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.

A Five-Year Study on Infestation and Abundance of Bat Flies (Hippoboscoidea: Streblidae) Under Severe Dry Season Conditions in the Tropical Dry Forest of Yucatan, Mexico

In Mexico, few studies have explored how environmental conditions in tropical dry forests (TDF) influence bat fly load even though, according to climate change scenarios, this ecosystem will experience a drier and warmer climate. Such an extension of the dry season in these ecosystems could have dramatic consequences for biodiversity, particularly in regions with plains where animals do not have elevational climate shifts. The present study therefore evaluates the effect of prevailing environmental conditions during 2015-2019, as well as host body conditions, on the infestation and abundance of bat-specific ectoparasites and the composition and bat fly load in the dry season of a TDF in Yucatan. Since Yucatan has an essentially flat and low-lying topography, organisms cannot escape from the predicted extreme conditions with elevational shifts. This region is therefore an excellent location for assessment of the potential effects of warming. We collected 270 bat flies from 12 species. Three streblid species (Nycterophilia parnelli Wenzel, Trichobius johnsonae Wenzel, and Trichobius sparsus Kessel) are new records for Yucatan. Our overview of the dry season bat ectoparasite loads reveals low values of richness and prevalence, but high aggregation. Our models detected significant differences in ectoparasite infestation and abundance over the years, but the environmental and body host condition variables were unrelated to these. We report that pregnant females are parasitized to a greater extent by bat flies during the dry season, which generally represents the season of most significant nutritional stress.

Exploring the relationship between bats (Mammalia, Chiroptera) and ectoparasitic flies (Diptera, Hippoboscoidea) of the Orinoquia Region in South America

Bat flies (Nycteribiidae and Streblidae) have been used to study co-evolutionary patterns between ectoparasites and bats. In the world, Nycteribiidae and Streblidae are represented by approximately 276 and 237 species, respectively. In regions such as the Orinoquia located in the north of South America (Colombia and Venezuela), the richness of bats is high (more than 100 documented species), but studies on Nycteribiidae and Streblidae are scarce and discontinuous. To contribute to the knowledge of ectoparasitic flies in the Orinoquia, records of flies and their interactions with bats were reviewed, including new records and associations using interaction networks. We documented 124 species of Streblidae and only 12 of Nycteribiidae for the Orinoquia in approximately 102 bat species reported in Colombia and Venezuela. New records for six species of bat flies in Colombia were found (Mastopteraguimaraesi, Noctiliostreblamaai, Paradyschiriaparvuloides, Trichobiusjubatus, Trichobiusparasiticus, and Basiliaferrisi) associated with six species of bats (Cynomopsplanirostris, Desmodusrotundus, Myotishandleyi, Molossusrufus, Noctilioalbiventris, and Phyllostomushastatus). The bat-ectoparasite interaction networks in the Orinoquia revealed a pattern of antagonistic relationships, with high specialization, modularity, and low connectivity and nesting. The identified networks are between bat fly species belonging to different ecomorphological groups with unique host species. This supports the idea of ecological niche partitioning among ectoparasitic bat flies and hosts. Our study expanded the knowledge of the distribution of some fly species and the associations with bat hosts in Colombia, by presenting morphological descriptions and new observations, which are key to understanding the ecology, diversity, and distribution of these species.

Network and parasitological analyses reveal latitudinal gradient in bats-ectoparasitic fly interactions across the Neotropic

Ecological interactions between parasites and their hosts play a fundamental role in evolutionary processes. Selection pressures are exerted on parasites and their hosts, usually resulting in high levels of specificity. Such is the case of ectoparasitic bat-flies, but how large-scale spatial gradients affect the dynamics of their interactions with their bat hosts is still unknown. In the present study, we investigated interaction patterns between bats and their ectoparasitic flies (Streblidae and Nycteribiidae), both presenting their peak of diversity in the Neotropical region, along a latitudinal gradient. Using network analyses and parasitic indices, grounded on the latitudinal diversity gradient pattern, we evaluated how spatial gradients affect species interactions and parasitic indices at the biogeopraphic scale, with increasing species richness in interaction networks closer to the tropics, leading to increases in network modularity, size, and specialization, and to a decrease in nesting and connectivity. We conducted a literature review, focusing on studies done in the Neotropical region, and own data. We obtained a bat richness of 97 species parasitized by 128 species of ectoparasitic flies, distributed into 57 interaction networks between latitudes 29° S and 19° N in the Neotropic. Network metrics and parasitic indices varied along the latitudinal gradient, with changes in the richness of bats and their ectoparasitic flies and in the structure of their interactions; network specialization, modularity, and connectance increase with latitude, while network size decreases with latitude. Regions closer to the equator had higher parasite loads. Our results show that interaction network metrics present a latitudinal gradient and that such interactions, when observed at a local scale, hide variations that only become perceptible at larger scales. In this way, ectoparasites such as bat flies are not only influenced by the ecology and biology of their hosts, but also by other environmental factors acting directly on their distribution and survival.

