The reproduction of sand flies is dependent on the intake of vertebrate blood by females, which is used to produce eggs. The blood-feeding process involves sophisticated mechanisms of host-seeking behaviour, and may result in the transmission of Leishmania parasites, and other human and animal disease agents. A mechanistic knowledge of these processes is paramount to understand disease epidemiology, and to develop tools and strategies for monitoring and control of sand fly vectors. This chapter provides a comprehensive review of the literature on the host-seeking behaviour of phlebotomine sand flies and highlights the knowledge gaps to be addressed in future investigations. Sand fly host-seeking behaviour is triggered by intrinsic physiological mechanisms, as well as extrinsic environmental factors. Studies conducted around the world show that sand flies are attracted to carbon dioxide. Of all other volatile compounds emitted by hosts, the racemic mixture of 1-octen-3-ol elicits consistent attraction in some sand fly species under field conditions, whereas other tested host compounds elicit attraction only in laboratory experiments. Although physical cues, such as host temperature, shape and colour, are suspected to play important roles in host location, little is known about how these cues attract sand flies to particular hosts, and how they interact with chemical cues to elicit host-seeking behaviour. Despite efforts made to improve the efficiency of sand fly traps by utilising host-volatile compounds as lures, few field studies have been performed to quantify sand fly attraction to these traps. We recommend that further studies are urgently needed to identify physical cues and additional host chemicals, which attract sand flies, and determine the concentrations and distance of attraction of these cues. Knowledge from such studies will facilitate the design of traps for sand flies, and will be of great value for disease control programmes.
Keywords: kairomone, blood feeding, leishmaniasis, surveillance, zooprophylaxis
