Ixodes chilensis Kohls, 1956 (Acari: Ixodida: Ixodidae): re-description of the female, description of the nymph, and phylogenetic position inferred from mitochondrial DNA sequences of the 16S rRNA gene

Morphological and molecular data on the bat flies, Basilia silvae (Brèthes, 1913) and Trichobius parasiticus Gervais, 1844 parasitizing Chilean bats

Among mammals, bats harbour the greatest taxonomic diversity of ectoparasitic arthropods. This is mainly due to their high mobility, wide distribution range and gregarious social behaviour. In Chile, 17 species of bats have been reported; however, their ectoparasitic arthropofauna has been little studied. There are currently 12 taxa recorded, belonging to two classes and associated with only four species of bats. This study aimed to investigate the diversity of parasitic flies associated with bats in three ecoregions: Atacama Desert, Chilean Matorral and Valdivian temperate forest. During 2021, using mist nets, bats were captured in Anzota caves (Atacama Desert ecoregion), Huelquén and Alto Jahuel (Chilean Matorral ecoregion), Cherquenco and San Patricio (Valdivian temperate forest). Each bat was carefully checked during a 15-min interval for the collection of ectoparasites. The arthropods were deposited in vials with 96% ethanol. A total of 26 bats corresponding to three species (Vespertilionidae: Histiotus magellanicus Philippi, 1866, Myotis arescens (Osgood, 1943); Phyllostomidae: Desmodus rotundus (Geoffroy, 1810)) were captured from which a total of 142 ectoparasitic arthropods were collected. Bat flies were separated/identified under a stereomicroscope. Additionally, from the fieldwork, we report the presence of other ectoparasites associated with Chilean bats. In our study, we report new host-parasite associations between Trichobius parasiticus Gervais, 1844 (Diptera: Streblidae) on D. rotundus, and Basilia silvae (Brèthes, 1913) (Diptera: Nycteribiidae) in M. arescens in Chile. Our study extended the latitudinal range of distribution for B. silvae to Araucanía region, and we report for first time T. parasiticus in the country. Additionally, partial sequences of the cytochrome c oxidase I gene were obtained from these specimens. Although there is slight morphological variation in the specimens of T. parasiticus, phylogenetic analyses suggest that they correspond to the same species. The sequences generated for B. silvae represent the first for the species. Authors recommend the use of an integrative approach in the identification of ectoparasites in poorly studied ecoregions and hosts. The integration of different markers is necessary to determine more precisely the phylogenetic relationships between South American populations and species of the genera Basilia and Trichobius.

Worldwide host associations of the tick genus Ixodes suggest relationships based on environmental sharing rather than on co-phylogenetic events

BACKGROUND

This study aims to capture how ticks of the genus Ixodes gained their hosts using network constructs. We propose two alternative hypotheses, namely, an ecological background (ticks and hosts sharing environmentally available conditions) and a phylogenetic one, in which both partners co-evolved, adapting to existing environmental conditions after the association took place.

METHODS

We used network constructs linking all the known pairs of associations between each species and stage of ticks with families and orders of hosts. Faith's phylogenetic diversity was used to evaluate the phylogenetic distance of the hosts of each species and changes occurring in the ontogenetic switch between consecutive stages of each species (or the extent of the changes in phylogenetic diversity of hosts for consecutive stages of the same species).

RESULTS

We report highly clustered associations among Ixodes ticks and hosts, supporting the influence of the ecological adaptation and coexistence, demonstrating a lack of strict tick-host coevolution in most cases, except for a few species. Keystone hosts do not exist in the relationships between Ixodes and vertebrates because of the high redundancy of the networks, further supporting an ecological relationship between both types of partners. The ontogenetic switch of hosts is high for species with enough data, which is another potential clue supporting the ecological hypothesis. Other results suggest that the networks displaying tick-host associations are different according to the biogeographical realms. Data for the Afrotropical region reveal a lack of extensive surveys, while results for the Australasian region are suggestive of a mass extinction of vertebrates. The Palearctic network is well developed, with many links demonstrating a highly modular set of relationships.

CONCLUSIONS

With the obvious exceptions of Ixodes species restricted to one or a few hosts, the results point to an ecological adaptation. Even results on species linked to groups of ticks (such as Ixodes uriae and the pelagic birds or the bat-tick species) are suggestive of a previous action of environmental forces.

Ixodes scapularis (Ixodida: Ixodidae) Parasitizing an Unlikely Host: Big Brown Bats, Eptesicus fuscus (Chiroptera: Vespertilionidae), in New York State, USA

Ixodes scapularis Say is a three-host tick that has been recorded feeding on over 150 different species of terrestrial vertebrates (mammals, birds, and reptiles). This tick is found throughout the northeastern, coastal southeastern, and upper midwestern United States and is considered the most significant vector of tick-borne pathogens to humans in North America. Despite its ubiquity and broad host range, I. scapularis previously has not been reported feeding on bats (Chiroptera). However, during 2019 and 2020, larvae and nymphs of I. scapularis were recovered from big brown bats, Eptesicus fuscus (Palisot de Beauvois), at four locations in rural New York State, USA. All Ixodes infested bats were injured and found on the ground; therefore, parasitism by I. scapularis was likely opportunistic. Nonetheless, the large number of pathogens known to be associated with bats and the frequency with which I. scapularis bites people suggest that this host-tick relationship is of at least potential epidemiological significance.