ABSTRACT
Olfaction in insects has been intensely studied to address fundamental questions in sensory biology. It has yielded surprising answers and insights into reception of sensory stimuli, sensory coding, and the architecture and function of the neural circuits that drive behavior. Drosophila melanogaster is an experimentally tractable model organism that can teach us much about how insects use their senses of smell and taste to communicate, to find the hosts from which they feed, and to find sites for laying eggs. Drosophila is a member of the Diptera. The Diptera include flies and mosquitoes that transmit some of the most serious communicable diseases such as malaria, dengue fever, leishmaniasis, and African trypanosomiasis (sleeping sickness in humans). An understanding of how Diptera use olfactory cues to seek their hosts and to communicate with mating partners may have medical and economic impact if this knowledge can be translated to develop new technologies, or improve existing technologies, for pest control. In addition, courtship in Drosophila has emerged as a model for how chemicals are received in the sense organs and then perceived through processing in the neural circuits of the brain. Superficially simple, the interaction of flies in courtship and other behaviors-including aggression-turns out to be remarkably complex and modifiable by experience and learning. Pheromones are chemicals released by an organism to which a conspecific responds either behaviorally or physiologically. Hydrocarbons in the cuticle may be important in interindividual recognition of species and gender in many insects, and in social insects they additionally may act in recognition of colony membership, nestmates, caste, and kin (Howard and Blomquist 2005). Due to their low volatility, it is generally assumed that cuticular
6.1 Introduction .................................................................................................. 211 6.2 Olfactory Sensilla ......................................................................................... 212 6.3 Responses of Trichoid ORNs in Drosophila to Fly Odors ........................... 213 6.4 Molecular Basis of Odor Response in Trichoid Sensilla .............................. 215 6.5 Drosophila Pheromones in Courtship and Aggression ................................ 219 References .............................................................................................................. 223
hydrocarbons act on contact and are perceived through the taste organs, and recent studies have confirmed the involvement of taste in pheromone detection (Miyamoto and Amrein 2008; Montell 2009). However, using a stimulus method that mimics the proximity of two interacting insects, it was shown in Drosophila that extracts of flies stimulate the olfactory system at close range (Van der Goes van Naters and Carlson 2007). This chapter focuses on how candidate volatile pheromones in Drosophila are received by the sense organs and discusses recent advances in our understanding of how olfactory information modulates the flies’ behavior towards each other.
