In this time of edited volumes when the list of individual contributors may reach double figures, it is appropriate to question the usefulness of a volume, with such a broad scope, by a single author. The answer is simple. For years he has believed that the rather sharp distinction between fundamental and applied aspects of this discipline, has ill-served the significance of each; and has diminished the incidence of fruitful synergies. Yet the need for these was never greater, and this case may be developed by a single author with experience of each aspect. The inclusion of a Chapter on Genetic Engineering may raise some doubts, but it is enabled by the chosen title “Chemoreception”, as distinct from Chemoperception: the latter implies detection of a chemical, followed by a behavioural response. But the former broader category subsumes Chemoperception and allows for the reception of a chemical toxin so potent as to prelude a behavioural or physiological response, other than death. Accordingly, chemical toxins are a legitimate inclusion. In which event, their delivery through a GM plant is as appropriate for study as their application in a spray.

Recent research has added much to our knowledge of the nature and significance of chemoreception in insects. This text deals with both pure and applied aspects at the ecological level, and goes on to discuss the mechanisms by which insects detect and respond to chemicals at the molecular level. Throughout the text reference is made to appropriate techniques in both field and laboratory situations in order to provide an insight into the means of investigating the subject and to indicate the areas of likely future advances. Plant-insect interactions are considered in terms of plant chemical defences and of the co-evolved insect response to these. The role of pheromones is described with an account of the factors governing their synthesis and secretion. A chapter on pheromone gland morphology is also included. The electrophysiological approach is described and also the novel use of biochemical techniques to ascertain the mode of action of plant and insect-produced chemicals. Practical applications reported include the use of natural toxins in plant protections and the exploitation of pest-resistant crop varieties.

Olfaction and taste are of critical importance to insects and other animals, since vital behaviours, including mate, food and host seeking, as well as predator and toxin avoidance, are guided by chemosensory cues. Mate and habitat choice are to a large extent determined by chemical signals, and chemoreceptors contribute accordingly to pre-mating isolation barriers and speciation. In addition to fundamental physiological, ecological and evolutionary consideration, the knowledge of insect taste and especially olfaction is also of great importance to human economies, since it facilitates a more informed approach to the management of insect pests of agricultural crops and forests, and insect vectors of disease. Chemoreceptors, which bind to external chemical signals and then transform and send the sensory information to the brain, are at the core of the peripheral olfactory and gustatory system and have thus been the focus of recent research in chemical ecology. Specifically, emphasis has been placed on functional characterization of olfactory receptor genes, which are derived from three large gene families, namely the odorant receptors, gustatory receptors and ionotropic receptors. Spatial expression patterns of olfactory receptors in diverse chemosensory tissues provide information on divergent functions, with regards to ecologically relevant behaviours. On the other hand, characterization of olfactory receptor activation profiles, or “deorphanization”, provides complimentary data on the molecular range of receptivity to the fundamental unit of the olfactory sense. The aim of this Research Topic is to give an update on the breadth and depth of research currently in progress related to understanding the molecular mechanisms of insect chemoreception, with specific emphasis on the olfactory receptors.

In the study of the physiological basis of animal behavior Vince Dethier has been a pioneer, a guiding star. Although his own work has centered on the blowfly and the caterpillar, his interests and influence have spread far beyond the insects. The breadth of this impact is indicated by the contributions from colleagues and former students in this volume. These papers were originally presented at a meeting to honor Vince's 70th birthday held at the University of Massachusetts, Amherst, in May 1985. It was attended by friends and col leagues of all ages from many parts of the world. However, the picture presented by these papers is not the whole story. What it does not show is the extent of Vince's interest and influence beyond the rigorous, though friendly, atmosphere of the research laboratory. His idyllic summers in Maine have produced studies on the natural history of feeding by insects culminating in The Tent Makers, with more to come. In these studies we see his real love and, dare we say, understanding of the insect. Vince Dethier is not concerned simply with reaching the established scientist. In To Know a Fly he reaches out to those just beginning, perhaps even to those who will never begin, and provides insight both to the experimentalist's approach and to the fun of research. His sense of fun and his elegant, fluent writing have given us, too, his tongue-in-cheek fictional writings for children of all ages.

