Modelling the Abundances of Two Major Culicoides (Diptera: Ceratopogonidae) Species in the Niayes Area of Senegal.
Authors: Diarra Maryam, Fall Moussa, Lancelot Renaud, Diop Aliou, Fall Assane G, Dicko Ahmadou, Seck Momar Talla, Garros Claire, Allène Xavier, Rakotoarivony Ignace, Bakhoum Mame Thierno, Bouyer Jérémy, Guis Hélène
Journal: PloS one
Summary
# Editorial Summary: Culicoides Vector Dynamics in Senegal The 2007 African horse sickness outbreak in Senegal caused devastating equine losses, highlighting the need to understand transmission risk from *Culicoides oxystoma* and *Culicoides imicola*, the primary suspected vectors in the region. Researchers conducted year-round monthly sampling across five sites in the Niayes area using OVI light traps, capturing over 220,000 midges and applying cross-correlation analysis to identify which environmental variables best predicted midge abundance at various time-lags. Temperature, humidity, and water body coverage emerged as key drivers for both species, though the relationships differed: *C. oxystoma* abundance was influenced by same-day temperature and humidity plus lagged humidity (19–21 days prior) and ruminant density, whilst *C. imicola* responded more directly to rainfall and vegetation index alongside water availability. These findings suggest that practitioners and epidemiologists can use local weather patterns and landscape features to forecast vector population peaks, potentially enabling targeted disease prevention strategies such as stabling during high-risk periods; however, the models' persistent overdispersion indicates that additional environmental variables and alternative trapping methods warrant investigation to refine predictions for field application.
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Practical Takeaways
- •Monitor relative humidity and temperature trends 2-3 weeks ahead as predictive indicators for Culicoides population peaks and AHS/bluetongue risk in Senegal
- •Water body proximity within 2 km radius is a key environmental risk factor; manage drainage and water management in high-risk equine areas
- •Vector abundance forecasting requires site-specific modelling rather than generic predictions, as local environmental heterogeneity drives significant variation in Culicoides populations
Key Findings
- •C. oxystoma and C. imicola abundance in Senegal is primarily driven by temperature, humidity, and water body proximity rather than single climatic variables alone
- •Mean humidity 19-21 days prior to capture significantly predicted C. oxystoma abundance, suggesting delayed environmental effects on vector populations
- •Culicoides counts showed extreme overdispersion requiring nested mixed-effect models with random effects at both site and date levels to achieve adequate fit