No abstract

Summary1. An 8-year-field experiment on moorland in northern England manipulated the abundance of legally controllable predators whilst maintaining consistent habitat conditions. Subsequent changes in both the breeding success and abundance of five ground-nesting bird species were monitored: lapwing Vanellus vanellus, golden plover Pluvialis apricaria, curlew Numenius arquata, red grouse Lagopus lagopus scoticus and meadow pipit Anthus pratensis and the abundance only of snipe Gallinago gallinago and skylark Alauda arvensis. 2. Control of fox Vulpes vulpes, carrion crow Corvus corone, stoat Mustela ermina and weasel Mustela nivalis reduced the abundance of fox ()43%) and crow ()78%); no changes were detected in already low stoat or weasel abundances. 3. Reductions in foxes and crows led to an average threefold increase in breeding success of lapwing, golden plover, curlew, red grouse and meadow pipit. 4. Predator control led to subsequent increases in breeding numbers ( ‡14% per annum) of lapwing, curlew, golden plover and red grouse, all of which declined in the absence of predator control ( ‡17% per annum). 5. Synthesis and applications. Controlling predators is a potentially important management tool for conserving a range of threatened species. Considerable sums of public monies are currently spent on habitat improvement for conservation and some of these public funds should be used to underpin habitat works with predator removal.

The genetic diversity of Borrelia burgdorferi sensu lato was assessed in a focus of Lyme borreliosis in southern Britain dominated by game birds. Ticks, rodents, and pheasants were analyzed for spirochete infections by PCR targeting the 23S-5S rRNA genes, followed by genotyping by the reverse line blot method. In questingIxodes ricinus ticks, three genospecies of B. burgdorferi sensu lato were detected, with the highest prevalences found for Borrelia garinii and Borrelia valaisiana. B. burgdorferi sensu stricto was rare (<1%) in all tick stages. Borrelia afzelii was not detected in any of the samples. More than 50% of engorged nymphs collected from pheasants were infected with borreliae, mainly B. garinii and/orB. valaisiana. Although 19% of the rodents harboredB. burgdorferi sensu stricto and/or B. gariniiin internal organs, only B. burgdorferi sensu stricto was transmitted to xenodiagnostic tick larvae (it was transmitted to 1% of the larvae). The data indicate that different genospecies of B. burgdorferi sensu lato can be maintained in nature by distinct transmission cycles involving the same vector tick species but different vertebrate host species. Wildlife management may have an influence on the relative risk of different clinical forms of Lyme borreliosis.

The abilities of the most common European genospecies of Borrelia burgdorferi sensu lato to survive blood meals taken by ticks feeding on birds were analyzed. A pattern of differential survival of the spirochetes in feeding ticks was observed. The result is consistent with the concept of selective transmission of Lyme borreliosis spirochetes.The genospecies of Borrelia burgdorferi sensu lato and, at times, their variants are maintained in nature by different sets of hosts (1, 3, 6-10, 15, 18, 20, 21, 23; K. Hanincová, S. M. Schäfer, S. Etti, H.-S. Sewell, V. Taragelová, D. Ziak, M. Labuda, and K. Kurtenbach, submitted for publication). At present, the key determinant of this host association is considered to be the interaction of B. burgdorferi sensu lato with the alternative pathway of the host's complement system (14,16,19,22,25). A recently proposed model of transmission predicts the selection of spirochetes by complement in the gut of feeding ticks (17,18). In the present study, an avian model was used to test this prediction.Two-week-old pheasants (Phasianus colchicus) were obtained from a breeder in Oxfordshire, United Kingdom. Ixodes ricinus larvae and nymphs were derived from a tick colony maintained at the NERC Centre for Ecology and Hydrology, Oxford, United Kingdom. Low-passage cultures of B. burgdorferi sensu stricto (ZS 7), Borrelia afzelii (ACA 1), Borrelia garinii (an isolate from Freiburg, Germany, with an ospA allele identical to that of the Rio2 strain [2]), and Borrelia valaisiana (strain UK) were expanded to a concentration of 10 7 cells per ml of culture medium. The cultures were used to infect questing nymphs with spirochetes by glass capillary feeding. Of those ticks which took up more than 100 spirochetes, as calculated by the volume of culture imbibed, 20 were introduced to each bird by being confined within a neoprene cell glued with latex to the shaved throat of each bird (Fig.1). Four groups composed of four birds each were challenged with ticks infected with one of the genospecies of B. burgdorferi sensu lato. Engorged nymphs were recovered, kept for 2 weeks, and then preserved in 70% ethanol.For comparison, an additional four groups of 10 nymphs each (all of whom were preinfected with one of the four genospecies) were not allowed to feed on hosts but were starved for several weeks and then preserved in ethanol. Four weeks after the challenge with infected nymphs, the pheasants were tested by xenodiagnosis for Borrelia through the introduction of Ͼ50 noninfected I. ricinus larvae per animal. These larvae were also contained in neoprene cells and glued to the back of the neck of each pheasant. Engorged larvae were allowed to molt to nymphs. After xenodiagnosis, two skin biopsy samples were taken from each bird, one from the feeding site of ticks and one from the eyelid. The 5S-23S intergenic spacer and the ospA locus of B. burgdorferi sensu lato were amplified by nested PCR from DNA extracted from Borrelia cultures, ticks, and biopsy samples (5, 15), and the PCR products were sequence...