爱玉子上幼期爱玉子榕小蜂与虫瘿的协同发育

Synergetic development of immature Wiebesia sp.nr.pumilae and its gall on Ficus pumila var.awkeotsang

【目的】特种果树爱玉子Ficus pumila var.awkeotsang依赖榕小蜂传粉方能结实。本研究旨在了解爱玉子榕小蜂Wiebesia sp.nr.pumilae及其虫瘿发育动态,为榕小蜂发育生物学研究奠定基础。【方法】通过人工放蜂-标记-定期采样-显微镜和电镜观测的方法,观察爱玉子榕小蜂-虫瘿协同发育过程以及爱玉子榕小蜂在虫瘿内的营养来源和位置变化,测定了爱玉子榕小蜂体长与虫瘿直径的发育动态,比较了冬季和夏季爱玉子榕小蜂的发育历期。【结果】幼期爱玉子榕小蜂发育分为卵期、幼虫期和蛹期。幼虫分为5龄,无法分辨雌雄;蛹分为初期蛹、中期蛹和成熟蛹,雌雄蛹异形分化,雄蛹发育早于雌蛹1.34 d。虫瘿由表皮层、保护层、内皮层、营养层组成。表皮层和内皮层均胶质化,富含水分,为小蜂提供良好的湿度保障;保护层是虫瘿壳的骨架,具有保护幼虫的作用;营养层分泌营养液供幼虫吸食。与瘦果结构比较表明,小蜂造瘿改变了壳的形态,增厚了保护层,并使营养层具备向榕小蜂幼虫输送营养液的功能。幼期小蜂在虫瘿内的位置呈规律性变化。小蜂幼虫体长与虫瘿直径协同增长,但虫瘿增长先于幼虫,为幼虫发育提供了充足的生长空间。小蜂发育进入蛹期后体长不再增长,而虫瘿在4龄幼虫期后停止生长。在福建地区爱玉子榕小蜂一年2代,冬、夏季爱玉子榕小蜂世代历期分别为253和112 d,冬季世代各阶段发育历期均比夏季世代长,尤其冬季5龄幼虫期比夏季的延长了66 d,冬季以5龄幼虫越冬,延长了进食期有利越冬。【结论】研究结果明确了幼期爱玉子榕小蜂与虫瘿间的营养联结与协同发育动态,为榕树-榕小蜂协同进化研究提供理论依据。

【Aim】Ficus pumila var.awkeotsang,a special fruit tree,relies on Wiebesia sp.nr.pumilae for pollination.The aim of this study is to investigate the developmental dynamics of galls and W.sp.nr.pumilae,thus providing a foundation for further studies on the developmental biology of fig wasps.【Methods】By means of artificially releasing wasps-marking-regularly sampling-microscopic and electron microscopic observations,the synergistic development of W.sp.nr.pumilae with gall,and the source of nutrients and the position change of W.sp.nr.pumilae inside galls were observed,the developmental dynamics of the body length of W.sp.nr.pumilae and the diameter of gall was determined,and the developmental duration of W.sp.nr.pumilae in summer and winter was compared.【Results】The development of immature W.sp.nr.pumilae is generally divided into the egg,larval and pupal stages.The larval stage is divided into 5 instars,in which male and female are indistinguishable.The pupal stage is divided into three stages:early stage,middle stage and mature stage.Male and female pupae are differentiated and heteromorphic,and male pupae develop 1.34 d earlier than female pupae.The gall consists of epidermis,protective layer,endodermis and nutritive layer;both the epidermis and endodermis are colloidal and water-rich,providing good humidity guarantee for fig wasps.The protective layer,as the skeleton of the gall shell,protects the larval wasps.The nutritive layer secrets nutritive solution to feed larval wasps.A comparison with the structure of the lean fruit showed that the small wasp-galls changed their protective layer morphology with thickened protective layer,and the nutritive layer is capable to deliver nutritive solution to larval fig wasps.The position of immature fig wasps inside the gall is regularly varying.The body length of larval wasps increases synergistically with the diameter of the gall.Galls grow faster than wasp larvae to provide a bounteous growth space for them.The body length of the fig wasp stops increasing in the pupal stage,while the growth of galls stops after the 4th instar of the larva.In Fujian areas,W.sp.nr.pumilae has two generations a year,its generation time in winter and summer is 253 d and 112 d,respectively,and the duration of various developmental stages in winter is longer than that in summer.Especially,the duration of the 5th instar larva of W.sp.nr.pumilae in winter is 66 d longer than that in summer.W.sp.nr.pumilae overwinters in the form of the 5th instar larva,and a prolonged feeding period is beneficial for its overwintering.【Conclusion】The results clarified the nutritive connection between immature W.sp.nr.pumilae and its gall and their synergistic development dynamics,providing a theoretical basis for the study of fig-fig wasp coevolution.