Current distribution and bioecological characterizations of Aedes aegypti and Aedes albopictus in Brazzaville

Aedes aegypti is a mosquito that has been known in Congo for decades. It has always been involved in the transmission of some arboviruses. Ae. albopictus is an invasive species native from Asia. Its presence was reported in Congo in 2009. The proliferation of Ae. albopictus, especially in Brazzaville, in association with Ae. aegypti, have increased the risk of arbovirus transmission. The distribution and bio-ecology of these two species remain poorly studied. We undertook entomological investigations to determine the bio-ecological factors that may influence the abundance and distribution of the two species in two districts of Brazzaville. Collection of immature stages was carried out during the survey of breeding sites. In addition, adults were captured twice a day (morning and evening) during 8 collection sessions in dwellings. The results show that both species have the same distribution and share the same ecological sites. Their activity is essentially diurnal with nocturnal intrusion. They are more exophagous than endophagous. Domestic and peri-domestic sites, especially tires and water storage containers, are the most productive breeding sites. The biting activity has two peaks: one at the end of morning and the other at the end of afternoon. Both species have been observed in all areas visited and the larval index values are above WHO standards indicating a high epidemic risk. Aedes albopictus is the predominant species.