DNA bar-coding reveals source and patterns of <Emphasis Type="Italic">Thaumastocoris peregrinus</Emphasis> invasions in South Africa and South America

Thaumastocoris peregrinus is a recently introduced invertebrate pest of non-native Eucalyptus plantations in the Southern Hemisphere. It was first reported from South Africa in 2003 and in Argentina in 2005. Since then, populations have grown explosively and it has attained an almost ubiquitous distribution over several regions in South Africa on 26 Eucalyptus species. Here we address three key questions regarding this invasion, namely whether only one species has been introduced, whether there were single or multiple introductions into South Africa and South America and what the source of the introduction might have been. To answer these questions, bar-coding using mitochondrial DNA (COI) sequence diversity was used to characterise the populations of this insect from Australia, Argentina, Brazil, South Africa and Uruguay. Analyses revealed three cryptic species in Australia, of which only T. peregrinus is represented in South Africa and South America. Thaumastocoris peregrinus populations contained eight haplotypes, with a pairwise nucleotide distance of 0.2–0.9% from seventeen locations in Australia. Three of these haplotypes are shared with populations in South America and South Africa, but the latter regions do not share haplotypes. These data, together with the current distribution of the haplotypes and the known direction of original spread in these regions, suggest that at least three distinct introductions of the insect occurred in South Africa and South America before 2005. The two most common haplotypes in Sydney, one of which was also found in Brisbane, are shared with the non-native regions. Sydney populations of T. peregrinus, which have regularly reached outbreak levels in recent years, might thus have served as source of these three distinct introductions into other regions of the Southern Hemisphere.     

Development of <Emphasis Type="Italic">Cleruchoides noackae</Emphasis>, an egg-parasitoid of <Emphasis Type="Italic">Thaumastocoris peregrinus</Emphasis>, in eggs laid on different substrates,with different ages and post-cold storage

Cleruchoides noackae Lin and Huber (Hymenoptera: Mymaridae) is an egg parasitoid of Thaumastocoris peregrinus Carpintero and Dellapé (Hemiptera: Thaumastocoridae). The parasitism and development of C. noackae was studied in T. peregrinus eggs of different ages, laid on eucalyptus leaves or paper towel and stored at 5 °C. The emergence, sex ratio and development of C. noackae and hatched nymphs of T. peregrinus were evaluated. This parasitoid had an emergence rate higher than 60% from zero to one, one to two, and two to three-day old eggs and lower than 10% for those 3–4 and 4–5 days old. The female proportion was 78% and the egg-adult period for C. noackae was 19.5 days. The use of T. peregrinus eggs up to three days old, laid on paper towel and stored at 5 °C for 14 days did not affect the biological parameters of C. nockae and should be used for mass rearing of this parasitoid.     

Significant genetic differentiation between native and introduced silver carp (<Emphasis Type="Italic">Hypophthalmichthys molitrix</Emphasis>) inferred from mtDNA analysis

Silver carp Hypophthalmichthys molitrix (Cyprinidae) is native to China and has been introduced to over 80 countries. The extent of genetic diversity in introduced silver carp and the genetic divergence between introduced and native populations remain largely unknown. In this study, 241 silver carp sampled from three major native rivers and two non-native rivers (Mississippi River and Danube River) were analyzed using nucleotide sequences of mitochondrial COI gene and D-loop region. A total of 73 haplotypes were observed, with no haplotype found common to all the five populations and eight haplotypes shared by two to four populations. As compared with introduced populations, all native populations possess both higher haplotype diversity and higher nucleotide diversity, presumably a result of the founder effect. Significant genetic differentiation was revealed between native and introduced populations as well as among five sampled populations, suggesting strong selection pressures might have occurred in introduced populations. Collectively, this study not only provides baseline information for sustainable use of silver carp in their native country (i.e., China), but also offers first-hand genetic data for the control of silver carp in countries (e.g., the United States) where they are considered invasive.     

Geographical distribution,genetic diversity and social organization of a new European termite, <Emphasis Type="Italic">Reticulitermes urbis</Emphasis> (Isoptera: Rhinotermitidae)

Reticulitermes urbis is a recently described termite species that has probably been introduced into Western Europe where it has been found exclusively in urban areas. However, little is known about the geographic distribution and origin of R. urbis. This study was undertaken to determine whether this species was introduced from the Balkans. A parsimony network did not show any association between mtDNA haplotypes and geographic regions suggesting that western European populations were the result of human-mediated dispersion. Variation patterns of the COI and COII regions as well as microsatellites showed that the genetic diversity of Western European colonies was lower than for colonies collected in the Balkans, suggesting that the introduced populations suffered from a founder effect. As observed in the introduced populations of R. flavipes, all colonies of R. urbis had an extended-family structure with several reproductives. These results support the scenario that this termite was introduced into Western Europe.     

