Population genetics is a convenient tool to study the population biology of non‐model and hard to sample species. This is particularly true for parasites and vectors. Heterozygote deficits and/or linkage disequilibrium often occur in such studies and detecting the origin of those (Wahlund effect, reproductive system or amplification problems) is uneasy. We used new tools (correlation between the number of times a locus is found in significant linkage disequilibrium and its genetic diversity, correlations between Wright's FIS and FST, FIS and number of missing data, FIT and allele size and standard errors comparisons) for the first time on a real data set of tsetse flies, a vector of dangerous diseases to humans and domestic animals in sub‐Saharan Africa. With these new tools, and cleaning data from null allele, temporal heterogeneity and short allele dominance effects, we unveiled the coexistence of two highly divergent cryptic clades in the same sites. These results are in line with other studies suggesting that the biodiversity of many taxa still largely remain undescribed, in particular pathogenic agents and their vectors. Our results also advocate that including individuals from different cohorts tends to bias subdivision measures and that keeping loci with short allele dominance and/or too frequent missing data seriously jeopardize parameter's estimations. Finally, separated analyses of the two clades suggest very small tsetse densities and relatively large dispersal.

Monitoring abundance is essential for vector management, but it is often only possible in a fraction of managed areas. For vector control programmes, sampling to estimate abundance is usually carried out at a local‐scale (10s km2), while interventions often extend across 100s km2. Geostatistical models have been used to interpolate between points where data are available, but this still requires costly sampling across the entire area of interest. Instead, we used geostatistical models to predict local‐scale spatial variation in the abundance of tsetse—vectors of human and animal African trypanosomes—beyond the spatial extent of data to which models were fitted, in Serengeti, Tanzania.We sampled Glossina swynnertoni and Glossina pallidipes >10 km inside the Serengeti National Park (SNP) and along four transects extending into areas where humans and livestock live. We fitted geostatistical models to data >10 km inside the SNP to produce maps of abundance for the entire region, including unprotected areas.Inside the SNP, the mean number of G. pallidipes caught per trap per day in dense woodland was 166 (± 24 SE), compared to 3 (±1) in grassland. Glossina swynnertoni was more homogenous with respective means of 15 (±3) and 15 (±8). In general, models predicted a decline in abundance from protected to unprotected areas, related to anthropogenic changes to vegetation, which was confirmed during field survey. Synthesis and applications. Our approach allows vector control managers to identify sites predicted to have relatively high tsetse abundance, and therefore to design and implement improved surveillance strategies. In East and Southern Africa, trypanosomiasis is associated with wilderness areas. Our study identified pockets of vegetation which could sustain tsetse populations in farming areas outside the Serengeti National Park. Our method will assist countries in identifying, monitoring and, if necessary, controlling tsetse in trypanosomiasis foci. This has specific application to tsetse, but the approach could also be developed for vectors of other pathogens.

BackgroundHere we set out to standardize long-lasting, visually-attractive devices for Glossina swynnertoni, a vector of both human and animal trypanosomiasis in open savannah in Tanzania and Kenya, and in neighbouring conservation areas used by pastoralists. The goal was to determine the most practical device/material that would induce the strongest landing response in G. swynnertoni for use in area-wide population suppression of this fly with insecticide-impregnated devices.Methods and FindingsTrials were conducted in wet and dry seasons in the Serengeti and Maasai Mara to measure the performance of traps and targets of different sizes and colours, with and without chemical baits, at different population densities and under different environmental conditions. Adhesive film was used as a simple enumerator at these remote locations to compare trapping efficiencies of devices. Independent of season or presence of chemical baits, targets in phthalogen blue or turquoise blue cloth with adhesive film were the best devices for capturing G. swynnertoni in all situations, catching up to 19 times more flies than pyramidal traps. Baiting with chemicals did not affect the relative performance of devices. Fly landings were two times higher on 1 m2 blue-black targets as on pyramidal traps when equivalent areas of both were covered with adhesive film. Landings on 1 m2 blue-black targets were compared to those on smaller phthalogen blue 0.5 m2 all-blue or blue-black-blue cloth targets, and to landings on all-blue plastic 0.32–0.47 m2 leg panels painted in phthalogen blue. These smaller targets and leg panels captured equivalent numbers of G. swynnertoni per unit area as bigger targets.ConclusionsLeg panels and 0.5 m2 cloth targets show promise as cost effective devices for management of G. swynnertoni as they can be used for both control (insecticide-impregnated cloth) and for sampling (rigid plastic with insect glue or adhesive film) of populations.

