An update on distribution models for Rhipicephalus microplus in West Africa

Area of Science:

• Veterinary Entomology
• Parasitology
• Climate Change Impact on Vector-borne Diseases

Background:

• The invasive cattle tick, Rhipicephalus microplus, has rapidly established populations in West Africa since its introduction approximately 8 years ago.
• Existing distribution maps for Rhipicephalus microplus in West Africa lack consensus, likely due to suboptimal modeling techniques.
• Accurate mapping is crucial for understanding the spread and implementing control strategies against this significant cattle pest.

Purpose of the Study:

• To re-investigate and model the potential distribution range of Rhipicephalus microplus in West Africa.
• To identify areas with high climate suitability for the establishment of viable tick populations.
• To provide an updated and validated distribution map for risk assessment and management.

Main Methods:

• Utilized a high-quality dataset of 104 farms in Benin and 13 validation farms.
• Applied advanced climate suitability modeling using Maxent software.
• Selected a subset of representative, uncorrelated climate variables for the modeling process.

Main Results:

• High climate suitability for Rhipicephalus microplus was predicted across the entire southern part of West Africa, including southern Nigeria, Benin, Togo, and Ghana.
• All of Côte d'Ivoire falls within the predicted distribution range.
• The southern rim of Burkina Faso is projected to be suitable for tick establishment, with validation confirming the predicted range.

Conclusions:

• The study provides a refined map of climate suitability for Rhipicephalus microplus in West Africa.
• Southern West Africa is identified as a high-risk zone for tick establishment and spread.
• While some ticks were found north of the predicted limit, low numbers suggest limited suitability for viable populations, though nomadic cattle movements present an alternative introduction pathway.