A novel acoustic signalling system in mosquitoes: exploring the biophysical and neurophysiological basis for interactive behaviour in an insect

蚊子用触角来听声音，约翰斯顿150年前在触角底部发现了蚊子的听觉器官，他推测试听与交配行为有关。事实上，雄性蚊子的羽毛触角对其他蚊子的飞行音调很敏感，并被用来探测和定位雌性蚊子。因此，通过试听来检测配偶被认为是雄性的特权。雌性昆虫的触角形状更简单，但它们比任何其他昆虫都更敏感，但在吉布森和罗素发现它们也会对蚊子的飞行音调做出反应之前，人们对雌性昆虫的听觉行为一无所知。飞蚊的性选择是一种声音对话，当它们在彼此听得见的范围内(约10厘米)时，它们进入对话；每个蚊子通过改变自己的飞行音调来对对方的声音做出反应，直到音调在雄性和雌性伴侣的情况下汇聚，或者在同性伴侣的情况下急剧分化。因此，这些声学相互作用可以向个体揭示其相互作用是与同性还是异性伴侣，并可能掌握了解蚊子如何识别正确物种的配偶的关键。在我们最近的研究中，我们确立了蚊子相互交流的方式在无脊椎动物中似乎是独一无二的。蚊子不会发出和接收谨慎的叫声，而是不断地发出信号，以它们自己的翅膀节拍的形式，同时持续监测声音输入。它们敏感的信息是以某种方式编码的，二重唱中的每一只蚊子都会随着时间的推移改变其翅膀跳动的频率。为了发现这种特定性别的行为是什么，我们将使用我们为脊椎动物听力开发的先进技术，研究蚊子声音探测的生物物理学和神经生理学，描述蚊子触角探测和响应声音的方式，并发现蚊子如何利用听觉信息相互作用。蚊子拍打的翅膀发出复杂的声音，由多个谐波组成，在几毫秒的过程中，基频随机移动几赫兹。我们将绘制一只被拴住的飞行蚊子周围的声场图，看看是否有可能促进与附近蚊子的声学互动行为的特征。当一只被拴住的飞行蚊子探测到自己翅膀跳动以外的声音时，它会减少翅膀跳动频率的随机变化，并试图将自己的翅膀跳动频率与另一种声音相匹配。我们将利用这种反应来测试蚊子对声音的感官敏锐度。这些信息将被用来确定飞行音调的哪些成分会触发对其他蚊子的反应。到目前为止，我们已经发现，环境光强度和波长的变化会改变翅膀跳动的频率，温度和声级的增加会增加被拴住的蚊子的触角共振。我们将探索环境变化如何影响声音接收和飞行声音，以及传出神经元在控制JO频率调谐和灵敏度方面的可能作用。我们的基础研究将使用被拴住的蚊子，结果将用自由飞行的蚊子进行验证。我们的数据将被同化到模拟模型中，然后用于与活蚊子进行测试。当模型蚊子在活蚊子身上引起自然反应时，我们的目标就会实现。我们的研究结果将为蚊子这种非凡的交流方式提供丰富的新信息，并将扩大我们对昆虫听觉的生物物理和神经生理学特性的理解。这些发现将对整个动物界对听觉系统感兴趣的科学家以及那些参与控制蚊子的科学家具有重要意义，蚊子会将危及生命的病原体传播给人类。

Mosquitoes hear with their antennae and Johnston, who discovered the mosquito auditory organ at the base of the antenna 150 years ago, speculated that audition was involved with mating behaviour. Indeed, the plumose antennae of males are sensitive to the flight tone of other mosquitoes and are used to detect and locate females. Mate detection through audition was, therefore, thought to be the prerogative of the male. The antennae of females are simpler in form, but they are more sensitive than any other insect, yet nothing was known about the auditory behaviour of females until Gibson & Russell discovered that they also respond to mosquito flight tones. Sexual selection by flying mosquitoes is an acoustic dialogue which they enter into when they are within hearing range of each other (~ 10 cm); each responds to the sound of the other by altering their own flight tone, until the tones converge in the case of male-female couples, or dramatically diverge in the case of same-sex pairs. These acoustic interactions can, therefore, reveal to an individual whether its interaction is with a partner of the same or opposite sex, and may hold the key to understanding how mosquitoes identify mates of the right species. In our recent studies we established that mosquitoes communicate with each other in a way that appears to be unique amongst the invertebrates. Rather than emitting and receiving discreet calls, mosquitoes continuously send out a signal, in the form of their own wing beats, while continuously monitoring sound inputs. The information to which they are sensitive is encoded somehow in the way each mosquito in a duet alters its wing-beat frequency over time. To discover what this sex-specific behaviour is, we will investigate the biophysics and neurophysiology of sound detection in mosquitoes, using advanced techniques we have developed for vertebrate hearing, to characterise the way mosquito antennae detect and respond to sound and to discover how mosquitoes then use auditory information to interact with each other. The beating wings of mosquitoes produce complex sounds, made up of multiple harmonics, with the fundamental frequency randomly shifting by a few Hz over the course of a few milliseconds. We will map the sound field around a tethered flying mosquito to see if there are features that might facilitate acoustic interactive behaviour with nearby mosquitoes. When a tethered flying mosquito detects sound other than its own wing-beats, it reduces its random shifts in wing-beat frequency and tries to match its wing-beat frequency to the other sound. We will use this response to test the sensory acuity of mosquitoes to sound. This information will be used to determine which components of the flight tone trigger a response to other mosquitoes. So far, we have found that changes in ambient light intensity and wavelength alter wing-beat frequency and increases in temperature and sound levels increase the antennal resonance in tethered mosquitoes. We will explore how environmental changes influence sound reception and flight sounds, and the possible role of efferent neurones in controlling JO frequency tuning and sensitivity. Tethered mosquitoes will be used for our basic studies, and results will be verified with free-flying mosquitoes. Our data will be assimilated into simulation models, which will then be used to test against live mosquitoes. Our aims will be achieved when the model mosquito elicits natural responses in live mosquitoes. The results of our study will provide a wealth of new information about this remarkable form of communication in mosquitoes and will extend our understanding of the biophysical and neurophysiological properties of hearing in insects. The findings will be of significance to scientists interested in auditory systems throughout the animal kingdom and to those involved with the control of mosquitoes that transmit life-threatening pathogens to humans.