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Background: Five species of the Phortica genus (Diptera: Drosophilidae) are known in Europe and the Middle East. Among these, Phortica variegata and Phortica okadai are better known for their role as vectors of the zoonotic eyeworm Thelazia callipaeda. Other species, such as Phortica semivirgo and Phortica oldenbergi, have been studied less. Given the paucity of data about these Phortica spp. vectors, we explored the population dynamics and ecology of Phortica spp. in an area highly endemic for T. callipeada (Manziana, Rome, Central Italy)., Methods: Phortica spp. flies were collected over a 3-year period (2018-2020) during their active season (April-October) with a sweep net while hovering around fermenting fruits or a human operator acting as baits. Collected flies were morphologically identified and tested for a T. callipeada infection and for the presence of Wolbachia, by polymerase chain reaction (PCR). Population dynamics of species collected was associated to environmental drivers through generalized additive models., Results: Of the 5564 flies collected, 90.8% were P. variegata, 9.1% were P. oldenbergi, 0.05% were P. semivirgo, and one specimen was P. okadai. Only P. variegata scored molecularly infected with T. callipeada throughout the 3-year sampling period (1.8%). Phortica oldenbergi, observed consistently during the entire sampling period, exhibited a marked preference for fruit traps, contrasting with the lachryphagous activity of P. variegata. Analysis of environmental drivers of P. oldenbergi and P. variegata population dynamics indicated temperature, wind speed, and pressure as significant factors. In addition, Wolbachia pipientis endosymbiont was detected in P. oldenbergi and P. okadai., Conclusions: For the first time, this study analysed several ecological aspects of Phortica species coexisting in a T. callipeada endemic area, highlighting different behaviors in the same environment and their vectorial role. Notably, this is also the first report of the presence of P. oldenbergi in Italy and P. okadai in Europe, underscoring the importance of extensive sampling for detecting potential vectors and alien species with direct implications for vector-borne disease epidemiology., (© 2024. The Author(s).)

Thelazia callipaeda (Spirurida, Thelaziidae) eyeworm, a zoonotic parasite transmitted by lachryphagus drosophilids, causes subclinical to clinical ocular disease in a wide range of vertebrates, including humans. In the past 20 years, the infection spread primarily in areas where the vector thrives, and now is endemic in many European countries. Recently, this nematode has been reported also in the United States. Here, we describe the first record of the brown bear (Ursus arctos) as a host of T. callipaeda. Eight (26.7%) out of 30 bears were found to be infected with T. callipaeda adult worms. In addition, the parasite was detected in 13 wolves (Canis lupus) sharing the same environment with the brown bears. At the molecular characterization, all nematodes belonged to the haplotype 1, which is the only one recorded in Europe, as yet. This finding demonstrates that brown bears may act as hosts for this parasite, suggesting its potential role in the maintenance of the cycle not only in the wild but also in captivity. Under the above circumstances, the brown bear may represent a potential zoonotic risk for humans, both in rural and urban areas where other reservoirs may be infected., (© 2021 Wiley-VCH GmbH.)