Nasal Mites of Kelp Gulls (Larus dominicanus) in Brazil: Geographic Distribution and Parasitological Indices

Abstract Purpose This study aims to investigate the occurrence, geographic distribution, and parasitological indices of nasal mites in Kelp Gulls ( Larus dominicanus ) from southern Brazil, as well as to assess whether infection indices differ according to host gender, age class and latitudinally. Methods Nasal cavities from 171 gulls collected in southern and southeastern Brazil were inspected for the presence of mites. Recovered specimens were clarified, mounted on microscope slides, and identified using light microscopy, with selected specimens examined by scanning electron microscopy (SEM). Parasitological indices were analyzed and compared between male and female hosts, as well as among adults, juveniles, and immature gulls. Results Larinyssus orbicularis was detected in 32.7% of the gulls examined, with parasitized hosts recorded in both Rio Grande do Sul and Santa Catarina states, and absent in northern areas. The prevalence of mites was similar among male and female hosts. However, juvenile gulls exhibited a significantly lower prevalence than immatures and adults. A record-high infection intensity of 197 mites was recorded from a single individual, substantially exceeding previous reports for this parasite genus. Heavy infections (> 50 mites) occurred in 21.5% of parasitized gulls. Conclusions This study highlights the expanded geographic distribution of L. orbicularis and provides baseline parasitological data for Kelp Gull. The high infection intensities observed, including heavily parasitized individuals, indicate that nasal mite infections may constitute an important but largely overlooked component of host health.