We collected a total of 6207 bat flies (ten species) from 5874 sampled bats, belonging to 23 species sampled at 64 individual sites (Table 1., On-line supplementary Table S1, S2). In addition, nine more bat species did not harbor any bat flies (Eptesicus nilssoni n = 3, Hypsugo savii n = 14, Myotis davidii n = 14, Nyctalus lasiopterus n = 1, N. leisleri n = 1, Pipistrellus kuhlii n = 1, Pi. pipistrellus n = 103, Pi. pygmaeus n = 8 and Vespertilio murinus n = 190). Data from these hosts was excluded from further analysis.
Table 1
Bat host species, number of captured individuals, number of bat fly species registered and number of individual bat flies collected (*number of primary bat fly species in parenthesis).
Bat species | n | Infested | Number of bat flies | Number of bat fly species* | Prevalence (%, CI95%) | Infestation Intensity (CI95%) |
Miniopterus schreibersii | 2112 | 1355 | 3072 | 9 (2) | 64.16 (62.07–66.21) | 2.27 (2.16–2.37) |
Rhinolophus ferrumequinum | 502 | 117 | 196 | 8 (1) | 23.31 (19.68–27.26) | 1.68 (1.4–1.95) |
Myotis blythii | 389 | 225 | 496 | 8 (3) | 57.84 (52.76–62.8) | 2.2 (1.98–2.45) |
Myotis myotis | 316 | 197 | 566 | 5 (4) | 62.34 (56.75–67.7) | 2.87 (2.46–3.29) |
Myotis daubentonii | 266 | 122 | 286 | 7 (3) | 45.86 (39.76–52.06) | 2.34 (1.98–2.71) |
Myotis emarginatus | 248 | 4 | 9 | 3 (2) | 1.61 (0.44–4.08) | 2.25 (-0.76–5.26) |
Rhinolophus euryale | 247 | 141 | 348 | 4 (1) | 57.09 (50.66–63.34) | 2.47 (2.06–2.88) |
Myotis capaccinii | 199 | 151 | 809 | 6 (2) | 75.88 (69.32–81.65) | 5.36 (4.69–6.02) |
Myotis nattereri | 158 | 24 | 46 | 5 (2) | 15.19 (9.98–21.75) | 1.92 (1.26–2.57) |
Nyctalus noctula | 154 | 2 | 5 | 1 (1) | 1.3 (0.16–4.61) | 2.5 (NA) |
Rhinolophus hipposideros | 151 | 4 | 4 | 2 (1) | 2.65 (0.73–6.64) | 1 (NA) |
Barbastella barbastellus | 124 | 4 | 5 | 2 (2) | 3.23 (0.89–8.05) | 1.25 (0.45–2.05) |
Rhinolophus mehelyi | 124 | 43 | 72 | 2 (1) | 34.68 (26.36–43.75) | 1.67 (1.43–1.92) |
Myotis brandtii | 110 | 3 | 3 | 2 (2) | 2.73 (0.57–7.76) | 1 (NA) |
Myotis bechsteinii | 104 | 55 | 135 | 1 (1) | 52.88 (42.85–62.75) | 2.45 (1.93–2.98) |
Plecotus auritus | 53 | 1 | 1 | 1 (1) | 1.89 (0.05–10.07) | 1 (NA) |
Pipistrellus nathusii | 39 | 1 | 2 | 2 (2) | 2.56 (0.06–13.48) | 2 (NA) |
Myotis mystacinus | 36 | 4 | 5 | 1 (1) | 11.11 (3.11–26.06) | 1.25 (0.45–2.05) |
Rhinolophus blasii | 33 | 12 | 25 | 1 (1) | 36.36 (20.4–54.88) | 2.08 (1.21–2.96) |
Eptesicus serotinus | 30 | 2 | 2 | 2 (2) | 6.67 (0.82–22.07) | 1 (NA) |
Plecotus austriacus | 28 | 1 | 1 | 1 (1) | 3.57 (0.09–18.35) | 1 (NA) |
Myotis alcathoe | 19 | 9 | 12 | 2 (2) | 47.37 (24.45–71.14) | 1.33 (0.95–1.72) |
Myotis dasycneme | 7 | 1 | 2 | 1 (1) | 14.29 (0.36–57.87) | 2 (NA) |
Total | 5449 | 2478 | 6102 | 10 (-) | 45.47 (44.15–46.8) | 2.46 (2.37–2.56) |
In general, more female bats hosted bat flies (1251 infested from 2779 sampled, mean prevalence 45.01%, CI: 43.15–46.88, mean intensity 2.56, CI: 2.42–2.70), than males (1220 infested from 2981 sampled, prevalence 40.92%, CI: 39.15–42.71, intensity 2.35, CI: 2.22–2.47, Table 2.), with significant differences noted in the prevalence (Fisher`s Exact Test, p < 0.01), but not in mean intensity (Mann-Whitney U test, p > 0.68).
