据美国生活科学网站报道，科学家最新研究显示，毛毛虫可以吹口哨，发出吱吱尖叫，让掠食者鸟类望而却步。
毛毛虫并不能皱褶嘴唇吹口哨，因为它们并没有嘴唇，代替这一功能的是吹动身体两侧的通气孔。100多年前，科学家们就知道一些毛毛虫可以产生咔嚓声或者啸啸的噪音。然而，直到近期研究人员才开始用实验手段调查这些噪音是如何发出的，以及它们具有何种作用。
加拿大渥太华市卡尔顿大学神经行为研究专家杰恩-亚克(Jayne Yack)显示，丝蛾毛毛虫(学名为：Antheraea polyphemus)通过猛咬下颚产生咔嚓声。目前，她和同事们首次揭示胡桃毛毛虫(学名为：Amorpha juglandis)可从两侧发出短鸣。
使用高速摄像仪器，研究人员发现这些毛毛虫在“吹口哨”时，有意地将头部向后缩，压缩身体两侧的通气孔。不同于爬行动物、鸟类和哺乳动物，昆虫不会使用口腔进行呼吸，而是使用身体两侧的通气孔(spiracles)进行呼吸。科学家发现毛毛虫通过压迫通气孔中的气体产生口哨，从而产生啸啸的噪音。
卡尔顿大学研究员为了证实他们的观点，轻轻地将乳胶涂在毛毛虫两侧的8对通气孔，在捕捉幼体毛毛虫时，有序地揭开每对通气孔。研究结果显示，啸啸噪音是从这8对通气孔中传出来，每对通气孔产生的啸声可持续4秒，其声音频率可使鸟类和人类听到，并覆盖超声波段。
丝蛾毛毛虫发出的咔嚓声可以警告掠食者，告诫它们自己是令人讨厌的食物，但胡桃毛毛虫发出的短鸣却意味着什么呢？为了揭示其中的奥秘，亚克在加拿大皇后大学研究人员的协助下研究了黄莺(学名为：Dendroica petechia)，这种鸟类经常吞食毛毛虫，并生活在胡桃毛毛虫栖息的区域。
在研究实验中，科学家将胡桃毛毛虫放在黄莺笼子旁的树枝上，并耐心地拍摄期间发生的状况。令他们吃惊的是，当黄莺试图展开攻击时，毛毛虫发生的“口哨”使黄莺退缩畏惧，单足回跳或者快速飞离。在观测的一段时间内，黄莺展开了两次攻击，却均被吓退，而毛毛虫毫无损伤。
亚克说：“黄莺被突如其来的毛毛虫噪音所震惊，这些噪音或许不能说明胡桃毛毛虫是味道不佳的食物，但鸟儿却显然出现震惊，这是由该声音是预料之外的。”目前，这项最新研究发表在12月10日出版的《实验生物学》杂志上。（生物谷Bioon.com）
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生物谷推荐原文出处：
Journal of Experimental Biology doi: 10.1242/jeb.046805
Whistling in caterpillars (Amorpha juglandis, Bombycoidea): sound-producing mechanism and function
Veronica L. Bura1, Vanya G. Rohwer2, Paul R. Martin2 and Jayne E. Yack1,*
1 Department of Biology, Carleton University, Ottawa, ON, Canada, K1S 5B6
2 Department of Biology, Queen's University, Kingston, ON, Canada, K7L 3N6
* Author for correspondence (jyack@connect.carleton.ca)
Caterpillar defenses have been researched extensively, and, although most studies focus on visually communicated signals, little is known about the role that sounds play in defense. We report on whistling, a novel form of sound production for caterpillars and rare for insects in general. The North American walnut sphinx (Amorpha juglandis) produces whistle ‘trains’ ranging from 44 to 2060 ms in duration and comprising one to eight whistles. Sounds were categorized into three types: broadband, pure whistles and multi-harmonic plus broadband, with mean dominant frequencies at 15 kHz, 9 kHz and 22 kHz, respectively. The mechanism of sound production was determined by selectively obstructing abdominal spiracles, monitoring air flow at different spiracles using a laser vibrometer and recording body movements associated with sound production using high-speed video. Contractions of the anterior body segments always accompanied sound production, forcing air through a pair of enlarged spiracles on the eighth abdominal segment. We tested the hypothesis that sounds function in defense using simulated attacks with blunt forceps and natural attacks with an avian predator – the yellow warbler (Dendroica petechia). In simulated attacks, 94% of caterpillars responded with whistle trains that were frequently accompanied by directed thrashing but no obvious chemical defense. In predator trials, all birds readily attacked the caterpillar, eliciting whistle trains each time. Birds responded to whistling by hesitating, jumping back or diving away from the sound source. We conclude that caterpillar whistles are defensive and propose that they function specifically as acoustic ‘eye spots’ to startle predators.
Key words: sound production, caterpillar, acoustic communication, defense, Amorpha juglandis, whistle, yellow warbler