Association of bat flies (Diptera: Streblidae) and bats: Richness and host specificity in Western Mexico

As part of a widespread ecological study on the ectoparasites of bats in Western Mexico, we report new information on the specificity, and distribution of bat flies in a geographical transition zone between the neartic and neotropical zones. Fifteen (15) species of bats representing three families (Mormoopidae, Phyllostomidae, and Vespertilionidae) were collected in 10 locations throughout western Mexico. A total of 276 bat flies, representing 6 genera and 25 species, were identified four species of the bat flies are new records for the region indicating an expansion of the distribution for Trichobius corynorhini (Cockerll, 1910), T. hoffmannae (Guerrero & Morales-Malacara, 1996), T. intermedius (Peterson & Hürka, 1974) and Nycterophilia natali (Wenzel, 1966). These records update the species richness of streblids to 40 species in the state of Jalisco, representing 65.6% of the total number of 61 species of streblids recorded in Mexico. The interaction network showed a high degree of specialization of the bat flies towards their hosts (H2' = 0.92). Similarly, the specificity indices showed that there is a high ecological specificity (SI) with an average of 92%. of all the bat flies was associated with their primary hosts, while the average value of specificity of the phylogenetic trees (S_TD) of the six streblid species that presented more than one host was 1.7%, indicating a high specificity. The results of this study provide relevant information on bat-parasite associations and highlight the need for further research to obtain information on the geographic distribution of streblids and their hosts.

Review of studies about bat-fly interactions inside roosts, with observations on partnership patterns for publications

Pressures from anthropogenic disturbances have triggered a wealth of studies focusing on the assessment and mitigation of the negative impacts of these disturbances on inter and intraspecific ecological interactions, including bats and bat flies in their roosts. The heterogeneity of research methods employed for these studies and the scientific imbalance between countries may constrain advances and the consolidation of the knowledge on this subject. We reviewed the literature regarding bat and bat-ectoparasite interactions in roosts assessing global research trends and patterns of author collaborative work to be able to identify key questions for future studies and potential initiatives to improve the knowledge on this subject. Current information available has mostly come from the Americas and is predominantly focused on the recognition and description of parasite-host interactions between bats and bat flies. Our findings suggest the value of increasing collaboration for future research, as several countries with largely diverse environments and high organismal richness are disconnected from the countries that produce the most publications in this area, and/or have low records of publications. These regions are in the Global South, mostly in South American and African countries. We suggest that more collaborative networks may increase scientific production in the area, and that investing in local research development and enhancing partnerships for publications may strengthen the field. These research programs and collaborations are key for the development of conservation strategies for bats and bat flies, for their roosts, and for understanding bat and bat-ectoparasite interactions.

Effect of seasonality and microclimate on the variation in bat-fly load (Diptera: Streblidae) in a cave bat assemblage in a dry forest

Seasonality causes fluctuations in the availability of resources, affecting the presence and abundance of animal species. These fluctuations can have an impact on parasite-host relationships, which in turn can be exacerbated by microclimatic changes to which bat-flies are exposed. We characterized the bat-fly load and evaluated the effect of seasonality on five bat species in a dry forest. We evaluated variations in microclimatic conditions inside the cave Cerro Huatulco between seasons and the response of the bat-fly load. We collected 1165 bat-fly specimens belonging to 16 species from 688 bats. The obtained results indicate that the mean abundance and infestation intensity exhibited changes between seasons in Artibeus jamaicensis, Desmodus rotundus, Glossophaga soricina, and Pteronotus parnellii. In the case of the effect of microclimate conditions, we observed that prevalence is negatively correlated with temperature in G. soricina, while mean abundance and mean infestation intensity were negatively related to temperature in A. jamaicensis and G. soricina. The present study provides significant information about host-parasite relationships in a dry forest and discusses the relevance of abiotic and biotic factors that could affect host-parasite interactions, as well as the importance of each parasite load parameter for the understanding of this interaction.

