Mapping landscape friction to locate isolated tsetse populations that are candidates for elimination

Abstract

Tsetse flies are the cyclical vectors of deadly human and animal trypanosomes in sub-Saharan Africa. Tsetse control is a key component for the integrated management of both plagues, but local eradication successes have been limited to less than 2% of the infested area. This is attributed to either resurgence of residual populations that were omitted from the eradication campaign or reinvasion from neighboring infested areas. Here we focused on Glossina palpalis gambiensis, a riverine tsetse species representing the main vector of trypanosomoses in West Africa. We mapped landscape resistance to tsetse genetic flow, hereafter referred to as friction, to identify natural barriers that isolate tsetse populations. For this purpose, we fitted a statistical model of the genetic distance between 37 tsetse populations sampled in the region, using a set of remotely sensed environmental data as predictors. The least-cost path between these populations was then estimated using the predicted friction map. The method enabled us to avoid the subjectivity inherent in the expert-based weighting of environmental parameters. Finally, we identified potentially isolated clusters of G. p. gambiensis habitat based on a species distribution model and ranked them according to their predicted genetic distance to the main tsetse population. The methodology presented here will inform the choice on the most appropriate intervention strategies to be implemented against tsetse flies in different parts of Africa. It can also be used to control other pests and to support conservation of endangered species.area-wide integrated pest management | eradication | vector control | remote sensing | resistance surface

Climate change, cattle, and the challenge of sustainability in a telecoupled system in Africa

“…Climate change is expected to alter the ranges and virility of many globally significant diseases, e.g., malaria (Patz and Olson 2006) and dengue fever (Åström et al 2012). One such disease is African trypanosomosis (trypanosomiasis in humans), which occurs throughout sub-Saharan Africa and is deadly for both humans and animals, especially cattle (Bouyer et al 2015). In the following, we focus on how forecasted shifts in the geographic range of the disease caused by climate changes over the next half century in southern and eastern Africa might alter cattle production patterns, which has ramifications for human wellbeing and environmental sustainability.…”

Haematology of N’Dama and West African Short Horn cattle herds under natural Trypanosoma vivax challenge in Ghana

“…It is unlikely that a vaccine will become available in the foreseeable future ( Nyame et al , 2004; Vale, 2009). Control of tsetse flies, the cyclical vectors of trypanosomes in SSA, is a significant factor in managing the disease in a holistic manner ( Allsopp, 2001; Bouyer et al , 2015; Kgori et al , 2006; Leak et al , 1995; Mulla & Rickman, 1988; Vreysen et al , 2000). Nonetheless, local eradication successes have been limited to less than 2% of the infested area due to either resurgence of residual populations that were omitted from eradication campaigns or reinvasion from neighbouring infested areas ( Bouyer et al , 2015).…”

“…Control of tsetse flies, the cyclical vectors of trypanosomes in SSA, is a significant factor in managing the disease in a holistic manner ( Allsopp, 2001; Bouyer et al , 2015; Kgori et al , 2006; Leak et al , 1995; Mulla & Rickman, 1988; Vreysen et al , 2000). Nonetheless, local eradication successes have been limited to less than 2% of the infested area due to either resurgence of residual populations that were omitted from eradication campaigns or reinvasion from neighbouring infested areas ( Bouyer et al , 2015). Landscape friction maps based on tsetse fly genetic distances and remotely sensed environmental data have identified natural barriers to isolated clusters of Glossina palpalis gambiensis in West Africa ( Bouyer et al , 2015).…”

“…Nonetheless, local eradication successes have been limited to less than 2% of the infested area due to either resurgence of residual populations that were omitted from eradication campaigns or reinvasion from neighbouring infested areas ( Bouyer et al , 2015). Landscape friction maps based on tsetse fly genetic distances and remotely sensed environmental data have identified natural barriers to isolated clusters of Glossina palpalis gambiensis in West Africa ( Bouyer et al , 2015). This represents a major advance in locating and eradicating isolated tsetse populations without risk of reinvasion.…”

“…This represents a major advance in locating and eradicating isolated tsetse populations without risk of reinvasion. However, this innovation has yet to be replicated at the continental level under the auspices of the Pan African Tsetse and Trypanosomoses Eradication Campaign (PATTEC) ( Bouyer et al , 2015). …”