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Population structure of G. pallidipes tsetse flies in Northwestern Kenya - Towards effective vector control
Winnie A Okeyo1, Sylvia Korir2, Daniel Ochieng' Gamba2
1Arthropod Biotechnology Program, Biotechnology Research Institute, Kenya Agricultural and Livestock Research Organization. P.O. Box 362-009002, Kikuyu, Kenya.
Background:
Tsetse flies are vectors of trypanosome parasites responsible for Human and Animal African Trypanosomiasis (HAT and AAT), diseases that greatly affect health and economic growth across sub-Saharan Africa. Vector control, one of the possible strategies to tackle these diseases, is most effective on genetically isolated tsetse populations. While the population genetic structure of Glossina pallidipes tsetse flies has been well studied in southern Kenya, little is known about populations in northwestern Kenya. This study investigated the presence, genetic diversity, and population structure of G. pallidipes in Turkana County in northwestern Kenya and surrounding regions.
Methods:
Tsetse fly surveys were carried out in Turkana, West Pokot, Samburu and Baringo Counties in northwestern Kenya. DNA was extracted from the legs of flies for genotyping using 11 microsatellite markers for G. pallidipes, followed by analysis using various population genetics software to evaluate the genetic diversity and population structure. DNA from gut and mouthparts was screened for trypanosomes.
Results And Discussion:
G. pallidipes were only detected in Turkana despite similar ecological conditions in adjacent counties, which is mostly semi-arid. This suggests that anthropogenic factors like habitat clearing and vector control may limit their distribution. Genetic analysis revealed high genetic diversity in Turkana populations, similar to those from the previously described cluster in eastern Kenya, indicating demographic stability in this ecosystem. Clustering analysis showed that while most Turkana samples grouped with eastern Kenyan populations, those from Northern Turkana (Oropoi) formed a distinct cluster, pointing to possible genetic isolation. Trypanosome screening identified T. vivax in 3.3% of the samples, though not indicating active transmission.
Recommendations:
The possibly genetically distinct tsetse population in Oropoi suggests limited gene flow, possibly due to geographic or ecological barriers. Further studies with expanded sampling are needed to confirm these findings and assess the boundaries of this genetic cluster beyond the Kenya-Uganda border. Integrating genetic data into surveillance and control programs will enhance the effectiveness of tsetse management strategies.