Spatial patterns of genetic differentiation in <Emphasis Type="Italic">Brachionus</Emphasis> <Emphasis Type="Italic">calyciflorus</Emphasis> species complex collected from East China in summer

In this study, the mtDNA COI genes of 124 individuals in Brachionus calyciflorus complex were sequenced and analyzed. Overall, 84 mtDNA haplotypes were defined, and were split into three clades by the phylogenetic trees. The divergences of COI gene sequence among the three clades ranged from 11.4 to 22.5%, indicating the occurrence of three cryptic species (cryptic species 1, cryptic species 2, and cryptic species 3). Within cryptic species 3, a remarkable degree of differentiation (F _st = 0.0947) might be attributable to habitat fragmentation, restricted gene flow, and founder effect, most probably together with local adaptation. The more shared haplotypes were observed, and a non-significant correlation existed between geographic and genetic distance, suggesting that some ancestral haplotypes might be involved in a past range expansion, and as founders give a similar distribution pattern among geographic populations. The networks were also in agreement with the pattern of genetic differentiation in B. calyciflorus species complex revealed by molecular phylogeny. The nested clade analysis suggested a slight geographic structure in the network I, network II, and the highest nesting clade levels within the network III. Under the possible effect of the Younger Dryas Event, the three cryptic species might have survived in multiple relict refugia throughout the south of China. The co-occurrence of cryptic species 2 and 3 might be found in Guangzhou and Hainan due to the possible interference of the barrier and contiguous range expansion. After the Younger Dryas Event, cryptic species 3 with high colonization ability might have arrived and colonized whole habitats at first, and reduce effective gene flow among cryptic species, thus effectively increasing persistence of founder events. Cryptic species 2 might, respectively, have expanded their ranges into Wuhu and Nanjing regions only because of the probable barrier of the Yangtze River, its weak colonization abilities and the ‘priority effects’ of cryptic species 3. Cryptic species 1 distributed exclusively in Danzhou probably failed to expand its ranges into mainland China because of small population size, weaker dispersal capacity, and the barrier of the Qiongzhou Strait.     

Polymorphism of the <Emphasis Type="Italic">cox1</Emphasis> mtDNA gene from cercarial isolates of the avian schistosome <Emphasis Type="Italic">Bilharziella polonica</Emphasis> (Trematoda: Schistosomatidae) from Belarussian lakes

We have studied the phylogeographic structure of avian schistosomes Bilharziella polonica (Trematoda: Schistosomatidae), parasites of 18 molluscs Planorbarius corneus (family Planorbidae) from three Belarussian lakes. Low nucleotide (π < 0.5%) and high haplotype (h = 85.6%) diversity of the gene encoding the cytochrome C oxidase first subunit (cox1) was found on the part of the species range studied. The phylogenetic reconstructions showed that the sample examined consists of at least two lineages of haplotypes, A and C. Haplotype diversity was somewhat higher in lineage C. The genetic divergence between these genealogical lines reached 0.55%, while the time of possible divergence was 180000–270000 years. Possible evolutionary scenarios for differentiation of the B. polonica lines and effectiveness of using cox1 for barcoding trematode populations and finding coevolutionary parasite-host relationships are discussed.     

From genetic structure to wetland conservation: a freshwater isopod <Emphasis Type="Italic">Paramphisopus palustris</Emphasis> (Phreatoicidea: Amphisopidae) from the Swan Coastal Plain,Western Australia