Table 2
Sexual differences in prevalence and intensity of bat fly infestation.
Bat species | Female | Male |
n | Prevalence (%) | Mean intensity | n | Prevalence (%) | Mean intensity |
Miniopterus schreibersii | 995 | 62.21 | 2.33 | 1113 | 66.04 | 2.21 |
Rhinolophus ferrumequinum | 306 | 21.9 | 1.37 | 194 | 25.26 | 2.1 |
Myotis blythii | 261 | 66.67 | 2.26 | 127 | 40.16 | 2.02 |
Myotis myotis | 212 | 67.45 | 3.07 | 101 | 50.5 | 2 |
Myotis daubentonii | 58 | 32.76 | 2.84 | 208 | 49.52 | 2.25 |
Myotis emarginatus | 148 | 2.03 | 2.33 | 100 | 1 | 2 |
Rhinolophus euryale | 134 | 56.72 | 2.55 | 111 | 57.66 | 2.36 |
Myotis capaccinii | 114 | 80.7 | 5.28 | 84 | 69.05 | 5.53 |
Myotis nattereri | 53 | 11.32 | 2.17 | 104 | 17.31 | 1.83 |
Rhinolophus hipposideros | 94 | 3.19 | 1 | 56 | 1.79 | 1 |
Rhinolophus mehelyi | 52 | 38.46 | 1.6 | 72 | 31.94 | 1.74 |
We found significant differences between male and female hosts, in the prevalence of infestation in case of three bat species. Females had higher prevalence in the case of My. myotis (Fisher`s Exact Test, p < 0.01) and My. blythii (Fisher`s Exact Test, p < 0.001), but males had significantly higher prevalence in case of My. daubentonii. No difference was noted between the respective prevalence values of other bat species’ sexes. Intensity of infestation differed significantly among sexes only in the case of Rhinolophus ferrumequinum, where males had significantly higher mean infestation values (Mann-Whitney U test, p < 0.014), while in case of My. myotis, females had significantly higher mean intensity (Mann-Whitney U test, p < 0.024, Table 2.).
The highest levels of prevalence (75.8%, CI: 69.32–81.65) were found in My. capaccinii, followed by Miniopterus schreibersii (64.2%, CI: 62.07–66.21) and My. myotis (62.3%, CI: 56.75–67.7). Highest intensity value was recorded also in the case of My. capaccinii (5.36 mean intensity, CI: 4.59–6.02, n = 169, range 1–29, see also Table 1). In the case of My. capaccinii both prevalence (Fisher`s Exact Test, p < 0.01) and the mean intensity (Mann-Whitney U test, p < 0.05) of infestation were significantly higher than in any other bat species.
2.1 Seasonality of parasitism
Bat fly prevalence and mean intensity significantly differed between the two seasons analyzed. Less bats were parasitized in spring than in autumn, with spring prevalence of 41.74% (CI: 39.3-44.21) vs. autumn prevalence of 48.91% (CI: 47.24–50.59; Fisher`s Exact Test, p < 0.001, Fig. 3–4). Similarly, mean intensity values were higher in autumn, too. These differences were also significant, with a mean intensity of 2.14 (CI: 1.97–2.31) in spring vs. 2.49 (CI: 2.38–2.6) in autumn (Mann-Whitney U test, p < 0.001). We found a sexual bias in seasonal infestation patterns, too. In case of males both prevalence and intensity differed significantly. In spring 32.34% (CI: 28.41–36.47) of males were infected, but this was 48.36% in autumn (CI: 46.19–50.52; Fisher`s Exact Test, p < 0.001). Also, males had a lower mean intensity (1.71, CI: 1.53–1.9) in spring, than in autumn (2.38, CI: 2.25–2.52, Mann-Whitney U test, p < 0.001). For female bats there was no significant seasonal difference in prevalence (spring 46.57%, CI: 43.57–49.64 vs. autumn 49.71%, CI: 47.08–52.35), while mean intensity being significantly higher in autumn (2.29, CI: 2.07–2.51 in spring vs. 2.64, CI: 2.47–2.81; Mann-Whitney U test, p < 0.01, see also Table 3).
