Térmitas e seus ninhos: distribuição, abundância e os efeitos da pluviosidade ao longo de 500 KM no sentido Leste-Oeste da Paraíba

Abstract

Termites are eusocial insects from the order Blattaria, infraorder Isoptera. Over 20% of termite species in South American tropical forests build conspicuous nests. Their nests are striking elements of the ecosystem composition and influence the biodiversity of a wide variety of organisms besides termites. Thus, the evaluation of the abundance and distribution of the nests can represent an additional tool in the analysis of the quality of the habitat in tropical forests. The density and volume of conspicuous nests in the East-West direction of Paraíba were estimated in order to evaluate variations of these factors among the studied areas. The study was developed in eight areas of the Atlantic Forest Domains (including “Brejo de Altitude”) and Caatinga. The density of nests was estimated from six areas of 65 X 20 m, randomly established. In these areas, all nests with volume ≥ 2.0 liters were analyzed. A total of 12 conspicuous nesting species were recorded. The subfamily Nasutitermitinae and the food group II (Termitidae with a range of feeding habits including dead wood, grass, leaf litter, and micro -epiphytes) were more representative. Among the study areas, the estimated average nest volume ranged from 17.79 to 254.7 liters and the density ranged from 14.1 to 75.62 active conspicuous nests / ha. There was significant variation between the areas in relation to density (F7,40 = 2.41 and p = 0.03) and volume (F7,40 = 2.45; p = 0.03) of total nests and for Microcerotermes indistinctus , both for density (F6,35 = 6.53, p = 0.00) and for volume (F6,35 = 4.55, p = 0.00). While for Nasutitermes corniger there was no significant variation (F5,30 = 1.28, p = 0.29 for density and F5.30 = 2.04, p = 0.10 for volume). There was no significant relationship between the density, volume and rainfall of total nests and species with wide distribution, as well as there was no significant difference between the height of the species with a wide distribution in the Domains. The nests exist in the highest density in an area of Caatinga, as well as greater volume. There was a significant correlation between rainfall and richness of species (R² = 0.42, p = 0.04, N = 8 and R² = 0.58, p = 0.01, N = 8, respectively) The Jaccard similarity index grouped the areas according to their Domain, while the Morisita group grouped the Caatinga SSTC area with the Atlantic Forest areas. This high density value in the Caatinga was represented mainly by Constrictotermes cyphergaster, a species with strong performance in the cycling of nutrients in areas of the Domain. The high volume in the Caatinga area occurred due to the nests of Syntermes cearensis. It has already been reported in the literature the high size that nests of this genus can present. Within the context of the Caatingas, the SSTC area is considered as a forest refuge. The results indicate an influence of rainfall on the composition and richness of constructing species along the studied gradient.