Is parasite load dependent on host aggregation size? The case of the greater mouse-eared bat Myotis myotis (Mammalia: Chiroptera) and its parasitic mite Spinturnix myoti (Acari: Gamasida)

Tomasz Postawa,Agnieszka Szubert-Kruszyńska

doi:10.1007/s00436-014-3826-8

Abstract

The risk of parasite infection grows with the size of host aggregations, which, in turn, may also depend on host sex and age and the quality of environmental resources. Herein, we studied the relationship between ectoparasitic infections with the wing mite (Spinturnix myoti) and the size of the breeding colonies, sex, age, and body condition index (BCI) of its host, the greater mouse-eared bat (Myotis myotis). The influence of environmental quality in the Carpathian Mountains (Poland) was also examined. We found significant differences in mite abundance and BCI between different breeding aggregations of the greater mouse-eared bat and also between the host sex/age categories. The most heavily infected bats were adult M. myotis females, while young males appeared to be the least infected. The BCI differed significantly between the sexes in young bats (males had a higher BCI than females) and also between colonies. No significant differences in the BCI were found for adult females. We did not find any relationship between the infestation rate of M. myotis, their colony size, the quality of environmental resources (percentage of forest cover around the colony), or the BCI. The prevalence of the various developmental stages of the mites did not differ between the host sex/age categories; however, differences were found in the sex ratios of deutonymphs and adult mites between adult M. myotis females. We predict that parasite load may not be dependent on colony size itself, but mainly on microclimatic factors, which are in turn directly correlated with colony size.

Highlights

The risk of parasite infection increases with the size of animal aggregation (Combes 2001; Patterson and Ruckstuhl 2013)
The aim of the present study was to investigate whether the infestation rate and the sex and age of the wing mite S. myoti are dependent on the sex, age, condition, environmental quality, and colony size of its host, M. myotis
A total of 2,270 mites were collected from bats, all belonging to the S. myoti species

Summary

Introduction

The risk of parasite infection increases with the size of animal aggregation (Combes 2001; Patterson and Ruckstuhl 2013) This pattern is widespread among birds, which form large colonies, especially during the hatching and rearing periods (Brown and Brown 1986; Rózsa et al 1996). A positive correlation between parasite infection intensity and host density has been observed in most colonial bird species (Brown and Brown 2000). This may be the result of an increased transfer of ectoparasites between hosts (mainly through horizontal transfer), which is indirectly confirmed by increased parasite infection in nonbreeding bird colonies (Blanco et al 1997).

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