Dinâmica espacial de carrapatos (Acari: Ixodidae) na busca por hospedeiros no Parque Nacional do Iguaçu e em fragmentos florestais adjacentes com nota sobre parasitismo humano

Abstract

This thesis was developed to describe the spatial dynamics of ticks (Acari: Ixodidae) in the questing for hosts in the Iguaçu National Park and in adjacent forest fragments, as well as human parasitism. The study took place in the PNI (chapters 1, 2 and 3) and in Atlantic Forest remnants located in the vicinity of the PNI (chapter 4). Ticks were collected through flannel drag, visual search and inspection in humans who participated in scientific activities at the PNI. Our objectives were addressed in four chapters: (i) to verify if tick distribution over time is determined by the type of environment, by the vertebrate activity and to compare the structure and composition of vertebrate and tick communities between the Open Trails (TA) and Control Transects (TCs); (ii) check for any pattern of spatial distribution (at a local scale), questing height, leaf side of ticks; furthermore, to verify if the efficiency of the collection technique was influenced by height and developmental stage; (iii) describe the species, stages, seasonality, as well as anatomical site of the tick bite and analyze if there is a relationship between ticks that bite humans and those host questing in the environment; (iv) describe and compare the tick species in Atlantic Forest remnants (forest fragments) with those from PNI in Foz do Iguaçu and analyze correlations between metrics of the landscape with the abundance, density and richness of ticks. We observed that the number of vertebrate records (n = 5,058) was similar in TAs and TCs (49.6% and 50.4%, respectively) and the type of environment did not interfere with the activity of these animals. However, at the order level, carnivores and lagomorphs were more recorded in TAs and rodents in TCs. The number of ticks and stages did not differ between the types of environments, however, nymphs of Amblyomma coelebs were more abundant in TAs and nymphs and adults of Amblyomma brasiliense in TCs. Estimated species richness (Jackknife 1), dominance and equity were similar between TAs and TCs for all communities evaluated. The Shannon diversity of mammals was higher in the open trails and the beta diversity for all groups evaluated was similar between the two types of environments, showing high similarity in composition. Tick abundance did not increase with host activity. Regarding the spatial distribution of ticks on a local scale (chapter 2), a clustered spatial distribution pattern of nymphs was observed in winter and spring and adults followed this trend only in spring, while in summer the distribution was random. In general, nymphs and adults did not show a specific pattern of positioning in relation to the leaf side, but at the species level, Amblyomma incisum adults were recorded in greater numbers on the abaxial side. Generally, ticks (all together, nymphs and adults) on the abaxial side of the leaves were more detected through transillumination than those that on the adaxial side. The side of the leaf the tick was on was influenced by the ambush height, but not by the developmental stage. Regarding ticks on humans, A. coelebs was the species that bit humans the most despite not being the most abundant one in the environment; most ticks were found biting humans and the minority walking on skin and/or clothing. In this thesis, we also observed that the density, abundance, and richness of ticks was low in the Atlantic Forest remnants when compared to the PNI and that there was a negative relationship of these three variables with the distance from the PNI. In addition, nymphs of A. ovale were found only in fragments adjacent to residential areas. Our results showed that some taxa of vertebrates and ticks use the Atlantic Forest environment of the PNI differently, are grouped in space, that humans are more exposed to A. coelebs bites, there is a low density of ticks in forest fragments, especially in those furthest from the PNI and that A. ovale seems to be favored by some anthropic environments. Future works should investigate in detail the habitat selection in the environment-tick-host relationship. Knowing these aspects in preserved areas helps in understanding the ecological patterns of communities and in preventing vector-borne diseases in the face of environmental changes.