Estrutura de comunidade e taxonomia de gafanhotos acridoidea (orthoptera: caelifera) em uma floresta primária na flona de Caxiuanã, Pará, Brasil

Abstract

The Orthoptera are the sixth largest group of insects in number of species, among its representatives stand out the true grasshoppers that are included in the superfamily Acridoidea, which presents terrestrial, semi-aquatic and arboreal habitats, its distribution in the environment depends on vegetable composition and climatic factors. This study aimed to know and to understand the community structure, population dynamics and the taxonomy of Acridoidea grasshoppers in a forest area of eastern Amazonia. For ecological study, sampling was performed monthly from 2008 to 2011, in Flona Caxiuanã (01º57'36.82 "S and 51º36,47'61" W), Portel, Pará, 400 km from Belem. The grasshoppers were collected with entomological nets on two tracks, each of 5 km in length and 1 m in width , the sampling site of PPBio Eastern Amazon. Samples were collected from 8 a.m to 16 p.m., due to the diurnal habit of grasshoppers, so a wide variety of individuals and species could be captured. For the taxonomic study, the captured adults in the sampling were examined, in addition to the Invertebrates Collection of specimens of the Goeldi Museum (MPEG). In total, 10,541 specimens were collected, belonging to three families, eight subfamilies, 19 tribes, 40 genera and 51 species. The Acrididae family was the most abundant (71.7%). Among the captured specimens 60.9% were nymphs and 39.1% adults. Among the adults 56.1% were males and 43.9% females. It was detected the existence of two dominant, four abundant, three common and 42 rare or minimal species. Most species are dendrophilia (58.8%) with gregarious habit (62.7%). A dichotomous key was elaborated for the collected adult specimens in the primary forest and the already existing in the MPEG collection, originating from Caxiuanã. 30 new cases were recorded for Flona Caxiuanã, 14 for the state of Pará, six for Brazil and two for the Amazonian region, a new species (Taeniphora. spp.) and the discovery of 47 endemic species for the Amazon. The population peak for adults occurs in the rainy and for the nymphs in the less rainy season. Temperature and humidity are the climatic factors that most influence the population dynamics of grasshoppers. This study contributed to the expansion of the geographical distribution of Acridoidea species and the occurrence of grasshoppers at Flona Caxiuanã as well as to increase the ecological and taxonomic knowledge of Acridofauna in the Amazon region.