Laboratory studies on the olfactory behaviour of Anopheles quadriannulatus

The host preference of Anopheles quadriannulatus Theobald (Diptera: Culicidae), the zoophilic member of the malaria mosquito complex Anopheles gambiae Giles, was investigated in a dual-choice olfactometer. Naive female mosquitoes were exposed to CO2, acetone, 1-octen-3-ol, and skin emanations from cows and humans in various combinations. Their behavioural responses were recorded when they had entered one of either upwind traps from where the odours were being released. The mosquitoes did not respond to CO2 when released at human or cattle equivalent concentrations. Too few mosquitoes responded to acetone to allow for a statistical analysis. The combination of CO2+ 1-octen-3-ol was repellent. Cow odour alone was slightly attractive, but there was a synergistic attractive effect of cow odour + CO2. Surprisingly, the mosquitoes were attracted to human odour, and in a choice situation human odour was selected above cow odour + CO2. Anthropophilic An. gambiae Giles s.s. was repelled by cow odour + CO2 in contrast to An. quadriannulatus. In a choice situation, both mosquito species selected human odour above cow odour + CO2. The implications of these results are discussed in the light of recent behavioural data from the field

Diversity and role of cave-dwelling hematophagous insects in pathogen transmission in the Afrotropical region

International audienceThe progressive anthropization of caves for food resources or economic purposes increases human exposure to pathogens that naturally infect cave-dwelling animals. The presence of wild or domestic animals in the immediate surroundings of caves also may contribute to increasing the risk of emergence of such pathogens. Some zoonotic pathogens are transmitted through direct contact, but many others require arthropod vectors, such as blood-feeding insects. In Africa, hematophagous insects often play a key role in the epidemiology of many pathogens; however, their ecology in cave habitats remains poorly known. During the last decades, several investigations carried out in Afrotropical caves suggested the medical and veterinary importance particularly of insect taxa of the Diptera order. Therefore, the role of some of these insects as vectors of pathogens that infect cave-dwelling vertebrates has been studied. The present review summarizes these findings, brings insights into the diversity of cave-dwelling hematophagous Diptera and their involvement in pathogen transmission, and finally discusses new challenges and future research directions