Wing Mite Research Articles

Isolation and characterisation of microsatellite loci for two species of Spinturnicid bat wing mites (Spinturnix myoti and Spinturnix bechsteini)

To investigate the potential for host-parasite coadaptation between bats and their wing mites, we developed microsatellite loci for two species of Spinturnix mites. For Spinturnix myoti, parasite of Myotis myotis, we were able to develop nine polymorphic loci and screened them in 100 mites from five bat colonies. For S. bechsteini, parasite of M. bechsteinii, we developed five polymorphic loci, which were also screened in 100 mites from five bat colonies. In both species, all markers were highly polymorphic (22-46 and 6-23 alleles per locus respectively). The majority of markers for both species exhibited departure from Hardy-Weinberg proportions (8 of 9 and 3 of 5, respectively). One marker pair in S. myoti showed evidence for linkage disequilibrium. As the observed departures from Hardy-Weinberg proportions are most likely a consequence of the biology of the mites, the described microsatellite loci should be useful in studying population genetics and host-parasite dynamics of Spinturnix myoti and Spinturnix bechsteini in relation to their bat hosts.

Spatio‐temporal population genetic structure of the parasitic mite Spinturnix bechsteini is shaped by its own demography and the social system of its bat host

Information about the population genetic structures of parasites is important for an understanding of parasite transmission pathways and ultimately the co-evolution with their hosts. If parasites cannot disperse independently of their hosts, a parasite's population structure will depend upon the host's spatial distribution. Geographical barriers affecting host dispersal can therefore lead to structured parasite populations. However, how the host's social system affects the genetic structure of parasite populations is largely unknown. We used mitochondrial DNA (mtDNA) to describe the spatio-temporal population structure of a contact-transmitted parasitic wing mite (Spinturnix bechsteini) and compared it to that of its social host, the Bechstein's bat (Myotis bechsteinii). We observed no genetic differentiation between mites living on different bats within a colony. This suggests that mites can move freely among bats of the same colony. As expected in case of restricted inter-colony dispersal, we observed a strong genetic differentiation of mites among demographically isolated bat colonies. In contrast, we found a strong genetic turnover between years when we investigated the temporal variation of mite haplotypes within colonies. This can be explained with mite dispersal occuring between colonies and bottlenecks of mite populations within colonies. The observed absence of isolation by distance could be the result from genetic drift and/or from mites dispersing even between remote bat colonies, whose members may meet at mating sites in autumn or in hibernacula in winter. Our data show that the population structure of this parasitic wing mite is influenced by its own demography and the peculiar social system of its bat host.

Does the mode of transmission between hosts affect the host choice strategies of parasites? Implications from a field study on bat fly and wing mite infestation of Bechstein's bats

In a two‐year field study, we analyzed the distribution of two hematophagous ectoparasites, the bat fly Basilia nana and the wing mite Spinturnix bechsteini, within and among 14 female colonies and among 26 solitary male Bechstein's bats Myotis bechsteinii. Our goal was to investigate whether differences in the transmission mode of the parasites, which result from differences in their life cycle, affect their distribution between host colonies and among host individuals within colonies. Bat flies deposit puparia in bat roosts, allowing for the transmission of hatched flies via successively shared roosts, independent of body contact between hosts or of hosts occupying a roost at the same time. In contrast, wing mites stay on the bat's body and are transmitted exclusively by contact of bats that roost together. As expected in cases of higher inter‐colony transmissibility, bat flies were more prevalent among the demographically isolated Bechstein's bat colonies and among solitary male bats, as compared to wing mites. Moreover, the prevalence and density of wing mites, but not of bat flies, was positively correlated with colony size, as expected in cases of low inter‐colony transmissibility. Within colonies, bat flies showed higher abundance on host individuals in good body condition, which are likely to have high nutritional status and strong immunity. Wing mites showed higher abundance on hosts in medium body condition and on reproductive females and juveniles, which are likely to have relatively weak immunity. We suggest that the observed infestation patterns within host colonies reflect different host choice strategies of bat flies and wing mites, which may result from differences in their inter‐colony transmissibility. Our data also indicate that infestation with wing mites, but not with bat flies, might be a cost of sociality in Bechstein's bats.

Which factors regulate the reproduction of ectoparasites of temperate-zone cave-dwelling bats?

