Chemosensory system of tsetse flies (Diptera: Glossinidae)

Abstract

Tsetse flies are exclusively hematophagous and vectors of trypanosomes, which cause human and animal African trypanosomiasis. They are widely distributed in Africa, with 33 extant taxa and 22 species in three sub-genera. Despite a low reproductive rate, tsetse can maintain populations large enough to cause the restriction of the economic use of large areas of tropical Africa through the transmission of trypanosomiases. This success is largely due to their ability to navigate in their environments, using olfactory signals, which elicit critical behavioural phenotypes, such as attraction to hosts for blood meals, larviposition and resting sites, as well as avoidance of nonhosts, and potential predators. Understanding how the tsetse chemosensory system interacts with signals in the environment is important for understanding their biology, and also offers avenues to design approaches to manage these vectors. Olfactory and visual attraction of tsetse to humans and livestock have been exploited in the management of tsetse populations, using odour-baited traps and targets. Advances in genomics enable researchers to interrogate the molecular and physiological basis of tsetse olfaction. In vivo electrophysiological studies decode the tuning profiles of receptors to identify odorants with potential for tsetse control. Tsetse fly species are differentially distributed in riverine, savannah and forest ecologies, influencing the odour response dynamics, and host-preference evolution. A better understanding of the chemical ecology, specifically the host preference, of tsetse can provide insights into the mechanisms defining olfactory tuning that enhances the adaptation of tsetse to their respective ecologies, and provide novel avenues to control tsetse. This chapter focuses on tsetse-host interactions and chemosensory-related proteins, as well as sensillum diversity, morphology and function of the peripheral olfactory system.