Diversidade de Odonata (insecta) do parque Nacional da Amazônia, Pará, Brasil

Abstract

The order Odonata is an important group of insects for aquatic ecosystems and has been frequently used in conservation studies as a bioindicator of priority areas for preservation. In this context, a survey of the diversity of Odonata species was carried out in 18 streams, belonging to the Tapajós river basin, located in the Amazon National Park (PARNA), Pará, Brazil. Using an entomological net in a 150 m transect over a period of one hour, we sampled adults of Odonata in the 18 streams during the dry season. To estimate species richness, we used the first order non-parametric Jackknife estimator controlled by sampling effort. To test sampling efficiency, we used a species accumulation curve, using the Jackkinife estimator with 1,000 randomization. Subsequently, we evaluated the local biodiversity with two ecological indices: Shannon (H') and Simpson (D)). A total of 301 individuals were collected, with a total of 40 species. The suborder Zygoptera presented the highest abundance, being 90.4%, in relation to the 9.6% of the suborder Anisoptera in the sampled igarapés. The estimated species richness was 55.11 ± 4.4 (mean ± standard deviation), and the collection efficiency was 75.58%. We recorded a considerable diversity of species (H' = 2.95; D = 0.08). As for the frequency of occurrence, of the 40 species, 31 were classified as accidental (77.5%), six as accessory (15%) and three as constant (7.5%). The high integrity characteristics of the Amazon National Park (PARNA) probably allow a great availability of resources for several species, as observed for the order Odonata. In detail, we recorded the presence of species with a high level of ecophysiological requirement, such as Heteragrion bariai, which had the highest abundance, frequency of occurrence and dominance, and some species of the genera Chalcopteryx and Mecistogaster, all indicators of preserved environments. Our results demonstrate that PARNA has an excellent state of conservation, considering that it is home to a high diversity of dragonfly species. It is extremely important to carry out new surveys of odonatofauna to better understand species that had low records and also for the monitoring and conservation of the park.