We studied the factors which regulate the reproduction of ectoparasites of temperate-zone cave-dwelling bats, using the Schreiber's bat (Miniopterus schreibersii) and its ectoparasites as a model. For this, we searched 969 bats during 2003 and 2004 at important stages of the bat yearly cycle and found four ectoparasite species regularly occurring on them: two nycteribiids (Nycteribia schmidlii and Penicillidia conspicua), one wing mite (Spinturnix psi), and one hard tick (Ixodes simplex simplex). These parasites were present throughout the yearly cycle, but their reproductive activity greatly fluctuated seasonally. Also, we found that sex, age, and reproductive status of the host strongly influenced the reproductive activity of parasites. Overall, the four parasite species had a similar reproductive pattern, reproducing more intensively during the pregnancy and nursing seasons of M. schreibersii, mainly on pregnant and juvenile bats. Moreover, parasites greatly reduced reproductive activity during winter, while bats were in deep torpor or hibernating. We conclude that reproduction in ectoparasites of M. schreibersii and of many other temperate cave-dwelling bats is mostly regulated by the reproductive cycle of their bat hosts, but also limited by roost temperatures during winter. The fact that the reproductive cycle of parasite species of such distinct taxonomic groups are similarly adjusted to that of their bat host suggests that this adjustment is a highly adaptive trait.

Ectoparasitic Assemblages on Mormoopid Bats (Chiroptera: Mormoopidae) from Puerto Rico

We performed the first quantitative survey of ectoparasitic assemblages on three species of mormoopid bats living on the Caribbean island of Puerto Rico: Mormoops blainvillii Leach (n = 40), Pteronotus quadridens Gundlach (n = 40), and Pteronotus parnellii Gray (n = 9). We examined bats for parasites primarily on 8–10 May and 24–27 July 2002 at Culebrones Cave, near Arecibo, Puerto Rico. Only 50% of M. blainvillii were infested with at least one parasite, compared with 85–100% for Pteronotus; infested individuals of both species of Pteronotus also harbored a greater number of parasites than did M. blainvillii. The assemblage on M. blainvillii was less diverse than in the other species and more dominated by a single group of parasites, the chiggers. Chirodiscid ear mites and spinturnicid wing mites were common on both species of Pteronotus but absent from M. blainvillii. All P. parnellii harbored streblid flies, but none typically was found on P. quadridens or M. blainvillii. Adult female M. blainvillii and P. quadridens sheltered a greater number of ectoparasites than did males. All host-parasite combinations represented new associations for Puerto Rico.

Ectoparasitic Assemblages on Mormoopid Bats (Chiroptera: Mormoopidae) from Puerto Rico

We performed the first quantitative survey of ectoparasitic assemblages on three species of mormoopid bats living on the Caribbean island of Puerto Rico: Mormoops blainvillii Leach (n=40), Pteronotus quadridens Gundlach (n=40), and Pteronotus parnellii Gray (n=9). We examined bats for parasites primarily on 8-10 May and 24-27 July 2002 at Culebrones Cave, near Arecibo, Puerto Rico. Only 50% of M. blainvillii were infested with at least one parasite, compared with 85-100% for Pteronotus; infested individuals of both species of Pteronotus also harbored a greater number of parasites than did M. blainvillii. The assemblage on M. blainvillii was less diverse than in the other species and more dominated by a single group of parasites, the chiggers. Chirodiscid ear mites and spinturnicid wing mites were common on both species of Pteronotus but absent from M. blainvillii. All P. parnellii harbored streblid flies, but none typically was found on P. quadridens or M. blainvillii. Adult female M. blainvillii and P. quadridens sheltered a greater number of ectoparasites than did males. All host-parasite combinations represented new associations for Puerto Rico.

