Species diversity and human biting rates of malaria and dengue vectors in central and northern Benin

Malaria and dengue fever are transmitted by female mosquitoes of the Anopheles and Aedes genera, respectively. These diseases are among the most prevalent in sub-Saharan Africa, with dengue fever posing an increasingly significant threat. In this context, studying the species diversity of vectors, as well as their bionomics, including their ecological and behavioral traits, is essential for a better understanding of transmission dynamics, and for guiding appropriate vector control strategies. This study aims to characterize the species diversity and human bite rates of malaria and dengue vectors in central and northern Benin simultaneously, using a multimethod sampling approach combining larval surveys, captures on human volunteers, oviposition trap use, and pyrethrum spraying captures. Combined diurnal and nocturnal collections yielded a total of 2,337 adult mosquitoes across the five study communes. Species composition was dominated by the genera Aedes and Anopheles, with marked spatial heterogeneity among localities. The statistically significant intercommunal differences (p < 0.001) indicated a heterogeneous spatial distribution of the mosquito populations, which was further supported by the diversity indices. During larval surveys, 993 potential breeding sites were inspected, of which 51.0% were positive. In the study area, household containers such as buckets, jars, and jerry cans are the most abundant and productive breeding sites for Aedes. After emergence, 1,988 adult mosquitoes were identified, representing seven species: Aedes aegypti, Ae. albopictus, Ae. vittatus, Anopheles gambiae, Culex nebulosus, Cx. quinquefasciatus, and Cx. tigripes. Pyrethrum spray collection revealed five species and confirmed the presence of endophilic vectors, notably An. gambiae and Cx. quinquefasciatus. Analysis of biting activity revealed a pronounced circadian pattern: Aedes aegypti exhibited predominantly diurnal biting activity, whereas Anopheles gambiae showed a marked increase in nocturnal activity. The concurrent detection of Anopheles gambiae s.l. and Aedes aegypti during both daytime and nighttime, even at relatively low abundance levels, represents a noteworthy epidemiological signal suggesting a potential combined risk of malaria and dengue transmission. The multimethod approach highlights the importance of integrated entomological surveillance to anticipate emerging epidemiological dynamics and adapt vector control strategies to local ecological conditions.