Table 3
Seasonal differences in the prevalence and intensity of bat fly infestation of individual bat species.
Bat species | Prevalence (%) | Intensity |
Spring | Autumn | Fisher`s Exact Test | Spring | Autumn | Mann-Whitney U test |
Miniopterus schreibersii | 50.69 | 72.5 | p < 0.001 | 1.8 | 2.37 | p < 0.001 |
Myotis blythii | 67.31 | 51.33 | p < 0.01 | 2.32 | 2.06 | |
Rhinolophus ferrumequinum | 13.21 | 29.59 | p < 0.001 | 1.57 | 1.7 | |
Myotis daubentonii | 27.63 | 56.14 | p < 0.001 | 1.52 | 2.54 | p < 0.01 |
Rhinolophus hipposideros | 3.13 | 2.5 | | 1 | 1 | |
Myotis myotis | 79.25 | 55.22 | p < 0.01 | 3.05 | 2.22 | p < 0.01 |
Rhinolophus mehelyi | 21.15 | 44.29 | p < 0.01 | 1.27 | 1.84 | p < 0.01 |
Rhinolophus euryale | 66.67 | 54.59 | | 2.21 | 2.55 | |
2.2 Host specificity of bat flies
The most widespread bat flies were Penicillidia dufourii (found mostly on Myotis spp.) and Phthiridium biarticulatum (present mostly on bats of the genus Rhinolophus, see also Fig. 2). Each of these two parasites was recorded on 7 different host species and at each of the sampling sites (Table 5). Nycteribia schmidlii was collected from the most individual hosts (32.4% of all collected flies), followed by Pe. conspicua (14.4% of collected flies), both found mostly infesting Mi. schreibersii (Tables 4, 5).
Table 4
Bat species studied and their respective bat fly species collected in this study (the numbers in the parentheses represent the number of bat flies of the given species recorded on the host species).
Bat species | Primary | Secondary |
Barbastella barbastellus | Basilia italica (3) | Penicillidia dufourii (2) |
Eptesicus serotinus | | Penicillidia dufourii (1), Phthiridium biarticulatum (1) |
Miniopterus schreibersii | Nycteribia schmidlii (1791), Penicillidia conspicua (838) | Basilia nana (1), Nycteribia kolenatii (3), Nycteribia latreillii (13), Nycteribia pedicularia (81), Phthiridium biarticulatum (1), Penicillidia dufourii (123), Nycteribia vexata (1) |
Myotis alcathoe | Basilia italica (6) | Basilia nana (3) |
Myotis bechsteinii | Basilia nana (128) | |
Myotis blythii | Nycteribia latreillii (82), Nycteribia vexata (107), Penicillidia dufourii (285) | Basilia nana (2), Nycteribia kolenatii (2), Nycteribia schmidlii (2), Phthiridium biarticulatum (1), Penicillidia conspicua (2) |
Myotis brandtii | | Basilia nana (2) |
Myotis capaccinii | Nycteribia pedicularia (724), Penicillidia dufourii (76) | Nycteribia schmidlii (1), Phthiridium biarticulatum (1), Nycteribia kolenatii (3), Penicillidia conspicua (4) |
Myotis dasycneme | | Nycteribia kolenatii (2) |
Myotis daubentonii | Nycteribia kolenatii (220) | Nycteribia latreillii (11), Nycteribia pedicularia (20), Nycteribia vexata (3), Phthiridium biarticulatum (4), Penicillidia conspicua (2), Penicillidia dufourii (16) |
Myotis emarginatus | | Nycteribia kolenatii (4), Nycteribia latreillii (3), Penicillidia dufourii (1) |
Myotis myotis | Nycteribia latreillii (59), Nycteribia vexata (65), Penicillidia dufourii (148) | Basilia nana (4) |
Myotis mystacinus | Basilia italica (1) | |
Myotis nattereri | Basilia nana (33) | Basilia italica (1), Nycteribia kolenatii (1), Nycteribia vexata (10), Penicillidia dufourii (1) |
Nyctalus noctula | | Basilia nana (1), Nycteribia latreillii (4) |
Pipistrellus kuhlii | | |
Plecotus auritus | | Basilia nana (1) |
Plecotus austriacus | | Nycteribia schmidlii (1) |
Rhinolophus blasii | Phthiridium biarticulatum (25) | |
Rhinolophus euryale | Phthiridium biarticulatum (342) | Nycteribia latreillii (1), Nycteribia vexata( 4), Penicillidia conspicua (1) |
Rhinolophus ferrumequinum | Phthiridium biarticulatum (182) | Basilia nana (1), Nycteribia kolenatii (1), Nycteribia pedicularia (1), Nycteribia schmidlii (3), Nycteribia latreillii (1), Nycteribia vexata( 1), Penicillidia dufourii (2) |
Rhinolophus hipposideros | | Phthiridium biarticulatum (3), Nycteribia schmidlii (1) |
Rhinolophus mehelyi | Phthiridium biarticulatum (69) | Penicillidia conspicua (2) |
Table 5
Main characteristics of bat fly parasitism according to fly species and host-type (primary/non-primary).
