A FORTRAN program was written that calculates composite linkage disequilibrium coefficients from genotypic data. Chi-square tests determine whether coefficients calculated for allele and locus pairs are significantly greater than zero. A subroutine is provided that partitions the variance in linkage disequilibrium into within- and between-subpopulation components. Output obtained from analysis of allozyme data collected from natural subpopulations of the house fly (Musca domestica L.) are included to illustrate features of the program.

Genomic libraries enriched for simple sequence repeats were constructed for Glossina morsitans morsitans, G. m. submorsitans, and G. m. centralis. Sixteen microsatellite markers were isolated from the libraries and evaluated on flies from natural G. m. morsitans populations and other Glossina species in the Morsitans and Palpalis species groups. The primers amplified appropriate sized DNA fragments in the Morsitans and Palpalis groups. In G. morsitans s.l., eight of 12 dinucleotide repeats and four of 12 trinucleotide repeats were polymorphic. The polymorphic loci showed a mean 7.5 ± 4.8 alleles per locus and their mean heterozygosity was 55.8 ± 7.7%. KeywordsGlossina morsitans complex; microsatellites; simple sequence repeats Tsetse flies (Diptera: Glossinidae) are exclusively haematophagous and confined to subSaharan Africa. Their medical and veterinary importance is great because they are the only vectors of African trypanosomiasis, 'sleeping sickness' in humans and nagana in cattle. In east and southern Africa, Glossina morsitans sensu lato and G. pallidipes are the most important vectors of trypanosomiasis. These species are assigned to the subgenus Glossina, the morsitans group (Leak 1998). Three allopatric subspecies of G. morsitans are recognized, G. m. morsitans (Gmm), G. m. centralis (Gmc), and G. m. submorsitans (Gms). Some genetic markers have been developed in Glossina. Allozyme polymorphism were detected and mapped in G. morsitans and G. palpalis by Gooding (1992). Krafsur & Griffiths (1997) examined isozyme variation at 31-45 loci in G. pallidipes, G. morsitans sensu lato, and G. swynnertoni. They found 23% of the loci were polymorphic, and heterozygosity was a statistically homogeneous 6.2% averaged over taxa. Isozyme loci in tsetse are inconvenient because it is difficult to obtain liquid nitrogen in Africa. DNA techniques, in contrast, allow use of alcohol preserved or dried material and provides more genetic variation. Solano et al. (1997) Amplification products were enriched for simple sequence repeat (SSR) loci by either hybridizing to probes bound to nylon membranes (MBP) after Edwards et al. (1996) or to biotinylated probes bound to magnetic beads (BP) following Kijas et al. (1994). Enriched fragments were amplified to and cloned in pGEM7 plasmids (Promega) and plated. Colonies were picked and their DNA amplified by using polymerase chain reaction (PCR). Amplified products of appropriate size were sequenced and primers designed for those loci containing repeats.G. m. morsitans DNA was used for the initial evaluations of presumptive loci for polymorphisms. Primers were also tested against DNA from G. m. centralis, G. m. submorsitans, G. pallidipes, G. swynnertoni, G. austeni, G. fuscipes, G. palpalis, G. tachinoides, G. brevipalpis, G. longipennis, and G. fuscipleuris. Genomic DNA was amplified in 10 μL reactions for 35 cycles of 94 °C for 40 s, 50 °C for 40 s, and 72 °C for 30 s. Samples were electrophoresed on 5% acrylamide gels and genotypes scored after silver staining.The M...

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.

Gene flow was studied inHarmonia axyridis(Pallas) (Coleoptera: Coccinellidae), an exotic, arboreal ladybeetle predator that recently spread rapidly throughout North America. A survey of isozyme polymorphisms showed 30 of 52 resolved putative loci were polymorphic (58%), and the mean heterozygosity was 16.75 ± 2.98% among all loci and 26.31 ± 4.37% at only the polymorphic loci. The mean number of alleles at the 52 loci was 2.01 ± 1.97. Gene frequencies were estimated in populations from Georgia, Virginia, Delaware, Rhode Island, Arkansas, Illinois, Iowa, and Oregon and differed significantly (P < 0.02) at 11 of 16 loci. Three of 16 loci (Fbp, Tre) were not in Hardy-Weinberg equilibrium in all populations and are not included in theFstatistics. Random mating was indicated within populations (FIS = −0.005 ± 0.014) but not among populations (FST = 0.025 ± 0.005). According to Wright's island model,FSTestimates the average number of reproducing immigrants to be equivalent to ca. 10 beetles per population per generation. Thus there was a measure of genetic differentiation caused by drift, but this differentiation was small with respect to the large geographical distances among the sampled populations. The genetic data suggest that the founding North American population(s) was substanti KeywordsHarmonia axyridis, isozyme variation, breeding structure, gene flow, colonizing species Gene flow was studied in Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), an exotic, arboreal ladybeetle predator that recently spread rapidly throughout North America. A survey of isozyme polymorphisms showed 30 of 52 resolved putative loci were polymorphic (58%), and the mean heterozygosity was 16.75 6 2.98% among all loci and 26.31 6 4.37% at only the polymorphic loci. The mean number of alleles at the 52 loci was 2.01 6 1.97. Gene frequencies were estimated in populations from Georgia, Virginia, Delaware, Rhode Island, Arkansas, Illinois, Iowa, and Oregon and differed significantly (P F 0.02) at 11 of 16 loci. Three of 16 loci (Fbp, Est-1, Tre) were not in Hardy-Weinberg equilibrium in all populations and are not included in the F statistics. Random mating was indicated within populations (F IS 5 20.005 6 0.014) but not among populations (F ST 5 0.025 6 0.005). According to Wright's island model, F ST estimates the average number of reproducing immigrants to be equivalent to ca. 10 beetles per population per generation. Thus there was a measure of genetic differentiation caused by drift, but this differentiation was small with respect to the large geographical distances among the sampled populations. The genetic data suggest that the founding North American population(s) was substantial. r 1997 Academic Press

Mitochondrial DNA diversity was studied at four loci in six natural populations of the tsetse fly Glossina pallidipes from Zimbabwe, Mozambique, Kenya, and Ethiopia. Single-locus diversity varied from 0.39 at 12S to 0.65 at COII. A total of 32 haplotypes was found with a mean of 6.4 +/- 2.9 per locus. To study breeding structure, diversity at two loci, COII and 16S2, was evaluated in 18 populations sampled from an area of approximately 1,611,000 km2 and in three laboratory cultures. Twenty-six haplotypes were detected at the two loci and mean haplotype diversity over all natural populations was 0.63. A high degree of population subdivision was detected within and among the Ethiopian and Kenya populations. The Zimbabwe and Zambia populations showed much less variation and differentiation than the northern populations. A population in Mozambique showed high levels of haplotype variation and affinities closest to populations in eastern Kenya, some 1700 km to the north. Analysis of variance of haplotype frequencies showed that 51.5% of the total lay within populations, 13% among populations within five nested groups, and 35.5% among the five groups. Wright's FST was 0.485, Nei's GST was 0.33, and Weir and Cunningham's theta = 0.45. Ecological data show that G. pallidipes is highly vagile. The large amount of genetic differentiation may be explained by genetic drift that occurred in scattered, relict populations during the rinderpest panzootic of the late 19th and early 20th centuries.