The origins of extant G. pallidipes Austen (Diptera: Glossinidae) populations in the ecologically well studied Lambwe and Nguruman valleys in Kenya are controversial because populations have recovered after seemingly effective attempts to achieve high levels of control. We investigated microgeographic breeding structure of the tsetse fly, Glossina pallidipes (Diptera: Glossinidae) by analyzing spatial and temporal variation at eight microsatellite loci to test hypotheses about endemism and immigration. Samples were obtained at seasonal intervals from trap sites separated by 200 m to 14 km and arranged into blocks. G. pallidipes populations nearest to Lambwe and Nguruman also were sampled. Spatial analysis indicated genetic differentiation by genetic drift was much less among trapping sites within Lambwe and Nguruman (F ST ≤ 0.049) than between them (F ST = 0.232). F ST between Serengeti and Nguruman was 0.16 and F ST between Kodera Forest and Lambwe was 0.15. The genetic variance in G. pallidipes explained by dry and wet seasons (0.33%) was about one-fifth the variance among collection dates (1.6%) thereby indicating reasonable temporal stability of genetic variation. Gene frequencies in Kodera and Serengeti differed greatly from Lambwe and Nguruman thereby falsifying the hypothesis that Lambwe and Nguruman were repopulated by immigrants. Harmonic mean effective (= breeding) population sizes were 180 in Lambwe and 551 in Nguruman. The genetic data suggest G. pallidipes in Lambwe and Nguruman have been endemic for long intervals.

Tsetse flies are confined to sub-Saharan Africa where they occupy discontinuous habitats. In anticipation of area-wide control programmes, estimates of gene flow among tsetse populations are necessary. Genetic diversities were partitioned at eight microsatellite loci and five mitochondrial loci in 21 Glossina pallidipes Austin populations. At microsatellite loci, Nei's unbiased gene diversity averaged over loci was 0.659 and the total number of alleles was 214, only four of which were shared among all populations. The mean number of alleles per locus was 26.8. Random mating was observed within but not among populations (fixation index F ST = 0.18) and 81% of the genetic variance was within populations. Thirty-nine mitochondrial variants were detected. Mitochondrial diversities in populations varied from 0 to 0.85 and averaged 0.42, and F ST = 0.51. High levels of genetic differentiation were characteristic, extending even to subpopulations separated by tens and hundreds of kilometres, and indicating low rates of gene flow.

Single-strand conformation polymorphisms at 16S2 and COII mitochondrial genes were surveyed in 111 housefly samples from North, Central, and South America, Europe, Asia, Africa, and the Western Pacific. Forty-eight phenotypes were detected, of which none were ubiquitous, and 21 (44%) were confined to a single zoogeographical region. Nei's gene diversity index (H(S)) was 0.27 and was heterogeneous among zoogeographical regions. Phenotypes were the most diverse in the Ethiopian region and least diverse in the Palearctic and Nearctic regions. Hierarchical partitioning of the total diversity among regions (Nei's G(RT) = 0.49) indicated only a small proportion was shared. The differentiation of populations within regions (G(SR)) was 0.32. All pairwise estimates of gene flow between zoogeographical regions were less than 0.31 reproducing females per generation (mean 0.19). We conclude that housefly populations are highly structured even though the flies are mobile and easily capable of passive transport by ship and air.

Genetic diversity and differentiation within and among nine G. morsitans morsitans populations from East and southern Africa was assessed by examining variation at seven microsatellite loci and a mitochondrial locus, cytochrome oxidase (COI). Mean COI diversity within populations was 0.63+/-0.33 and 0.81 taken over all populations. Diversities averaged over microsatellite loci were high (mean number of alleles/locus>or=7.4; mean HE>or=65%) in all populations. Diversities averaged across populations were greater in East Africa (mean number of alleles=22+/-2.6; mean he=0.773+/-0.033) than in southern Africa (mean number of alleles=18.7+/-4.0; mean he=0.713+/-0.072). Differentiation among all populations was highly significant (RST=0.25, FST=0.132). Nei's Gij statistics were 0.09 and 0.19 within regions for microsatellites and mitochondria, respectively; between regions, Gij was 0.14 for microsatellites and 0.23 for mitochondria. GST among populations was 0.23 for microsatellite loci and 0.40 for mitochondria. The F, G and R statistics indicate highly restricted gene flow among G. m. morsitans populations separated over geographic scales of 12-917 km.

Glossina fuscipes fuscipes Newstead 1910 (Diptera: Glossinidae) is the primary vector of human sleeping sickness in Kenya and Uganda. This is the first report on its population structure. A total of 688 nucleotides of mitochondrial ribosomal 16S2 and cytochrome oxidase I genes were sequenced. Twenty-one variants were scored in 79 flies from three geographically diverse natural populations. Four haplotypes were shared among populations, eight were private and nine were singletons. The mean haplotype and nucleotide diversities were 0.84 and 0.009, respectively. All populations were genetically differentiated and were at demographic equilibrium. In addition, a longstanding laboratory culture originating from the Central African Republic (CAR-lab) in 1986 (or before) was examined. Haplotype and nucleotide diversities in this culture were 0.95 and 0.012, respectively. None of its 27 haplotypes were shared with the East African populations. A first approximation of relative effective population sizes was Uganda > CAR-lab > Kenya. It was concluded that the structure of G. f. fuscipes populations in East Africa is localized.