Impact of Global Warming on Black Flies Ecology: A Growing Threat to Exposed Populations in an Epidemiological Facies of Onchocerciasis in Côte d’Ivoire

Global warming may influence blackfly ecology by changing the environmental conditions that affect aquatic development and adult activity. This study assessed local bioecological conditions associated with blackfly abundance and daily biting activity in the Touba Department, northern Côte d’Ivoire. During three consecutive days in December 2023, adult female blackflies were collected using human bait and haemolysis tubes at two locations: the Bagbê River bridge and an agricultural field 10 km from the river. Microclimatic conditions and selected physicochemical properties of river water were recorded. Of 801 blackflies collected, 582 were captured at the field site and 219 at the bridge site. Morphological identification assigned 794 specimens to the savannah group and seven to the forest group of the Simulium damnosum complex. Hourly biting activity increased after noon at both sites and peaked between 3 and 4 p.m. The highest recorded hourly biting rate was 120 bites per person at the field site. Mean air temperatures were similar at the field and bridge sites, with no statistically significant difference (p = 0.917). The reported analyses indicated negative associations of turbidity and conductivity with blackfly density density (p = ˂ 0.01; R2 = - 0.859), whereas water temperature showed a positive association (p = 0.02; R2 = 0.684). These observations indicate substantial human exposure to blackfly bites during the sampling period. Continued entomological and environmental surveillance is warranted, although the findings do not establish a long-term effect of global warming or confirm ongoing parasite transmission.