Population genetics as a tool to elucidate pathogen reservoirs: Lessons from Pseudogymnoascus destructans , the causative agent of White‐Nose disease in bats

International audienceEmerging infectious diseases pose a major threat to human, animal, and plant health. The risk of species-extinctions increases when pathogens can survive in the absence of the host. Environmental reservoirs can facilitate this. However, identifying such reservoirs and modes of infection is often highly challenging. In this study, we investigated the presence and nature of an environmental reservoir for the ascomycete fungus Pseudogymnoascus destructans, the causative agent of White-Nose disease. Using 18 microsatellite markers, we determined the genotypic differentiation between 1497 P. destructans isolates collected from nine closely situated underground sites where bats hibernate (i.e., hibernacula) in Northeastern Germany. This approach was unique in that it ensured that every isolate and resulting multilocus genotype was not only present, but also viable and therefore theoretically capable of infecting a bat. The distinct distribution of multilocus genotypes across hibernacula demonstrates that each hibernaculum has an essentially unique fungal population. This would be expected if bats become infected in their hibernaculum (i.e., the site they spend winter in to hibernate) rather than in other sites visited before they start hibernating. In one hibernaculum, both the walls and the hibernating bats were sampled at regular intervals over five consecutive winter seasons (1062 isolates), revealing higher genotypic richness on walls compared to bats and a stable frequency of multilocus genotypes over multiple winters. This clearly implicates hibernacula walls as the main environmental reservoir of the pathogen, from which bats become reinfected annually during the autumn

Habitat preferences of male Corn Buntings Emberiza calandra in north-eastern Germany

Agricultural ecosystems have faced dramatic changes during past decades, resulting in a dramatic loss of farmland biodiversity. The Corn Bunting Emberiza calandra is considered a suitable indicator for the conservation value of farmland habitats, and has recently suffered strong declines throughout much of its European range. As a basis for targeted conservation measures, we investigated the habitat preferences of this species in north-eastern Germany by comparing the composition of male territories with randomly chosen control sites. A territory was defined as the area within a radius of 150 meters around the assumed centre of the territory, as the majority of nests is found within this radius. To assess food availability for nestlings, arthropod abundance within the most abundant land use types i.e. crop fields, fallows, grassland as well as within unploughed strips was investigated. In total we found 102 male Corn Bunting territories, which were mainly composed of crop fields (50%), grassland (28%), and fallows (12%). Territories compared with control sites were characterized by a lower proportion of crop fields, a higher proportion of fallows, more diverse land use types, more abundant field boundaries, unploughed strips, and tracks, and a higher availability of song posts. However, neither the number of larger (>= 1 cm), smaller ( 10%) and song posts (> 70 m 'linear song posts' or > 1 solitary post per ha) for the habitat selection of male Corn Buntings. We conclude that measures to halt population declines of Corn Buntings seem to be relatively easy to implement, provided that farmers are granted a fair compensation

Mating type determination within a microsatellite multiplex for the fungal pathogen Pseudogymnoascus destructans, the causative agent of white-nose disease in bats

Emerging infectious diseases are a severe conservation threat for a variety of plants and animals. In North America, several bat species are threatened by white-nose disease, which has caused an unprecedented mass mortality of \u3e 6 million bats since 2006. The fungus Pseudogymnoascus (Geomyces) destructans is the causative agent of the disease. Though asexual reproduction is the norm, sexual reproduction is possible as two mating types exist. Sexual reproduction has been implicated in the emergence of virulent strains of fungi but to date no rapid means of mating type characterisation was available for P. destructans. In this study, three mating type-specific primer sets were designed and tested on 80 isolates. The primers were multiplexed with microsatellite loci allowing for rapid and concurrent genotyping and mating type assignment. These markers will have great utility in better understanding and predicting the population dynamics and evolutionary potential of this fungus, including the emergence of virulent strains