Hatle John D, Grimké Faragher Sarah
Department of Biology, University of Southwestern Louisiana, Lafayette, LA 70504-2451, USA Fax:+1-318-482-5834; e-mail:
Oecologia. 1998 Jun;115(1-2):260-267. doi: 10.1007/s004420050515.
Studies on insect defenses have investigated the benefits of noxious chemicals, aposematic coloration, and even gregariousness, but little information exists on the role of slow movement (as opposed to rapid escape movement and the absence of movement). Using the chemically defended, slow-moving lubber grasshopper (Romalea guttata) and the northern leopard frog (Rana pipiens), we investigated the role of slow movement in insect defense. In a five-day experiment, frogs did not learn an aversion to lettuce-fed lubbers; we infer that endogenous deterrent chemicals are not important in lubber defense from frogs. In experiment 2, lubbers moved significantly more slowly than crickets in the presence of frogs held under beakers. In experiment 3, control (i.e., slow-moving) lubbers suffered significantly less predation than motion-induced lubbers, and frogs attacked control lubbers significantly later than they attacked motion-induced lubbers. Hence, slow movement appears to be an important component in enhancing lubber survivorship in frog encounters. This is the first demonstration that the slow movement of an␣aposematic insect increases its survival by failing to release the attack response of certain motion-oriented predators.
关于昆虫防御的研究已经探讨了有害化学物质、警戒色甚至群居性的益处，但关于缓慢移动（与快速逃避移动和静止不动相对）的作用却知之甚少。我们以具有化学防御能力、移动缓慢的蝗虫（Romalea guttata）和北美豹蛙（Rana pipiens）为研究对象，探究了缓慢移动在昆虫防御中的作用。在一项为期五天的实验中，青蛙并未对以生菜为食的蝗虫产生厌恶；我们推断内源性威慑化学物质在蝗虫抵御青蛙的过程中并不重要。在实验2中，在有倒扣烧杯罩住青蛙的情况下，蝗虫的移动速度明显比蟋蟀慢。在实验3中，对照（即移动缓慢的）蝗虫遭受的捕食显著少于因移动而受刺激的蝗虫，并且青蛙攻击对照蝗虫的时间明显晚于攻击因移动而受刺激的蝗虫。因此，缓慢移动似乎是提高蝗虫在与青蛙相遇时存活率的一个重要因素。这是首次证明具有警戒色的昆虫通过不触发某些以移动为导向的捕食者的攻击反应，其缓慢移动提高了自身的存活率。