In the absence of national control programmes against Rhodesian human African trypanosomiasis, farmer-led treatment of cattle with pyrethroid-based insecticides may be an effective strategy for foci at the edges of wildlife areas, but there is limited evidence to support this. We combined data on insecticide use by farmers, tsetse abundance and trypanosome prevalence, with mathematical models, to quantify the likely impact of insecticide-treated cattle. Sixteen percent of farmers reported treating cattle with a pyrethroid, and chemical analysis indicated 18% of individual cattle had been treated, in the previous week. Treatment of cattle was estimated to increase daily mortality of tsetse by 5-14%.

23In the absence of national control programmes against Rhodesian human African 24 trypanosomiasis, farmer-led treatment of cattle with pyrethroid-based insecticides may be an 25 effective strategy for foci at the edges of wildlife areas, but there is limited evidence to 26 support this. 27 We combined data on insecticide use by farmers, tsetse abundance and trypanosome 28 prevalence with mathematical models to quantify the likely impact of insecticide-treated 29 cattle. 30 Sixteen percent of farmers reported treating cattle with a pyrethroid, and chemical analysis 31 indicated 18% of individual cattle had been treated, in the previous week. Treatment of cattle 32 was estimated to increase daily mortality of tsetse by 5 -14%. Trypanosome prevalence in 33 tsetse, predominantly from wildlife areas, was 1.25% for T. brucei s.l. and 0.03% for T. b. 34 rhodesiense. For 750 cattle sampled from 48 herds, 2.3% were PCR positive for T. brucei s.l. 35 and none for T. b. rhodesiense. Using mathematical models, we estimated there was 8 -29% 36 increase in mortality of tsetse in farming areas and this increase can explain the relatively low 37 prevalence of T. brucei s.l. in cattle. 38Farmer-led treatment of cattle with pyrethroids is likely, in part, to be limiting the spill-over 39 of human-infective trypanosomes from wildlife areas. 40 41 Author summary 42 The acute form of sleeping sickness in Africa is caused by the parasite Trypanosoma brucei 43 rhodesiense. It is transmitted by tsetse flies and can be maintained in cycles involving both 44 livestock and wildlife as hosts. Humans are incidentally infected and are particularly at risk 3 45 of infection near protected areas where there are both wildlife and suitable habitat for tsetse. 46In these regions, the tsetse vector cannot be eradicated, nor can infection be prevented in 47 wildlife. Here we use field studies of tsetse and livestock in combination with mathematical 48 models of tsetse population change and trypanosome transmission to show that use of 49 pyrethroid-based insecticides on cattle by farmers at the edge of protected areas could be 50 contributing to lowering the risk of sleeping sickness in Serengeti District, Tanzania. To our 51 knowledge, our study is the first to report farmer-led tsetse control, co-incident with tsetse 52 decline and relatively low prevalence of T. brucei s.l. in cattle. 53 54 Introduction 55 In East and Southern Africa, tsetse flies (Glossina spp) transmit Trypanosoma brucei 56 rhodesiense, which causes Rhodesian human African trypanosomiasis (r-HAT). Tsetse also 57 transmit T. congolense, T. vivax and T. brucei, the causative agents of animal African 58 trypanosomiasis (AAT) in livestock. 59 Trypanosoma brucei s.l., T. congolense and T. vivax can circulate in transmission cycles 60 involving livestock or wild mammals [1]. The extensive conservation areas of East and 61 Southern Africa that support tsetse, as well as wildlife, can therefore be foci for r-HAT and 62 AAT. At the interface of wildlife-and livestock areas, ...