The freshwater isopod Paramphisopus palustris is ubiquitous and abundant in the groundwater-fed wetlands of the Swan Coastal Plain around Perth, Western Australia. Taxonomically, an additional variety (P. palustris fairbridgei) and species (P. montanus) are recognized from geographically outlying localities. Here a 486 bp fragment of cytochrome c oxidase subunit I (COI) mtDNA was sequenced in 68 individuals from 23 localities in order to evaluate the accepted taxonomy, to examine the evolutionary history of the species, and to identify lineages to prioritize conservation of wetlands already substantially modified. MtDNA showed individual populations to be largely distinct and differentiated. The 41 unique haplotypes formed seven independent, geographically defined networks. Phylogenetic analysis retrieved corresponding subclades, with three well-supported larger clades occurring (1) north of the Swan River, (2) south of the Swan River, and (3) in an area further south. A clear pattern of isolation by distance was detected suggesting an ancient serial founder event, with the pattern possibly persisting in the face of limited gene flow through priority effects. The possibility of incipient speciation, the monophyly of the recognized subspecies and the paraphyly of P. palustris with respect to P. montanus, suggest that the current taxonomy is invalid and requires re-examination. Divergences suggest a mid- to early Pliocene divergence of the major clades, with early Pliocene divergences among subclades probably driven by documented intense arid periods. Lineages are present in wetlands in geologically younger environments suggesting in situ survival and persistence. Seven Evolutionarily Significant Units were identified for the conservation of Paramphisopus, two of which are not currently represented in conservation reserves. With increased water demand and the negative impact of surrounding land-use, the current study provides a first phylogeographic assessment of conservation priorities for wetlands of the Swan Coastal Plain. Electronic supplementary material The online version of this article (doi: ) contains supplementary material which is available to authorized users. Handling editor: C. Sturmbauer     

Barriers to gene flow in common seadragons (Syngnathidae: <Emphasis Type="Italic">Phyllopteryx taeniolatus</Emphasis>)

The common seadragon is an iconic fish with presumed limited dispersal, because juveniles hatch directly from the tail of the male parent. Nothing is presently known of their phylogeographic structure, despite conservation concerns and a distribution spanning southern Australia. Here, we sequenced mitochondrial genes from 201 common seadragons in Western Australia, South Australia, Victoria, Tasmania and New South Wales. We show that common seadragon populations are highly structured geographically, and that genetic variation varies significantly. The historical Bassian Isthmus appears to have left a strong imprint on population structure. Populations east of the Bassian Isthmus are low in diversity and appear more connected than those in the west, although this is likely caused by a recent expansion from a common source after the Last Glacial Maximum. All individuals from Eden, Bicheno and Hobart are represented by only two haplotypes. Populations west of the Bassian Isthmus are more diverse, with the highest diversity indices shown by Western Australian and Spencer Gulf populations. A large sampling gap across the Great Australian Bight is yet to be resolved; the west versus east break here may be an artifact of this gap. Almost all sampled populations can be inferred to have limited gene flow among them, which has implications for recovery after local extinction. Populations thought to be in decline (Sydney, Hobart) showed low genetic diversity, which may make them vulnerable to further reductions.     

Absence of Ross River virus amongst Common brushtail possums (<Emphasis Type="Italic">Trichosurus vulpecula</Emphasis>) from metropolitan Sydney,Australia

Ross River virus (RRV) is a mosquito-transmitted Alphavirus emerging in urban centres throughout Australia. The Common brushtail possum (Trichosurus vulpecula), a native marsupial that has successfully adapted to human settlement, has been implicated as a maintenance reservoir for RRV. In the present study, RRV exposure was assessed amongst 72 urban-adapted possums from Northern Sydney and ten possums from a woodland area, remote from urbanisation. Serological screening was performed using an enzyme-linked immunosorbent assay to detect RRV antibodies in possum sera. Findings indicated that both possum populations from urban and woodland habitats were negative for the presence of RRV antibodies. Lack of exposure to RRV highlights that the host status of possums is contingent upon factors other than their abundance and proximity to human settlement. In view of the potential for climate change to favour transmission of mosquito-borne disease in Australia, identification of wildlife populations entirely absent of RRV may prove useful for monitoring the predicted spread of the virus.     

The host range and biology of <Emphasis Type="Italic">Cometaster pyrula</Emphasis>; a biocontrol agent for <Emphasis Type="Italic">Acacia nilotica</Emphasis> subsp. <Emphasis Type="Italic">indica</Emphasis> in Australia

