Symbiosis and Population Dynamics of the Fig Wasps Associated with Ficus pedunculosa var. mearnsii

• Main Authors: Po-An Chou, 周柏安
• Other Authors: Hsy-Yu Tzeng
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/72590067836843141313

碩士 === 國立中興大學 === 森林學系所 === 105 === The relationship between Ficus and Agaonid wasps (excluding Sycophaginae) is an obligate mutualism. Both of them have developed high specificity at species level. Except Agaonid wasp, there are many Chalcid wasps called non-pollinating fig wasps (NPFWs) exploiting the resources of fig but not offer any reward for Ficus. Moreover, NPFWs usually have negative effects on the mutualism. Because of pollinator’s short life, there are many different phenological pattern to stabilize the population of pollinator. This study focuses on a dioecious fig shrub, Ficus pedunculosa var. mearnsii, and its associated fig wasps (pollinator: Blastophaga pedunculosae; NPFW: Apocrypta sp.), surveying the phenology of two populations of this plant, the interaction and population dynamics of these two fig wasps species in Kenting and Jialeshui, south Taiwan from March 2015 to March 2017. The phenology shows that both male and female trees flushed new leaves and produced figs in the whole year with some seasonal peaks. There was only one fig number peak in summer from female trees, while many scattered peaks were observed in male trees. Both populations exhibited different fruiting trends and had different responses to temperature and rainfall linked with the topographic and climate difference of the two habitats. In the fig wasps interaction part of this study, the only NPFW, Apocrypta sp., is inferred to be a parasitoid, could significantly decrease the pollinator number in male figs. Fig wall thickness cannot be an efficient defensive strategy to prevent Apocrypta sp. oviposition. Although there are partial predation on female pollinator by Apocrypta sp., this NPFW cannot affect pollinator sex ratio significantly. The population dynamics study of these two fig wasps shows that the pollinator population peaked in correspondence with peaks of receptive figs of both sex, and exhibited related trends with receptive figs of the previous generation, pollinator number of last generation and the Apocrypta sp. population. Wasps of both habitats are much more abundant than the minimum number which could keep the female flowers of both sex fig well-utilized (80%), but shortage occurred several times. Besides, there were not any mature male fig produced in Jialeshui, thus the pollinator population may become local extinct. This study confirmed the interaction between both fig wasps and compared the responses of plant phenology and pollinator population under the same climate events, these results can offer important information for maintaining fig-fig wasps symbiosis under extreme climate.