松墨天牛是否存在雌性接触信息素?

Does the contact sex pheromone of Japanese pine sawyer, Monochamus alternatus, exist?

将松墨天牛Monochamus alternatus Hope的身体不同部位切除之后的交配试验显示，分别剪去头部、鞘翅以及前胸部后仍然可以正常交配，用雄虫的腹部代替雌虫的腹部后，仍然能够引起雄虫的交配趋势动作，但不能完成真正交配，因此推测雌性接触信息素如果存在，主要集中在雌虫身体后半部，尤其是中后胸部位。但是冻死后的雌虫不再引起雄虫的交配行为，而且冻死的雌虫与活雌虫同时放入培养皿中，雄虫喜欢与活雌虫交配，不选择冻死的雌虫，因此推测视觉在其松墨天牛的交配过程中扮演着重要的角色，而接触性信息素有可能并不存在。将雄虫的触角分别从第5～6节和第1节剪去的试验结果显示，雄虫仍然可以很快地找到雌虫，发生交配行为。这有2种可能的解释：一是雄虫不仅仅靠触角来感受雌虫的接触信息素，头部下颚须和下唇须上或者足上也有可以感受信息素的感受器；二是雌虫不存在接触信息素，雄虫通过视觉就可以找到对方，完成交配过程。浸泡致死的雌虫不再引起雄虫的交配行为，并且将正己烷和乙醚的浓缩液滴加在浸泡致死的雌虫以及玻璃棒和鹅卵石的生测试验结果显示，都没有引起雄虫的交配行为。这进一步说明，松墨天牛可能并不存在体表接触信息素。性成熟后的松墨天牛雌雄成虫是靠衰弱寄主的强烈的挥发性气味聚集到寄主树干上，在树干这个较为狭小的环境里，有可能是通过视觉找到配偶，完成交配过程。

A series of experiments with different body parts of females Monochamus alternatus Hope separately dissected showed that after head, elytra and prothorax of females were separately dissected, or replacing the abdomen of females with that of males, females still elicited the mating behavior of males. This implied that if contact sex pheromone exists, it should be accumulated on the second half part of body of female M. alternatus, especially thorax. However, dead females killed by freezing did not elicited the response of males, and when both live and dead females killed by freezing were offered to males, all males preferred live females, further evidence suggests that contact sex pheromone does not exist in M. alternatus, and visual cues may play an important role in the mating behavior of M. alternatus since the movement of female beetle attracts male. When antennae of males were dissected at No. 5-6 segment and No. 1 segment of antennae, males still succeeded in finding females to finish the mating behaviors. This suggests that either contact sex pheromone does not exist or males perceive pheromone on the receptors of maxillary and labial palps. Dead females from extraction with hexame did not also elicit the response of males. When the whole body was extracted with hexane or ether, both extracts dripped on dead females due to extract, glass sticks and cobblestones did not elicit the response of males. Further evidence showed that the contact sex pheromone maybe does not exist in the body of M. alternatus. Mature females and males aggregate on host stem by perceiving the host volatiles. In the small environment of host stem, visual cues may play an important role in the following mating behavior of M. alternatus.