Abstract To understand the ecoepidemiology of fleas and their interactions with domestic and wild animals, it is necessary to decode the cycles of flea abundance in relation to host species and environmental factors. The province of Misiones, known for its biodiversity and land use changes, provides an excellent study location. We assessed the diversity, prevalence, abundance, and parasitic intensity of fleas collected from 1153 rodents and opossums in various environments in the Upper Paraná Atlantic Forest of Argentina, considering phytogeography and land use. Our findings were consistent with previous studies conducted in humid regions of Argentina and the Atlantic Forest in Brazil. Hosts with high population density exhibited greater flea prevalence and abundance, and widely distributed hosts showed higher flea species richness and diversity. Significant similarities in flea similarity indices among phytogeographic areas, especially in forest. Environments with an anthropogenic gradient exhibited marked dissimilarities, with higher species richness and diversity in less disturbed sites. These parameters may be influenced by the presence of polyxenous Ctenocephalides, Polygenis, and Adoratopsylla fleas co-infesting opossum in urban areas. These findings provide valuable insights into the ecoepidemiology of fleas, their relationships with host species, and the impact of environmental factors in a strategic Atlantic forest ecoregion. animals Misiones changes location 115 Brazil areas dissimilarities sites Ctenocephalides Polygenis coinfesting co infesting ecoregion 11 1

Resumen Akodon montensis Thomas es dominante en el Parque Provincial Urugua-í en el noreste de Argentina. Aquí analizamos el efecto de las variables relacionadas con los hospedadores y el medio ambiente sobre la carga parasitaria (PB), que incluye a los Ixodida, Siphonaptera y Mesostigmata (Laelapidae y Macronyssidae). Además, analizamos variables del hospedador y del ambiente sobre la riqueza específica (SL) y abundancia media de ácaros de la familia Laelapidae (MAL), ya que estos fueron el taxón más abundante y el único con cantidad suficiente para el análisis. Las variables PB, SL y MAL se utilizaron con los datos transformados en logaritmos en el análisis. Se usó Anova de una vía para probar las diferencias entre roedores de diferente sexo en un análisis exploratorio, y luego se usó la prueba de Levene para confirmar la homogeneidad de las varianzas. Se probaron las diferencias en estos parámetros entre los estados de madurez sexual de los roedores. Para probar el efecto del sitio de captura y su interacción con el sexo del roedor en MAL y SL, se realizó un Anova de 2 vías. Se utilizó el software PAST. Los resultados sostienen que el sexo del hospedador sería el factor principal que modula PB y MAL, pero no SL. El tamaño y peso de los hospedadores (como proxy de la edad), la etapa reproductiva y el sitio de captura de los roedores, no afectarían ninguna de las variables analizadas. Los resultados obtenidos en el presente estudio contribuyen a la comprensión del papel epidemiológico de los ectoparásitos, principalmente lelápidos.

Abstract Akodon montensis Thomas is the dominant rodent species in the Urugua-í Provincial Park in northeastern Argentina. Herein we analyze the effect of variables related to the hosts and the environment on the parasitic burden (PB), which includes the Ixodida, Siphonaptera and Mesostigmata (Laelapidae and Macronyssidae). In addition, we analyze host and environmental variables on specific richness (SL), and mean abundance of mites of the Laelapidae family (MAL), since these were the most abundant taxon and the only one with sufficient quantity for analysis. The variables PB, SL and MAL were used with the logarithm transformed data in the analysis. One-way ANOVA was used to test differences between rodents of different sex in an exploratory analysis, and the Levene test was then used to confirm the homogeneity of variances. Differences in these parameters were tested between the states of rodent’s sexual maturity. To test the effect of trapped site and its interaction with the sex of the rodent on MAL and SL, a two-way ANOVA was performed. The PAST software was used. The results support that the sex of the host would be the main factor that modulates PB and MAL, but not SL. The size and weight of the hosts (as a proxy for age), the reproductive stage and site of capture of the rodents, would not affect any of the variables analyzed. The results obtained in the present study contribute to the comprehension of the epidemiological role of ectoparasites, mainly laelapids.

Abstract: Usually sigmodontine rodents (Cricetidae) are associated with a variety of ectoparasites. However, the studies in northeastern Argentina are scarce. Herein we analyze the ectoparasite component communities associated with four species of sigmodontines in the south of the Province of Misiones. In total, 835 ectoparasites were collected from the 97 rodents examined: 782 mites (Acari, Mesostigmata; S = 7; P = 78.35 %; MA = 8.06), 50 fleas (Hexapoda, Siphonaptera; S = 2; P = 21.65 %; MA = 0.53), and two ticks (Acari, Ixodida; S = 1; P = 2.06 %; MA = 0.02, P < 0.005). The following five species are mentioned for the first time for the northeastern: Androlaelaps rotundus, Gigantolaelaps wolffsohni, Laelaps manguinhosi, L. paulistanensis, and Polygenis (P.) tripus, increasing the biodiversity known for the area. A tendency toward host aggregation was observed for most of the ectoparasites. Out of 10 ectoparasite species identified in the present study, five were collected from a unique host species, and so, species richness varied between three and four in every component community. Since some of the ectoparasites identified may play a role as vectors of pathogens, the obtained results contribute to a better understanding of the ectoparasite-host relationship, which may have epidemiological implications.

Resumen: Por lo general, los roedores sigmodontinos (Cricetidae) están asociados con una variedad de ectoparásitos. Sin embargo, los estudios en el noreste argentino son escasos. Aquí analizamos las comunidades componentes de ectoparásitos asociados con sigmodontinos en el sur de la Provincia de Misiones. En total, se recolectaron 835 ectoparásitos de los 97 roedores examinados: 782 ácaros (Acari, Mesostigmata; S = 7; P = 78.35 %; MA = 8.06), 50 pulgas (Hexapoda, Siphonaptera; S = 2; P = 21.65 %; MA = 0.53), y dos garrapatas (Acari, Ixodida; S = 1; P = 2.06 %; MA = 0.02, P < 0.005). Las cinco especies siguientes se mencionan por primera vez para el noreste: Androlaelaps rotundus, Gigantolaelaps wolffsohni, Laelaps manguinhosi, L. paulistanensis y Polygenis (P.) tripus, y aumentan el conocimiento sobre la biodiversidad del área. Se observó una tendencia hacia la agregación para la mayoría de los ectoparásitos. De las 10 especies de ectoparásitos identificadas en el presente estudio, cinco se recolectaron de una especie hospedadora única, por lo que la riqueza específica varió entre tres y cuatro en cada comunidad componente. Dado que algunos de los ectoparásitos identificados pueden jugar un rol en la transmisión de patógenos, los resultados obtenidos contribuyen a una mejor comprensión de la relación ectoparásito-hospedador, que puede tener implicaciones epidemiológicas.