Prickly acacia, Acacia nilotica subsp. indica (Benth.) Brenan, a major weed of the Mitchell Grass Downs of northern Queensland, Australia, has been the target of biological control projects since the 1980s. The leaf-feeding caterpillar Cometaster pyrula (Hopffer) was collected from Acacia nilotica subsp. kraussiana (Benth.) Brenan during surveys in South Africa to find suitable biological control agents, recognised as a potential agent, and shipped into a quarantine facility in Australia. Cometaster pyrula has a life cycle of approximately 2 months during which time the larvae feed voraciously and reach 6 cm in length. Female moths oviposit a mean of 339 eggs. When presented with cut foliage of 77 plant species, unfed neonates survived for 7 days on only Acacia nilotica subsp. indica and Acacia nilotica subsp. kraussiana. When unfed neonates were placed on potted plants of 14 plant species, all larvae except those on Acacia nilotica subsp. indica and Acacia nilotica subsp. kraussiana died within 10 days of placement. Cometaster pyrula was considered to be highly host specific and safe to release in Australia. Permission to release C. pyrula in Australia was obtained and the insect was first released in north Queensland in October 2004. The ecoclimatic model CLIMEX indicated that coastal Queensland was climatically suitable for this insect but that inland areas were only marginally suitable.     

Microsatellite and mitochondrial DNA variation defines island genetic reservoirs for reintroductions of an endangered Australian marsupial, <Emphasis Type="Italic">Perameles bougainville</Emphasis>

Natural populations of the endangered western barred bandicoot (Perameles bougainville) now exist on only two islands in Shark Bay, Western Australia. Our aim was to investigate genetic diversity in natural, reintroduced, and captive populations of the bandicoots and to assess the extent of divergence between the populations. The contemporary isolation of the natural populations has resulted in heterogeneity of allele frequency between the islands, which has acted to maintain a higher combined diversity than would be expected from either population on its own. These findings highlight how remnant island populations can act as genetic reservoirs to maximize diversity for reintroductions into a species former range. Although diversity is high between island populations, diversity within populations, based on six microsatellite loci, are amongst the lowest ever recorded for populations of marsupials. The mtDNA sequence data indicate that the two remaining natural populations show only minor divergence from each other, with the five haplotypes separated by just single base pairs. The reintroduced population and captive colonies show evidence for the loss of diversity related to genetic drift operating on small isolated populations.     

Genetic differentiation between populations of swimming crab <Emphasis Type="Italic">Portunus trituberculatus</Emphasis> along the coastal waters of the East China Sea

Portunus trituberculatus is a commercially important species widely spread in the East China Sea. Intraspecific variation of the mitochondrial DNA cytochrome oxidase subunit I (mtDNA COI) gene was investigated in 213 individuals from six localities (Changjiang Estuary, Shengsi Islands, Zhoushan Islands, Dongtou Islands, Dinghai Bay, and Quanzhou Bay) ranging from north (31°21′N) to south (24°55′N) coastal waters of the East China Sea. Overall, a total of 27 mtDNA haplotypes and 21 variable sites were detected in the 787 bp segment of COI gene. Analysis of mtDNA COI sequence data revealed that crabs from the six localities were characterized by moderately high haplotypic diversity (h = 0.787 ± 0.026), while sequence divergence values between haplotypes were relatively low (π = 0.00241 ± 0.00098). Each population was characterized by a single most frequent haplotype, shared among all six localities, and a small number of rare ones, typically present in only one or two individuals and representative of a specific population. However, neither the neighbor-joining tree nor the minimum spanning network (MSN) based on the haplotype data exhibited geographical patterns of the six populations. Mismatch distribution analysis of P. trituberculatus individuals sampled from the six localities suggested that sudden population expansion might have occurred in CJ and SS population that might be consistent with over-exploitation of the swimming crab. Analysis of molecular variance (AMOVA) and F _ST statistics showed that significant genetic differentiation existed among the SS, ZS, DT, DH, and QZ populations, suggesting that gene flow might be reduced, even between the geographically close sites, despite the high potential of dispersal. The possible causes of the observed genetic heterogeneity among the P. trituberculatus populations and the potential applications of the mtDNA COI marker in the artificial breeding and fisheries management are discussed. Handling editor: C. Sturmbauer     

Genetic analysis of emerald ash borer (<Emphasis Type="Italic">Agrilus planipennis</Emphasis> Fairmaire) populations in Asia and North America

Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive pest of North American ash (Fraxinus spp.) trees first discovered outside of its native range of northeastern Asia in 2002. EAB spread from its initial zone of discovery in the Detroit, Michigan and Windsor, Ontario metropolitan areas, in large part, from inadvertent human-assisted movement of infested ash materials. EAB infestations are now known in 15 US states and two Canadian provinces. The primary goal of this study was to use molecular markers to characterize the population genetic structure of EAB in its native and introduced range. This information may provide valuable insights on the geographic origin, potential host range, invasion potential, and additional biological control agents for ongoing management efforts of this destructive wood-boring beetle. EAB were collected from 17 localities in its native Asian range and from 7 localities in North America, and population structure analyzed using mtDNA gene sequences, AFLP fingerprints, and alleles at 2 microsatellite loci. Analysis of mtDNA cytochrome oxidase subunit I gene (COI; 439 bp) sequences revealed all North American individuals carry a common mtDNA haplotype also found in China and South Korea. Additional mtDNA haplotypes observed in China and South Korea differed from the common haplotype by 1–2 nucleotide substitutions and a single individual from Japan differed by 21 nucleotide changes (4.8%). Analysis using AFLP fingerprints (108 loci) indicated Asian populations were more highly variable, yet had less overall population structure, than the North American populations. North American populations appear most closely related to populations in our sample from the Chinese provinces of Hebei and Tianjin City. Further, population assignment tests assigned 88% of the individual beetles from North America to either Hebei or Tianjin City.     

Evaluation of cytochrome b mtDNA sequences in genetic diversity studies of <Emphasis Type="Italic">Channa marulius</Emphasis> (Channidae: Perciformes)

Channa marulius (Hamilton, 1822) is a commercially important freshwater fish and a potential candidate species for aquaculture. The present study evaluated partial Cytochrome b gene sequence of mtDNA for determining the genetic variation in wild populations of C. marulius. Genomic DNA extracted from C. marulius samples (n = 23) belonging to 3 distant rivers; Mahanadi, Teesta and Yamuna was analyzed. Sequencing of 307 bp Cytochrome b mtDNA fragment revealed the presence of 5 haplotypes with haplotype diversity value of 0.763 and nucleotide diversity value of 0.0128. Single population specific haplotype was observed in Mahanadi and Yamuna samples and 3 haplotypes in Teesta samples. The analysis of data demonstrated the suitability of partial Cytochrome b sequence in determining the genetic diversity in C. marulius population.     

Genetic variation among populations of the endangered fan mussel <Emphasis Type="Italic">Pinna nobilis</Emphasis> (Mollusca: Bivalvia) along the Tunisian coastline

The Mediterranean fan mussel Pinna nobilis is an endangered invertebrate due to overexploitation and habitat deterioration. In this species, two distinctive morphs, the “combed” and “straight and wide” forms, have been recorded and it is not known whether this morphometric variability is attributed to genetic or environmental factors. In this study, we used mitochondrial COI sequences to describe the genetic variability of five Pinna nobilis populations sampled along the northern, eastern, and southern Tunisian coastline, and to examine whether there is a genetic differentiation between the two forms of this species. DNA sequences of 675 bp from the mitochondrial COI gene have revealed 10 different haplotypes among 49 examined specimens. Haplotype diversity was high, ranging between 0.40441 and 0.80952, and showed a decreasing North-East gradient, which seems to be explained by the hydrogeography of the study area. The mitochondrial COI marker did not suggest a genetic distinctiveness between the two Pinna nobilis shell forms, “combed” and “straight and wide”. Although the morphometric plasticity of the fan mussel could be due to the influence of environmental factors, further genetic studies using nuclear markers are envisaged to investigate whether this differentiation is associated to gene flow restrictions.     

Discovery of <Emphasis Type="Italic">Ophiostoma tsotsi</Emphasis> on <Emphasis Type="Italic">Eucalyptus</Emphasis> wood chips in China

Ophiostoma species such as O. quercus are the most frequent causal agents of sapstain of freshly felled hardwood timber and pulpwood. Many species are regarded as economically important agents of wood degradation. The aim of this study was to identify a collection of Ophiostoma isolates, resembling O. quercus, found on stained Eucalyptus pulpwood chips in China. DNA sequences of the internal transcribed spacer regions, including the 5.8S region, of the ribosomal DNA, and parts of the β-tubulin and elongation factor-1α genes, revealed that the isolates were not O. quercus. Surprisingly, they represented O. tsotsi, a wound-infesting fungus recently described from hardwoods in Africa. In addition, sequence data from an isolate from agarwood in Vietnam, identified in a previous study as belonging to an unknown Pesotum species, were also shown to represent O. tsotsi. A high level of genetic variability was observed among isolates of both O. quercus and O. tsotsi. This was unexpected and suggests that both species have been present in Asia for a significant amount of time.     

