otitesellinae,Sycoryctinae,Eurytomidae,Ormyridae and Eulophidae of Chalcidoidea,respectively.Among them,only Platyscapa coronata of Agaonidae served as a pollinating agent for F.virens Ait.var.sublanceolata through a way of active pollination.Male polymorphism was common in the non-pollinating fig wasps.Both pollinating and non-pollinating fig wasps showed female-biased sex ratios.The sex ratio of pollinating fig wasps was 0.19±0.07,and the sex ratios of non-pollinating fig wasps Camarothorax bismasculinus,Walkerella sp.,Sycoscapter sp.and Sycophila sp.were 0.36±0.10,0.36±0.22,0.31±0.22 and 0.35±0.13,respectively.Male polymorphism may be one of the reasons for the increase of sex ratio in the non-pollinating wasps.According to the number and continuity of occurrence,fig wasps could be classified into common species and occasional species.Platyscapa coronata,Camarothorax bismasculinus,Walkerella sp.,Sycoscapter sp.and Sycophila sp.were common species,while Omyrus sp.and Aprostocetus sp.were occasional species.The presence of occasional species had little effect on the number of common species.Occasional species might use the unsaturated part of the resources in the fig fruit.It might also be that the fig fruit reserved space and resources for the occurrence of the occasional species.It was the first time that a certain number of Eulophidae parasitic insects were found in fig fruits.This provides the basic data for the taxonomy and the research of biological and ecological characteristics of Eulophidae insect. The wasp community composition and structure differed greatly across seasons.In winter and spring(from December to May of next year),there were more species and higher numbers of fig wasps inside syconia,among which pollinating fig wasps were the dominant species with an importance index up to 0.42.This resulted in a high setting rate of fig seeds.In summer and autumn(from June to November),there were fewer species and lower numbers of fig wasps inside syconia,among which Camarothorax bismasculinus and Sycophila sp.were dominant species with importance indexes up to 0.56 and 0.28,respectively,whereas the importance indexes of pollinating wasps was only 0.025.During this period,it was difficult to find pollinating wasps in the fig.Therefore,the setting rate of fig seeds was lower.The large proportion of non-pollinating had a great negative impact on the reproduction of Ficus virens Ait.var.sublanceolata.Rain and high temperature might be the main causes of the dramatic decrease of the number of pollinating fig wasps inside syconia during the summer and autumn seasons.There were no significant differences in community structure and its annual change between the two sites.The results of this study provide a scientific basis for the urban greening and biodiversity conservation in tropical rain forests. |