Bat flies (Diptera: Streblidae) of phyllostomid bats (Chiroptera: Phyllostomidae) from the mountainous central region of Veracruz, Mexico

The studies of bat flies of the family Streblidae Kolenati, 1863 in Mexico have intensified in the last five years, usually providing new geographical records of species and new bats host records. Currently, the Mexican fauna of streblids is composed of 59 species, representing 26% of total global species richness. Veracruz is one of the states with a high number of species in Mexico with 69% of species recorded in the country. We sampled a total of 527 bats of four subfamilies and 12 species, collecting a total of 870 specimens of 19 species of streblids. Megistopoda proxima (Séguy, 1926) and Paratrichobius longicrus (Miranda Ribeiro, 1907) were the most abundant species in the collection and are the two species found in a higher number of bat species. We provide comments on the taxonomy and host species for bat flies, increase the species records for this state, and add new host records for some streblids, contributing to the knowledge of streblid fauna of the mountain central region of the state of Veracruz, Mexico.

Ornithodoros dyeri (Parasitiformes: Ixodida: Argasidae) parasitizing Leptonycteris yerbabuenae (Chiroptera: Phyllostomidae) in Mexico

Parasites are a selective force that shape communities and ecosystems. Hosts represent a food source, habitat, and a way to disperse. In recent years, investigations dealing with bats and their role as hosts to numerous parasitic organisms, including metazoan ectoparasites and endoparasites have increased, and soft ticks (Parasitiformes: Ixodida: Argasidae) are among the best known. In Mexico, 16 species of soft ticks associated with bats have been reported up to now, but there are no specific records of soft ticks parasitizing Leptonycteris yerbabuenae in the country. Herein, we record for the first time the presence of Ornithodoros dyeri parasitizing L. yerbabuenae and report an extension of its geographic distribution. The same tick species was also recorded from the California leaf-nosed bat (Macrotus californicus). Data on prevalence, mean intensity, mean abundance, tick identification, and possible scenarios of life cycle associations for O. dyeri and one of its hosts, L. yerbabuenae, are discussed.

Arthropods Associated with Mammals. Their Importance as Part of the Richness in a Biosphere Reserve in Mexico

The Chamela Biological Station (ChBS) is located in the Pacific Coast of Mexico in the State of Jalisco. This represents one of the core areas of the Chamela-Cuixmala Biosphere Reserve, characterized by one of the most threatened ecosystems, the tropical dry forest. Although accumulated knowledge of biological diversity, only few studies have been focused on ectoparasites or ectodytes associated with mammals, only 23 arthropod taxa had been recorded. In order to increase knowledge about arthropods associated with Mexican mammals, the objective of this work was to record the richness of arthropods (mites, ticks, lice, and fleas) associated with small and medium-sized mammals in the ChBS. A total of 81 hosts belonging to four orders, six families and nine species were captured. From these hosts, 4,946 arthropods were recovered: 4,007 mites, 673 ticks, 230 lice, and 36 fleas. Among medium-sized mammals, Nasua narica (L.) and Didelphis virginiana Kerr showed the highest levels of richness, with six arthropod taxa; among rodents, Heteromys pictus (Thomas) had the highest number of associated species (five). Within the 22 arthropod taxa registered in the present work, 12 represent new records for the reserve, and 3 represent new records for Mexico. With this study, the arthropod fauna associated with mammals in the ChBS has been raised to 38 taxa. In terms of biological conservation, knowledge of the species that inhabit natural reserves must be a priority, since this represents the baseline for species protected, not only in Mexico but around the world.

Structure and composition of Nycteribiidae and Streblidae flies on bats along an environmental gradient in northeastern Brazil

Bats can be parasitized by several arthropod groups, including ectoparasitic flies. The high host specificity is a common phenomenon between flies and bats. In recent years, more efforts have been employed to understand how environmental variables can influence richness and parasitic load (PL). However, many gaps still need to be filled to better understand this issue. We analyzed the PL of flies on bats sampled in three environments with different rain volume and vegetation types to verify if PL is correlated with rainfall and if there are differences in the PL on bats within and between environments. Overall, there was no correlation between rainfall and PL in the same environment, nor a difference between the three environments. When tested separately, Seba’s short-tailed bats (Carollia perspicillata (Linnaeus, 1758)) had a difference in prevalence of flies between environments and flat-faced fruit-eating bats (Artibeus planirostris (Spix, 1823)) had a greater abundance of flies in the rainy season in a semiarid area. There was no difference in PL between male and female bats. Our results suggest that bat–fly interactions are driven by several factors, not only by the amount of rainfall or vegetation, and that different host species may respond differently with no obvious general pattern.