Human seroprevalence against Borrelia burgdorferi sensu lato in two comparable regions of the eastern Alps is not correlated to vector infection rates.

Seroprevalences were determined by testing sera of 1607 blood donors from North, East, and South Tyrol. In the Tyrols, the continental divide delimitates areas with high seroprevalences of IgG antibodies against Borrelia burgdorferi sensu lato in the North (7.2%) from areas with low seroprevalences in the South (1.5%). To determine Borrelia prevalences in unfed Ixodes ricinus ticks, 755 questing ticks were tested by PCR. Prevalences in nymphal and adult ticks were found to be 19.7% (n=132) and 21.5% (n=205) in North Tyrol and 23% (n=43) and 23.7% (n=376) in South Tyrol, respectively. Sequencing of 46 Borrelia-positive ticks yielded 74% Borrelia (B.) afzelii, 11% B. garinii, 7% B. lusitaniae, 7% B. burgdorferi sensu stricto, and 2% B. valaisiana infections. Distinct genetic clusters could not be delimitated on either side of the continental divide. This study describes occurrence and geographic dispersion of Borrelia spp. in the Tyrols, discusses possible reasons for significant differences in human seroprevalence, and indicates that prevalence of Borrelia in vector ticks is not a direct predictive factor for the local seroprevalence in humans.

Spotted fever group--Rickettsiae in the Tyrols: evidence by seroepidemiology and PCR.

The aim of our study was to assess the occurrence of Rickettsia in the inner-alpine valleys of the Eastern Alps and to determine the amount of seroreaction among the local human population. Ticks were investigated by PCR and the percentage of seropositives was determined among local blood donors by an in-house immunofluorescence assay. The local cut-off titre for screening of IgG was set at 1 : 128 with a well-characterised low-risk collective according to WHO-guidelines. Positive sera were confirmed by independent re-testing. Rickettsia is present in ticks north and south of the continental divide. Of 259 ticks investigated, 12.4% are positive for Rickettsia. Of over 1200 blood donors tested so far, 7.7% bear IgG at a titre of 1 : 128 or higher against R. helvetica. R. helvetica is present in the study area, causes immunoreaction among local residents and is associated with anamnestic erythema. Furthermore, screening with a second Spotted Fever Group Rickettsia indicates that significant parts of the Tyrolean population are exposed to a Rickettsia other than R. helvetica.

Molecular phylogeny and population structure of the codling moth (Cydia pomonella) in Central Europe: II. AFLP analysis reflects human-aided local adaptation of a global pest species.

Originally resident in southeastern Europe, the codling moth (Cydia pomonella L.) (Tortricidae) has achieved a nearly global distribution, being one of the most successful pest insect species known today. As shown in our accompanying study, mitochondrial genetic markers suggest a Pleistocenic splitting of Cydia pomonella into two refugial clades which came into secondary contact after de-glaciation. The actual distribution pattern shows, however, that Central European codling moths have experienced a geographic splitting into many strains and locally adapted populations, which is not reflected by their mitochondrial haplotype distribution. We therefore have applied, in addition to mitochondrial markers, an approach with a higher resolution potential at the population level, based on the analysis of amplification fragment length polymorphisms (AFLPs). As shown in the present study, AFLP markers elucidate the genetic structure of codling moth strains and populations from different Central European apple orchard sites. While individual genetic diversity within codling moth strains and populations was small, a high degree of genetic differentiation was observed between the analyzed strains and populations, even at a small geographic scale. One of the main factors contributing to local differentiation may be limited gene flow among adjacent codling moth populations. In addition, microclimatic, ecological, and geographic constraints also may favour the splitting of Cydia pomonella into many local populations. Lastly, codling moths in Central European fruit orchards may experience considerable selective pressure due to pest control activities. As a consequence of all these selective forces, today in Central Europe we see a patchy distribution of many locally adapted codling moth populations, each of them having its own genetic fingerprint. Because of the complete absence of any correlation between insecticide resistance and geographic or genetic distances among populations, AFLP markers do not have a prognostic value for predicting an outbreak of pesticide resistance in the field. By combining mitochondrial genetic data and AFLP analysis it was possible, however, to track the recent evolutionary history of Cydia pomonella on three different time scales: from population splitting in Pleistocene, to interbreeding of mitochondrial haplotypes in Holocene, to human-aided complete intermixing and splitting into many locally adapted populations in very recent times. The case of Cydia pomonella is reminiscent of examples of sympatric speciation and another example of a human-induced globally successful pest species.

Molecular phylogeny and population structure of the codling moth (Cydia pomonella) in Central Europe: I. Ancient clade splitting revealed by mitochondrial haplotype markers.

The codling moth (Cydia pomonella L., Tortricidae, Lepidoptera) is an important pest of pome fruit with global distribution. It has adapted successfully to different habitats by forming various ecotypes and populations, often termed strains, which differ among each other in several morphological, developmental, and physiological features. Many strains of Cydia pomonella have developed resistance against a broad range of chemically different pesticides. Obviously, pesticide-resistant strains must have a genetic basis inherent to the gene pool of codling moth populations, and this deserves our particular attention. The primary intention of the present study was to contribute novel information regarding the evolutionary phylogeny and phylogeography of codling moth populations in Central Europe. In addition, we aimed at testing the hypothesis that differential biological traits and response patterns towards pesticides in codling moth populations may be reflected at a mitochondrial DNA level. In particular, we wanted to test if pesticide resistance in codling moths is associated repeatedly and independently with more than one mitochondrial haplotype. To this end, we analyzed mitochondrial DNA and constructed phylogenetic trees based on three mitochondrial genes: cytochrome oxidase I (COI), the A+T-rich region of the control region (CR), and the nicotinamide adenine dinucleotide dehydrogenase subunit 5 (ND5). The results indicate that Central European populations of Cydia pomonella are clearly divided in two ancient clades. As shown by means of a molecular clock approach, the splitting of the two clades can be dated to a time period between the lower and middle Pleistocene, about 1.29-0.20 million years ago. It is assumed that the cyclic changes of warm and cold periods during Pleistocene may have lead to the geographic separation of codling moth populations due to glaciation, giving rise to the formation of the two separate refugial clades, as already shown for many other European animal species. Due to their inclination towards developing novel detoxification gene variants, codling moth individuals from both clades independently and multifariously may have developed pesticide resistance, and this process may be ongoing. During their more recent evolutionary history, natural events such as the gradual disappearance of climate-specific geographic barriers, as well as human-aided dispersal in recent historic times, may have allowed codling moth haplotypes from the original clades to interbreed and completely merge again, creating a globally successful insect species with a gene pool capable of responding to novel selective challenges by rapid adaptation.