Recent Advancements in Studies on Chemosensory Mechanisms Underlying Detection of Semiochemicals in Dacini Fruit Flies of Economic Importance (Diptera: Tephritidae)

SIMPLE SUMMARY: Chemical information, among various environmental cues, is the most important factor for insect survival and reproduction. Insects usually rely on pheromone signals, including sex, aggregation, and alarm pheromones, in conspecific communications. For phytophagous insects, plant semiochemicals associated with insect–plant interactions profoundly affect insect behavior and physiology. Therefore, elucidation of the mechanisms underlying the perception of various chemical signals is essential to understand the adaptation of insects to their surrounding environment. Dacini fruit flies are interesting models to investigate chemosensory mechanisms because they utilize various chemical cues, such as floral fragrances in mutualistic relationships, volatiles released from host fruits, and sex pheromones in mating behaviors. Since many Dacini species are serious pests, novel insights into chemosensory mechanisms not only contribute to understanding basic principles of chemoreception, but also provide cues for the development of more effective agents for pest control. Herein, we review current knowledge on chemosensory mechanisms and related topics in Dacini fruit flies from various aspects of chemical ecology, physiology, neuroscience, and molecular biology. We also discuss future perspectives based on recent advancements in these studies. ABSTRACT: Dacini fruit flies mainly contain two genera, Bactrocera and Zeugodacus, and include many important pests of fruits and vegetables. Their life cycle is affected by various environmental cues. Among them, multiple characteristic semiochemicals have remarkable effects on their reproductive and host-finding behaviors. Notably, floral fragrances released from so-called fruit fly orchids strongly attract males of several Dacini fruit fly species. Focusing on the strong attraction of male flies to particular chemicals, natural and synthetic lures have been used for pest management. Thus, the perception of semiochemicals is important to understand environmental adaptation in Dacini fruit flies. Since next-generation sequencers are available, a large number of chemosensory-related genes have been identified in Dacini fruit flies, as well as other insects. Furthermore, recent studies have succeeded in the functional analyses of olfactory receptors in response to semiochemicals. Thus, characterization of molecular components required for chemoreception is under way. However, the mechanisms underlying chemoreception remain largely unknown. This paper reviews recent findings on peripheral mechanisms in the perception of odors in Dacini fruit flies, describing related studies in other dipteran species, mainly the model insect Drosophila melanogaster. Based on the review, important themes for future research have also been discussed.