Yu Pei, Cao Chengquan, Liu Xingyue, Hayashi Fumio
Department of Biology, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji 192-0397, Tokyo, Japan.
College of Life Science, Leshan Normal University, Leshan 614004, China.
Insects. 2023 Jan 13;14(1):86. doi: 10.3390/insects14010086.
Chemical secretions are an effective means by which insects may deter potential enemies, already being studied extensively with regard to their chemicals, synthesis, toxicity, and functions. However, these defensive secretions have been little studied in Megaloptera. Herein, the fluid expelling behavior of adult alderflies (Sialidae), fishflies (Corydalidae: Chauliodinae), and dobsonflies (Corydalidae: Corydalinae), all of the order Megaloptera, is described in detail regarding the timing and possible function of this behavior. When disturbed artificially, both males and females could expel fluid from the anus. However, the frequency of expelling was much lower in alderflies than in fishflies and dobsonflies. The amount of expelled fluid relative to body weight was also smaller in alderflies. In fishflies and dobsonflies, the amount of expelled fluid decreased with adult age, probably because the fluid is little replenished once expelled. The cream-colored fluid seems to be meconial fluid produced via the Malpighian tubules at the pupal stage, which is usually discharged at adult emergence in most other holometabolous insects. However, adult fishflies and dobsonflies often expel it vigorously by bending their abdomen when disturbed after emergence. Thus, the fluid expelling may be an anti-predatory behavior, particularly in younger adults that can expel a relatively large amount of fluid.
化学分泌物是昆虫用以威慑潜在敌人的一种有效手段，目前人们已针对其化学成分、合成、毒性及功能展开了广泛研究。然而，对于广翅目昆虫的这些防御性分泌物却鲜有研究。在此，本文详细描述了广翅目昆虫中成年泥蛉（泥蛉科）、鱼蛉（齿蛉科：鱼蛉亚科）和齿蛉（齿蛉科：齿蛉亚科）的排液行为，涉及该行为的发生时间及可能的功能。当受到人为干扰时，雄性和雌性昆虫均可从肛门排出液体。然而，泥蛉排出液体的频率远低于鱼蛉和齿蛉。泥蛉排出液体的量相对于体重也较小。在鱼蛉和齿蛉中，排出液体的量会随着成虫年龄的增长而减少，这可能是因为液体一旦排出就很少得到补充。这种乳白色液体似乎是在蛹期通过马氏管产生的蜕皮液，在大多数其他全变态昆虫中，这种液体通常在成虫羽化时排出。然而，成年鱼蛉和齿蛉在羽化后受到干扰时，常常会通过弯曲腹部大力排出这种液体。因此，排液可能是一种反捕食行为，尤其是在能够排出相对大量液体的较年轻成虫中。
