打鬥或求偶？黃斑黑蟋蟀雄蟲 (直翅目:蟋蟀科) 以觸角進行之性別辨識

Abstract

黃斑黑蟋蟀 (Gryllus bimaculatus) 具領域性且好鬥性強，為台灣鬥蟋蟀文化中之打鬥用蟲。在自然情況下，雄蟋蟀與同種蟋蟀個體相遇時會先以觸角碰觸15~30秒以辨識來者性別，而引發後續求偶或攻擊行為。然而，雄蟋蟀是如何由觸角碰觸後，立即明辨對方的性別？因此，本研究將探討雄蟋蟀觸角之性別辨識行為。首先以機械方式刺激雄蟲觸角端部及基部，可知雄蟋蟀觸角端部具有高度的辨識性別能力，辨識雌、雄蟲可達88% 與94% 以上。另外，以掃描式電子顯微鏡細部比較蟋蟀雄蟲觸角基部及端部的感覺毛種類及分佈狀況，發現雄蟋蟀的觸角感覺毛依外部形態構造可分為四種類型，其中機械性感覺受器遍布於觸角各節，而化學性感覺受器於觸角端部較為密集。以化學方式刺激雄蟲觸角端部時，浸泡正己烷的雌蟋蟀觸角，可引發雄蟋蟀產生攻擊行為 (50%)；而浸泡正己烷後再沾附雌蟲體壁濃縮液的雄蟋蟀觸角，可引起雄蟲鳴求偶聲 (35%)。雌、雄蟲觸角的體壁碳氫化合物經氣相層析質譜儀分析後，亦有顯著差異，顯示引發雄蟋蟀的求偶行為與雌蟲的體壁碳氫物有密切關聯。

The male field cricket, Gryllus bimaculatus, is a highly territorial and aggressive species. Under normal conditions, when a male encounters a conspecific individual, it would try to recognize and touch each other by its antennae for 15 to 30 seconds. The result of recognition would lead to further behavior, fight or courtship, depending on the sex of the counterpart. It is interesting to find out how a male cricket discriminates the sex of its encountered cricket immediately after antennal contact? The responses of male cricket by stimulating its antennae with chemical and mechanical stimulants were recorded. Besides, scanning electron microscopy (SEM) was used to examine the sensilla on the distal and basal parts of antennal flagellum of male cricket. The SEM examination showed that there were four types of sensilla on the male crickets’ antennae. The mechanoreceptors were abundant in each segment, and the distribution of chemical receptors was more abundant in the distal part than the basal. The distal part of male crickets’ antenna was the primary region for aggressive (94%) and courtship (88%) responses. The male cricket responses showed that about 50% of the tested male crickets displayed aggressive behavior after contacted by a female antenna which had been washed by n-hexane, and exhibited courtship (35%) after contacted by a male antenna which had been immersed in n-hexane and coated with female cuticular extract. These results suggest that the female cuticular extract may contain contact pheromone for sexual recognition to elicit courtship behavior. The cuticular substances of antennae were then analyzed by gas chromatography and mass spectrometer (GC-MS) to identify the cuticular pheromone.