The genetic structure of endangered indigenous populations of the amago salmon, <Emphasis Type="Italic">Oncorhynchus</Emphasis><Emphasis Type="Italic">masou</Emphasis><Emphasis Type="Italic">ishikawae</Emphasis>, in Japan

The amago salmon, Oncorhynchus masou ishikawae, is an endemic subspecies of O. masou in Japan. Owing to the extensive stocking of hatchery fish throughout Japan, indigenous populations of O. m. ishikawae are now on the verge of extinction. We examined the genetic effects of stocking hatchery fish on wild populations in the River Koza, Japan, using microsatellite and mitochondrial DNA (mtDNA) markers. For mtDNA, haplotype mt1, which is common in wild populations, was present exclusively in isolated wild populations assumed to be unaffected by previous stocking, while it was never observed in hatchery fish. Genetic diversity was much higher in wild populations in the stocked area, which shared many mtDNA haplotypes with hatchery fish, than in isolated wild populations with haplotype mt1. Pairwise F _ST estimates based on microsatellites showed significant differentiation among the isolated populations with many microsatellite loci monomorphic. Significant deviation from Hardy–Weinberg equilibrium was observed in wild populations in the area subject to stocking, where a Bayesian-based assignment test showed a high level of introgression with hatchery fish. These results suggest that wild populations with haplotype mt1, which became isolated through anthropogenic environmental change in the 1950–1960s, represent indigenous populations of O. m. ishikawae in the River Koza. They have low genetic diversity, most likely caused by genetic bottlenecks following damming and environmental deterioration, while stocking of hatchery fish over the past 30 years apparently had a large impact on the genetic structure of wild populations in the main channel of the River Koza.     

Species limits and population differentiation in New Zealand snipes (Scolopacidae: <Emphasis Type="Italic">Coenocorypha</Emphasis>)

At least four species of New Zealand snipes (Coenocorypha) became extinct following the introduction of predatory mammals, and another two species suffered massive range reductions. To investigate species limits and population differentiation in six of the seven remaining offshore populations, we assayed variation in nine microsatellite loci and 1,980 base pairs of four mitochondrial DNA (mtDNA) genes. Genetic diversity in all populations except the largest one on Adams Island in the Auckland Islands was very low in both genomes. Alleles were fixed at many microsatellite loci and for single mtDNA haplotypes, particularly in the populations in the Chathams, Snares, Antipodes and Campbell Islands. Strong population structure has developed, and Chathams and Snares Islands populations are effectively genetically isolated from one another and from the more southern island populations. Based on reciprocal monophyly of lineages and their morphological distinctiveness we recommend that three phylogenetic species should be recognized, C. pusilla in the Chatham Islands, C. huegeli in the Snares Islands and C. aucklandica in the southern islands. The populations of C. aucklandica in the Auckland Islands, Antipodes Island and Campbell Island may warrant recognition as subspecies, and all should be managed as separate conservation units.     

Comparative ontogenic analysis of <Emphasis Type="Italic">Cyclamen coum</Emphasis> Mill. and <Emphasis Type="Italic">Cyclamen kuznetzovii</Emphasis> Kotov et Czernov

Many issues of ontogeny, morphogenesis, and taxonomy of the Cyclamen genus plants remain poorly studied thus far. Data available on the species native to Crimea and the Caucasus are also contradictory. Here we studied the C. coum populations growing around the Maikop city in the Caucasus and those of C. kuznetzovii in Crimea in order to describe a particular ontogeny of these two taxa and to draw preliminary conclusions concerning their taxonomic location.     

Genetic diversity of <Emphasis Type="Italic">Bradysia difformis</Emphasis> (Sciaridae: Diptera) populations reflects movement of an invasive insect between forestry nurseries

The fungus gnat, Bradysia difformis (Sciaridae: Diptera) has recently been recorded for the first time from South Africa where it has been found in forestry nurseries. The presence of this insect in all the major forestry nurseries as the dominant and only sciarid species raises intriguing questions regarding its origin and population genetic structure. A 395 bp portion of the mitochondrial COI gene was analysed from B. difformis individuals collected from four nursery populations in South Africa and three nursery populations in Europe. Shared haplotypes between South African and European populations indicated a historical connection. South African populations showed high genetic diversity and low genetic differentiation. These patterns most likely reflect multiple and/or relatively large introductions of B. difformis into South Africa from its origin combined with subsequent and continued movement of plants between nurseries.