Bat fly species | n | No. host species | Overall prevalence (%) | Mean intensity | Prevalence on primary hosts (%) | Mean intensity on primary host | Bat flies on secondary host (%) | Prevalence on secondary hosts (%) | Mean intensity on secondary hosts | No. potential parasite-host connections (realized secondary connections) | No. localities with bat fly presence on a secondary host, without realized presence on primary host |
Basilia italica | 18 | 4 | 4.23 | 1.29 | 7.26 | 1.31 | 5.56 | 0.66 | 1 | 28 (2) | 1 |
Basilia nana | 189 | 10 | 2.35 | 2.05 | 29.01 | 2.21 | 11.11 | 0.44 | 1.31 | 75 (5) | 3 |
Nycteribia kolenatii | 249 | 9 | 2.81 | 2.11 | 39.47 | 2.19 | 7.63 | 0.33 | 1.46 | 96 (4) | 0 |
Nycteribia latreillii | 246 | 8 | 2.84 | 2.1 | 14.04 | 2.13 | 14.23 | 0.53 | 1.94 | 111 (10) | 3 |
Nycteribia pedicularia | 826 | 4 | 5.1 | 5.26 | 66.33 | 5.48 | 12.35 | 0.87 | 4.08 | 76 (8) | 0 |
Nycteribia schmidlii | 1975 | 7 | 25.12 | 2.25 | 41.15 | 2.26 | 0.46 | 0.58 | 1.13 | 106(6) | 1 |
Nycteribia vexata | 307 | 7 | 3.53 | 2.18 | 18.58 | 2.19 | 6.51 | 0.3 | 2 | 95(3) | 0 |
Phtiridium biarticulatum | 634 | 10 | 7.65 | 2.05 | 33.33 | 2.06 | 1.74 | 0.25 | 1.38 | 129 (24) | 1 |
Penicillidia conspicua | 876 | 6 | 18.55 | 1.42 | 28.84 | 1.42 | 1.26 | 0.82 | 1.1 | 94 (4) | 0 |
Penicillidia dufourii | 782 | 11 | 10.75 | 1.66 | 39.38 | 1.75 | 20.46 | 3.31 | 1.39 | 177 (33) | 7 |
TOTAL | 6102 | 22 | | | | | 6.81 | | | - | - |
Eight bat species (R. blasii, R. euryale, R. ferrumequinum, R. mehelyi, My. alcathoe, My. bechsteinii, My. daubentonii and My. nattereri) were primary host for a single bat fly species. Two bat species (Mi. schreibersii and My. cappaccinii) were primary hosts for two flies, while other two host species (My. myotis and My. blythii) were primary hosts for three bat fly species (Table 4, on-line Supplementary Table S3). We found no difference in non-primary parasite-occurrence among bats caught in the first hour versus the last two hours of any given capture trial (1.07:0.93, nfirst=307, nlast=288), thus we consider that our dataset mirrors real-life situation and is not biased by accidental host-switches due to capture or handling.
We have found a significant correlation between the intensity of infestation on primary hosts and the prevalence of bat flies on secondary hosts (on-line Supplementary Table S3, Fig. 3a., T = 0.31, p < 0.014). Also, significant correlation was found between the number of host species present at any given roost and the prevalence on non-primary hosts recorded at that particular roost (see also Fig. 3c., T = 0.33, p < 0.011). There was a significant positive correlation between the number of potential parasite-host connections of hosts present at any given roost and the number of non-primary parasite-host connections for any given fly species, too (Fig. 3b., T = 0.27, p < 0.031). Males had significantly more non-primary parasites than females in term of prevalence (Fisher`s Exact Test, p < 0.001), however, this relationship was detected only in autumn.
The host specificity index (SI) was 96.79% overall; ranging between 92.85% (Ny. vexata) and 100% (B. nana). This index was higher in spring (97.6%) in comparison to autumn (90,6%), a difference close to significance (Fisher`s Exact Test, p = 0.056).