Contrasting Population Structures of Two Vectors of African Trypanosomoses in Burkina Faso: Consequences for Control

Abstract

BackgroundAfrican animal trypanosomosis is a major obstacle to the development of more efficient and sustainable livestock production systems in West Africa. Riverine tsetse species such as Glossina palpalis gambiensis Vanderplank and Glossina tachinoides Westwood are the major vectors. A wide variety of control tactics is available to manage these vectors, but their removal will in most cases only be sustainable if the control effort is targeting an entire tsetse population within a circumscribed area.Methodology/Principal FindingsIn the present study, genetic variation at microsatellite DNA loci was used to examine the population structure of G. p. gambiensis and G. tachinoides inhabiting four adjacent river basins in Burkina Faso, i.e. the Mouhoun, the Comoé, the Niger and the Sissili River Basins. Isolation by distance was significant for both species across river basins, and dispersal of G. tachinoides was ∼3 times higher than that of G. p. gambiensis. Thus, the data presented indicate that no strong barriers to gene flow exists between riverine tsetse populations in adjacent river basins, especially so for G. tachinoides.Conclusions/SignificanceTherefore, potential re-invasion of flies from adjacent river basins will have to be prevented by establishing buffer zones between the Mouhoun and the other river basin(s), in the framework of the PATTEC (Pan African Tsetse and Trypanosomosis Eradication Campaign) eradication project that is presently targeting the northern part of the Mouhoun River Basin. We argue that these genetic analyses should always be part of the baseline data collection before any tsetse control project is initiated.

Effect of sampling methods, effective population size and migration rate estimation in Glossina palpalis palpalis from Cameroon

“…G. p. palpalis in this Cameroon forest area then forms relatively large panmictic populations, as compared to other works on G. palpalis populations Kone et al, 2011;Ravel et al, 2007;Solano et al, 2009Solano et al, , 2010b, with substantial dispersal between neighboring subpopulations, suggesting ''suppression'' as the best strategy to be adopted for anti-vector campaigns. The establishment of physical barriers is of a great importance whatever the anti-vector strategy in this forest context, because of the ubiquity of the tsetse flies here, and their dispersal capacity.…”

“…In population genetics studies of tsetse flies using microsatellite markers, heterozygote deficits have frequently been reported Kone et al, 2010Kone et al, , 2011Mélachio et al, 2011;Ravel et al, 2007;Solano et al, 2000Solano et al, , 2009. In these studies, the use of several methods of analysis have shown that the Wahlund effect, the presence of null alleles and of short alleles dominance were probable sources of the artificial heterozygote deficits.…”

“…xerophily (Kone et al, 2010(Kone et al, , 2011. On the contrary, reproductive units seem smaller in Glossina palpalis sub-species, to the extent that samples from nearby traps belong to several different populations Kone et al, 2011;Ravel et al, 2007;Solano et al, 2000Solano et al, , 2009. Sampling individuals that belong to several and genetically different populations produces what is known as the Wahlund effect, characterized by an artificial increase in homozygosity as compared to panmictic expectations Solano et al, 2010a).…”

“…G. tachinoides population sizes seem to be relatively large with important migration rates and effective population sizes, probably due to their greater ecologic tolerance, i.e. xerophily (Kone et al, 2010(Kone et al, , 2011. On the contrary, reproductive units seem smaller in Glossina palpalis sub-species, to the extent that samples from nearby traps belong to several different populations Kone et al, 2011;Ravel et al, 2007;Solano et al, 2000Solano et al, , 2009.…”

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

“…Most populations (24 out of 37) were specifically sampled for this study using biconical traps (1-11 traps by site). Traps were set at ∼100-m intervals for a maximum period of 1 wk and with a maximum distance of 1 km between first and last traps (10). We also included in the analysis 13 previously sampled populations (9, 10).…”