Infracommunities of bat flies (Diptera: Streblidae and Nycteribiidae) of bats (Mammalia: Chiroptera) in three conservation units in the State of Amapá, Brazil

Seasonal variation and host sex affect bat-bat fly interaction networks in the Amazonian savannahs

Bats are the second-most diverse group of mammals in the world, and bat flies are their main parasites. However, significant knowledge gaps remain regarding these antagonistic interactions, especially since diverse factors such as seasonality and host sex can affect their network structures. Here, we explore the influence of such factors by comparing species richness and composition of bat flies on host bats, as well as specialization and modularity of bat-bat fly interaction networks between seasons and adult host sexes. We captured bats and collected their ectoparasitic flies at 10 sampling sites in the savannahs of Amapá State, northeastern region of the Brazilian Amazon. Despite female bats being more parasitized and recording greater bat fly species richness in the wet season, neither relationship was statistically significant. The pooled network could be divided into 15 compartments with 54 links, and all subnetworks comprised >12 compartments. The total number of links ranged from 27 to 48 (for the dry and wet seasons, respectively), and female and male subnetworks had 44 and 41 links, respectively. Connectance values were very low for the pooled network and for all subnetworks. Our results revealed higher bat fly species richness and abundance in the wet season, whereas specialization and modularity were higher in the dry season. Moreover, the subnetwork for female bats displayed higher specialization and modularity than the male subnetwork. Therefore, both seasonality and host sex contribute in different ways to bat-bat fly network structure. Future studies should consider these factors when evaluating bat-bat fly interaction networks.

Bats (Mammalia, Chiroptera) and bat flies (Diptera, Streblidae) from the Cazumbá-Iracema and Chico Mendes Reserve, Western Brazilian Amazon

Bats belong to the order Chiroptera and are composed of 18 families, 202 genera, and 1420 species. Cosmopolitans, they have a high diversity of trophic and behavioral guilds, several ecosystem services, and intraspecific associations with ectoparasites. In Brazil, 68 species of Streblidae have already been recorded, although knowledge about the bat fauna and their ectoparasites is still low. Thus, the objective was to present a list of bat species, and to relate parasites with hosts, for two extractive reserves in the state of Acre, western Brazilian Amazon. The collections took place in ten nights, five in each RESEX, both carried out in August 2019. At each point, 10 mist nets (9 m × 2.5 m) were used, remaining open for 6 h. The captured bats were stored in cotton bags and had their data collected. Subsequently, the search for ectoparasites was carried out throughout the individual's body and extracted with brushes moistened with 96% ethyl alcohol and fine-tipped tweezers. Species of flies were identified to the lowest taxonomic level through specific bibliography. Thirty-three bats from six trophic guilds and 46 ectoparasitic dipterans were sampled, all from the Streblidae family. The most abundant bat family was Phyllostomidae, a recurring result in several studies carried out in the neotropical region. This is related to the selectivity of the mist net in bat sampling, in addition to a close correlation between Phyllostomidae bats and ectoparasitic flies of the Streblidae family.

Ectoparasitic flies of bats (Mammalia: Chiroptera) in urban green areas of northeastern Brazil

In urban and degraded areas, ectoparasite abundance can be affected by increasing human population density and habitat fragmentation. This study aimed to characterize the ectoparasitic fly community associated with bats in the urban green areas of Sergipe, Brazil. Campaigns were conducted monthly, for two consecutive nights, between September 2019 and February 2021. To capture the bats, ten mist nets were set up inside and at the edge of the habitat fragments. All ectoparasites found were removed from the bats and stored in 70% alcohol. The specificity index, parasitological rates, and level of parasite aggregation were calculated, and the influence of host sex and seasonality on parasitological rates were verified for the most parasitized bats. The collected ectoparasites corresponded to the families Nycteribiidae (S = 1; n = 26) and Streblidae (S = 13; n = 849), with Trichobius costalimai and Medistopoda aranea being the most abundant species. For some interactions, there was an influence of host sex on the prevalence rates, with the highest number of parasites being found on females, which can be explained by their greater susceptibility to parasitism owing to their long stay in roosts. The seasonality influenced the parasitological rates, and opposing patterns (from what was expected) were observed for some interactions; this influence may be due to the biological differences between parasite species. This study provides relevant data on this interaction, especially for urban areas in northeastern Brazil, expanding the number of studies in the State of Sergipe and promoting future studies.

Bat-ectoparasitic fly relationships in a seasonally dry tropical forest in Brazil

Bat ectoparasitic flies are hematophagous insects highly specialized to parasitize only bats. Knowledge about how biotic and abiotic factors can influence ecological relationships between parasites and hosts is in general incipient. Large information gaps are even worst in biodiversity-rich, but poorly sampled areas like Brazil's Caatinga, the largest tropical dry forest in South America. We used bats and their highly specialized ectoparasitic flies as a study model to clarify some aspects of this host-parasite system in this semiarid environment. We conducted fieldwork at 55 sites in the Caatinga, between April 2017 and March 2020 and collected 1300 flies (19 species) on 333 bats (15 species). Bat ectoparasitic flies were highly host-specific, had an aggregated distribution, frequently formed infracommunities with only one species, and had a male-biased sex ratio. Except for the prevalence of the streblid fly Strebla guajiro on Carollia perspicillata, which was significantly higher in the rainy season, bat flies showed no preference - expressed by frequency and intensity of infestation - for host sex, and their interspecific relationships were not mediated by rainfall. Other variables that could potentially be interfering in this host-parasite relationship deserve further attention, especially in environments such as the Caatinga where there is great seasonal variation. Furthermore, the existence of species-specific responses must be taken into account.