Preliminary Inventory of Stomoxys spp., Potential Vectors of Pathogens in the Minkébé Forest Massif in the North-East of Gabon

Abstract

Aims: This study aims to characterize Stomoxys spp., potential vectors of pathogens in the north-east of Gabon. Place and Duration of Study: This research was conducted in the Minkébé forest massif, Woleu-Ntem Province, Gabon from April to May 2023 (rainy season). Methodology: The daily captures were conducted at Mikouka, Massoko and Minkébé using Vavoua and Nzi traps. All captured specimens were morphologically identified to species using binocular microscope (Leica Microsystems ©). The identification was aided by “specific” taxonomic keys. The collected data were organized from Microsoft Office Excel 2013. This database was used to calculate numbers and proportions of specimens observed by species. Several parameters including Apparent Density per Trap per day (ADT), Shannon, Simpson, Pielou and Bray-Curtis indices were evaluated. Results: A total of 1552 Stomoxys were caught, including 610 at Massoko, 533 at Mikouka and 409 at Minkébé. These specimens belonged to two species: Stomoxys niger niger and Stomoxys omega. Stomoxys niger niger was the most abundant with 1176 specimens caught and an ADT of 4 Stomoxys/trap/day (s/p/d). On the other hand, Stomoxys omega was poorly captured (n= 376; ADT= 1.28). As for the biotopes surveyed, Massoko (n= 619; ADT= 6.42) and Mikouka (n= 533; ADT= 5.44) were the most infested with Stomoxys spp. However, the lowest catches were recorded at Minkébé (n= 409; ADT= 4.17). The Shannon, Pielou and Simpson index values indicate relatively low levels of diversity between sites. The Shannon index reached higher values at Minkébé than at the other study sites. The Simpson and Pielou indices also had higher values at Minkébé. As for the Bray-Curtis index, its values were low between Minkébé and Mikouka (0.592), between Mikouka and Massoko (0.302) and between Minkébé and Massoko (0.384). Conclusion: Our findings show the coexistence of Stomoxys niger niger and Stomoxys omega in Minkébé. Their presence constitutes a health risk, because these vectors could play a role in the circulation of certain pathogens in the Minkébé forest massif. So, a longitudinal study of these vectors and a screening of their infectious agents are urgently needed.