Olfaction and taste are of critical importance to insects and other animals, since vital behaviours, including mate, food and host seeking, as well as predator and toxin avoidance, are guided by chemosensory cues. Mate and habitat choice are to a large extent determined by chemical signals, and chemoreceptors contribute accordingly to pre-mating isolation barriers and speciation. In addition to fundamental physiological, ecological and evolutionary consideration, the knowledge of insect taste and especially olfaction is also of great importance to human economies, since it facilitates a more informed approach to the management of insect pests of agricultural crops and forests, and insect vectors of disease. Chemoreceptors, which bind to external chemical signals and then transform and send the sensory information to the brain, are at the core of the peripheral olfactory and gustatory system and have thus been the focus of recent research in chemical ecology. Specifically, emphasis has been placed on functional characterization of olfactory receptor genes, which are derived from three large gene families, namely the odorant receptors, gustatory receptors and ionotropic receptors. Spatial expression patterns of olfactory receptors in diverse chemosensory tissues provide information on divergent functions, with regards to ecologically relevant behaviours. On the other hand, characterization of olfactory receptor activation profiles, or "deorphanization", provides complimentary data on the molecular range of receptivity to the fundamental unit of the olfactory sense. The aim of this Research Topic is to give an update on the breadth and depth of research currently in progress related to understanding the molecular mechanisms of insect chemoreception, with specific emphasis on the olfactory receptors.

The sense of smell has an essential role in locating food, detecting predators, navigating, and communicating social information. Accordingly, the olfactory system has evolved complex repertoires of receptors to face these problems. Although the sense of taste has less far-reaching tasks, they are every bit as essential for the animals well-being, allowing it to reject toxic materials and to select nutritionally valuable food. The last decade has seen a massive advance in understanding the molecular logic of chemosensory information processing, beyond that already achieved in the rst few years following Linda Bucks discovery of odorant receptors. Shortly afterwards, the major principles of olfactory representation had been established in mammals as the one neuron/ one receptor rule and the convergence of neurons, which express the same receptor, onto individual modules in the olfactory bulb. In recent years, such studies have been extended to lower vertebrates, including shes and other phyla, i. e. , arthropods, worms, and insects, showing both the general validity of these concepts and some exceptions to the rule. In parallel, hallmarks of the molecular logic of taste sensation have been deciphered and found to differ in interesting ways from those of smell sensation.

Our objective in compiling a series of chapters on the chemical ecology of insects has been to delineate the major concepts of this discipline. The fine line between presenting a few topics in great detail or many topics in veneer has been carefully drawn, such that the book contains sufficient diversity to cover the field and a few topics in some depth. After the reader has penetrated the crust of what has been learned about chemical ecology of insects, the deficiencies in our understanding of this field should become evident. These deficiencies, to which no chapter topic is immune, indicate the youthful state of chemical ecology and the need for further investigations, especially those with potential for integrating elements that are presently isolated from each other. At the outset of this volume it becomes evident that, although we are beginning to decipher how receptor cells work, virtually nothing is known of how sensory information is coded to become relevant to the insect and to control the behavior of the insect. This problem is exacerbated by the state of our knowledge of how chemicals are distributed in nature, especially in complex habitats. And finally, we have been unable to understand the significance of orientation pathways of insects, in part because of the two previous problems: orientation seems to depend on patterns of distri bution of chemicals, the coding of these patterns by the central nervous system, and the generation of motor output based on the resulting motor commands.

V.1 - Physiology of ontogeny - biology, development, and aging; v.2 - A the and the external environment; Environment aspects; The insect and the external environment; Reaction and interaction; v.3 - The insect and the external environment. II. Reaction and interaction; The insect and the external environment. III. Locomotion; The insect and the internal environment-homeostasis-I; The insect and the internal environment. Homeostasis. II; The insect and the internal environment: homeostasis III.