伪鞘榕小蜂雌雄成虫触角感器的超微形态、分布及适生意义

Ultramorphology,distribution and ecological significance of antennal sensilla of female and male Sycoscapter trifemmensis(Hymenoptera:Pteromalidae)

伪鞘榕小蜂Sycoscapter trifemmensis是一种寄生于鸡嗉子榕间花期榕果的专性寄生蜂,雌雄两性繁殖策略分化明显,为更好理解和诠释雌蜂寄主定位和雄蜂配偶识别机制,有必要对两性的触角感器进行观察。运用环境扫描电镜观察,对比和探讨了伪鞘榕小蜂雌雄成虫的触角和触角感器类型、分布、数量及其生态适应性。结果表明:雌蜂触角鞭节由11鞭小节组成,总长817.82±33.23μm,分布有毛形感器、刺形感器(类型1)、锥形感器(类型1)、多孔板形感器(类型1)、栓锥形乳突状感器5类5种;雄蜂触角鞭节仅由6鞭小节组成,全长为雌蜂的1/3,且各节有明显的缩短和增粗特征,着生感器包括毛形感器、刺形感器(类型2和类型3)、锥形感器(类型1和类型2)、多孔板形感器(类型2)、腔锥形感器5类7种。雌蜂触角感器的数量与分布显著高于雄蜂,且同类型感器在雌蜂上具有明显的延伸、增粗、分支的特征,以板形感器和锥形感器最为突出。伪鞘榕小蜂雌雄成虫的触角及其感器有明显的性二型,特别是与化学信息识别相关的感器,反映了雌雄蜂在不同生态环境和繁殖压力下的形态分化、行为策略和生态适应。

Sycoscapter trifemmensis is a species-specific parasite at the interfloral stage of Ficus semicordata.Female and male wasps obviously show the difference in the reproductive strategies.To understand more in female host location and male mate recognition,it is necessary to conduct the observation on the sensory organs on the antenna of S.trifemmensis.Environmental scanning electron microscopy was used to get sensillum characteristics,including type,ultramorphology,distribution,and abundance on the antenna of female and male wasps.Ecological significance of different sensilla was also discussed on basis of its evolutional pressures and behavioral patterns.The length of female antenna is 817.82±33.23μm,and the flagellum consists of 11 flagellomeres.Five distinct sensory organs occurs on the antennae of females,including trichoid sensilla,chaetica sensilla(types 1),basiconic sensilla(type 1),multiporous placoid sensilla(type 1),basiconic capitate peg sensilla.For males,the length of antenna is about to 1/3 as against females,and the flagellum is composed of six flagellomeres.Each subsegment shows the shortening in length and thickening in width,respectively.Seven morphological types of antennal sensilla on the males were identified,including trichoid sensilla,chaetica sensilla(types 2&3),basiconic sensilla(type 1&2),multiporous placoid sensilla(type 2),and coeloconic sensilla.As expected,females have more sensory organs than males on the whole antennae and the same segment.Further,the size of some of the same sensillar types on the females is enlarged through the lengthening,branching and thickening,particularly like as multiporous placoid sensilla and basiconic sensilla perceived chemical cues.The antennae and antennal sensilla of S.trifemmensis showed the classical sexual dimorphism.Because of difference in ecological environment and reproductions for females and males,their chemical sensilla have evolved the morphological adaptation which match up with the evolutional pressures,behavioral strategies and ecological relationship.