Orientation Towards Hosts in Haematophagous Insects: An Integrative Perspective
Résumé
Introduction - Neuroethology (‘neuro' Greek; related to nerve cells, ‘ethos' Greek; habit or custom) addresses the neural basis of animal behaviour, through an evolutionary and comparative approach. Its main focus is understanding how the central nervous system translates biologically relevant stimuli into behavioural activity (Ewert, 1980). Various notions about the origins and goals of neuroethology exist (Ewert, 1980; Hoyle, 1984; Bullock, 1990; Pfluger and Menzel, 1999). However, the main questions addressed in this area of study, by means of experimental exploration, are as follows (Ewert, 1980): (1) Which sensory processes are responsible for distinguishing between behaviourally relevant and irrelevant stimuli? (2) How are signals localized in space and time? (3) How is information acquired, stored and recalled? (4) What is the neurophysiological basis for the motivation of a behavioural pattern? (5) How is behaviour coordinated and controlled by the central nervous system? (6) How is behaviour ontogeny related to neuronal mechanisms? Insect neuroethology is a well-developed field, thanks to advances in the development of several model systems. Studies on some of the major topics, such as wind-triggered escape, the recognition of acoustic signals, learning and memory and others, have provided considerable insight into how the nervous system controls adaptive behavioural responses in insects. The particular species chosen for detailed analysis in such studies include honeybees, cockroaches, crickets, flies and a few others. However, no blood-sucking insects are included in this ‘‘select'' group, even though some of them are classical models in insect physiology (e.g. Rhodnius prolixus) or the subject of intense study due to their impact on human health (mosquitoes). This does not mean that we lack information on their behaviour and neurobiology. On the contrary, important aspects of their behaviour, sensory physiology and functional neuroanatomy have been extensively studied. Nevertheless, very few studies have analysed this aspects with an integrative view in haematophagous insects.