Fullard James H, Ratcliffe John M, Christie Christopher G
Department of Biology, University of Toronto at Mississauga, Mississauga, Canada, L5L 1C6.
J Exp Biol. 2007 Jul;210(Pt 14):2481-8. doi: 10.1242/jeb.001909.
Certain tiger moths (Arctiidae) defend themselves against bats by phonoresponding to their echolocation calls with trains of ultrasonic clicks. The dogbane tiger moth, Cycnia tenera, preferentially phonoresponds to the calls produced by attacking versus searching bats, suggesting that it either recognizes some acoustic feature of this phase of the bat's echolocation calls or that it simply reacts to their increased power as the bat closes. Here, we used a habituation/generalization paradigm to demonstrate that C. tenera responds neither to the shift in echolocation call frequencies nor to the change in pulse duration that is exhibited during the bat's attack phase unless these changes are accompanied by either an increase in duty cycle or a decrease in pulse period. To separate these features, we measured the moth's phonoresponse thresholds to pulsed stimuli with variable versus constant duty cycles and demonstrate that C. tenera is most sensitive to echolocation call periods expressed by an attacking bat. We suggest that, under natural conditions, C. tenera identifies an attacking bat by recognizing the pulse period of its echolocation calls but that this feature recognition is influenced by acoustic power and can be overridden by unnaturally intense sounds.
某些灯蛾（灯蛾科）通过用一连串超声波滴答声对蝙蝠的回声定位叫声进行发声回应来保护自己免受蝙蝠攻击。夹竹桃天蛾（Cycnia tenera）优先对攻击中的蝙蝠发出的叫声做出发声回应，而不是对搜索中的蝙蝠发出的叫声，这表明它要么识别出了蝙蝠回声定位叫声这一阶段的某些声学特征，要么只是随着蝙蝠靠近，对其叫声增强的功率做出反应。在这里，我们使用了一种习惯化/泛化范式来证明，夹竹桃天蛾既不会对回声定位叫声频率的变化做出反应，也不会对蝙蝠攻击阶段出现的脉冲持续时间的变化做出反应，除非这些变化伴随着占空比的增加或脉冲周期的减小。为了区分这些特征，我们测量了夹竹桃天蛾对具有可变与恒定占空比的脉冲刺激的发声反应阈值，并证明夹竹桃天蛾对攻击中的蝙蝠发出的回声定位叫声的周期最为敏感。我们认为，在自然条件下，夹竹桃天蛾通过识别蝙蝠回声定位叫声的脉冲周期来识别攻击中的蝙蝠，但这种特征识别会受到声学功率的影响，并且可能会被非自然的强烈声音所覆盖。
