聚果榕小蜂种内竞争的化学信息调节机制初探

昆虫种内普遍存在着对于交配机会、产卵场所以及食物资源的竞争, 而具信息交流作用的化学物质在调节种内竞争中起着重要的作用。聚果榕(Ficus racemosa)的传粉榕小蜂Ceratosolen fusciceps存在着种内竞争, 我们通过控制榕小蜂在果内能否互相接触(同时、间隔放蜂)的方法进行放蜂实验, 同时用瘿花比例、种子比例、败育花数量和榕小蜂子代数量作为榕小蜂种内竞争的指标, 并用顶空固相微萃取装置和气相色谱–质谱联用仪鉴定分析榕小蜂在雌花期进果前后, 榕果和榕小蜂中的差异性挥发性成分, 重点探讨这些物质在调节榕小蜂种内竞争中的作用。研究结果表明, 同时放蜂所产生的瘿花比例、种子比例和榕小蜂子代数量相较于间隔放蜂显著偏低, 而败育花数量则显著偏多; 化学鉴定结果表明榕小蜂进果前后榕树的挥发性物质的种类存在差异, 在鉴定出来的22种差异物质中, 部分物质对其他种昆虫有抑制产卵的作用。因此, 信息化学物质对榕小蜂的行为可能起着重要的调节作用, 这种作用对于榕小蜂子代和寄主榕树适合度可能都具有重要影响。

Roles of semiochemicals in regulating intraspecific competition of pollinating wasps of Ficus racemosa

Intraspecific competition for mating opportunities, oviposition sites, and food resources is ubiquitous for insects. Semiochemical-based chemical communication may play important roles in the regulation of intraspecific competition. The aims of this study are (1) to investigate the possible occurrence of intraspecific competition among individuals of pollinating fig wasps (Ceratosolen fusciceps) of Ficus racemosa with manipulative experiments, and (2) to assess the potential function of volatile organic compounds (VOCs) in regulating the behavior of fig wasps to avoid excessive competition using head space solid-phase microextraction (HS-SPME) and gas chromatography coupled with mass spectrometry (GC-MS). The results showed that wasps laid more eggs when they were introduced into the syconium sequentially, compared with simultaneously introduced wasps. A chemical analysis showed that the VOCs differed quantitatively and qualitatively. Several of the 22 identified VOCs functioned to deter oviposition in other insect species. Our results indicated that intraspecific competition at oviposition sites may occur among individuals of C. fusciceps and that semiochemicals may play important roles in regulating the oviposition behavior of this species. These factors could significantly affect the fitness of both fig wasps and the host fig.