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

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.