ECTOPARASITES IN AN URBAN POPULATION OF BIG BROWN BATS (EPTESICUS FUSCUS) IN COLORADO

Ectoparasites of an urban population of big brown bats (Eptesicus fuscus) in Fort Collins, Colorado, were investigated during summers 2002, 2003, and 2004. Eleven species of ectoparasites were found (the macronyssid mite Steatonyssus occidentalis, the wing mite Spinturnix bakeri, the myobiid mites Acanthophthirius caudata and Pteracarus aculeus, the chirodiscid mite Alabidocarpus eptesicus, the demodicid mite Demodex sp., the chigger Leptotrombidium myotis, the soft tick Carios kelleyi, the batfly Basilia forcipata, the batbug Cimex pilosellus, and the flea Myodopsylla borealis). Five species were analyzed by prevalence and intensity (C. pilosellus, M. borealis, L. myotis, S. bakeri, and S. occidentalis) based on 2161 counts of 1702 marked individual bats over the 3 summer study periods. We investigated 4 factors potentially influencing prevalence and intensity: age class of the host, reproductive status of adult female hosts, roosts in which the hosts were found, and abiotic conditions during the year sampled. The macronyssid mite, S. occidentalis, was the most prevalent and abundant ectoparasite. Adult big brown bats had more ectoparasites than volant juveniles for most of the species analyzed. In a sample of known age bats at 1 large colony, bats of 4 yr of age or greater had higher ectoparasite loads of S. occidentalis and S. bakeri when compared with younger bats. Lactating female bats had the highest prevalence and intensities of most ectoparasites. Annual differences in ectoparasite prevalence and intensity were related to temperature and humidity, which can affect the nidicolous species of ectoparasites. Residents of 2 buildings sprayed insecticides in response to Cimex sp., and this appeared to reduce ectoparasitism of S. occidentalis and C. pilosellus present at these buildings. Intensity of S. occidentalis had no influence on annual survival of big brown bats.

Ectoparasite associations of bats from central Pennsylvania.

Between April and October 1997, 689 bats representing seven species were captured at Pennsylvania's Canoe Creek State Park. Each bat was sampled for ectoparasitic arthropods, and four species were collected from 13.2% of the host individuals. Ectoparasites include the bat flea Myodopsylla insignis (Rothschild), the wing mite Spinturnix americanus (Banks), the bed bug Cimex adjunctus Barber, and the soft tick Ornithodoros kelleyi Cooley & Kohls. Prevalence, relative density, and mean intensity were calculated for ectoparasites of Myotis lucifugus (Le Conte), which harbored all four ectoparasite species and was the most commonly captured host. Patterns of ectoparasite associations were examined with respect to host sex and habitat (roost characteristics). Female M. lucifugus hosted higher densities of ectoparasites than did males. Moreover, relative densities of ectoparasites from M. lucifugus were dependent on the proximate roost; hosts captured near Bat Church were more heavily parasitized than those captured near Hartman Mine. Two other bat species were infested with at least one ectoparasite, but sample sizes were too small to analyze statistically. These bat species included Myotis septentrionalis (Trouessart), harboring M. insignis, S. americanus, and O. kelleyi, and Eptesicus fuscus (Beauvois), which harbored M. insignis and O. kelleyi.

Host tracking or resource tracking? the case of Periglischrus wing mites (Acarina: Spinturnicidae) of leaf-nosed bats (Chiroptera: Phyllostomidae) from Michoacán, México.

Las hipótesis de seguimiento del huesped (host tracking) versus seguimiento de recursos (resource tracking) fueron analizadas en ácaros spinturnícidos del genero Periglischrus, parásitos asociados a los murciélagos de la familia Phyllostomidae. Diferentes líneas de evidencia sugieren que estos ácaros siguen a los huespedes, es decir, que no responden a factores ambientales más alla del cuerpo de los mismos. Con una sola excepción, cada especie huesped fue infectada por una sola especie de ácaro. En algunos casos, una especie de ácaro infectó más de una especie de murciélago, pero siempre estos huespedes fueron especies estrechamente relacionadas, componiendo un grupo monofilético dentro de nuestra muestra. Por último, se usaron análisis por sistema de información geográfica (GIS) para evaluar los efectos de precipitación anual, vegetación, clima y suelos en la distribución de los ácaros dentro de la distribución de sus huespedes en Michoacán. Aquellas asociaciones con un tamaño de muestra adecuado resultaron no significativas, indicando que las distribuciones de los ácaros no varían con respecto a factores ambientales. Datos y análisis adicionales son necesarios para poner a prueba estos resultados, así como para evaluar otros factores ambientales no analizados en este estudio y que pudieran ser de importancia en la determinación de la distribución de los ácaros.