Composição da Mirmecofauna (Hymenoptera: Formicidae) em uma área de Cerrado sob pastejo bovino, Caxias, Maranhão

Abstract

The structure of the soil ant community and its modifications depend on environmental factors, vegetation type, fires, temperature variations, humidity, soil management and preparation, among others. Uniformity in environments reduces the variability of ecological niches for the ant community, which decreases its taxonomic richness. In this sense, this study aimed to evaluate the composition of the soil ant fauna in areas under rotational grazing in the village of Ingá. The experimental area comprised 120 ha, divided into two 60 ha paddocks each, and in each area two parallel transects were established, and in each transect ten sampling units were marked, totaling 40 points. The first collection was carried out in April, the rainy season, and the second in October, the dry season in 2022. The collected material was identified to the genus level. For statistical analyses, a database was created using Microsoft Excel software, and for faunistic analyses, the software “R” was used. A total of 5,955 specimens were counted, distributed among eight subfamilies and 21 genera. In April, Area I (resting) had a total of 901 individuals, and Area II (grazed) had 1,275. In October, Area I (grazed) had a total of 1,968 individuals, and Area II (resting) had 1,811 specimens. Area I (resting) showed greater taxon richness in April, while Area I (grazed) showed the greatest abundance of formicids in October. The subfamilies Myrmicinae, Doryline, and Ectatomminae showed the greatest abundance of individuals. Soil temperature did not significantly affect the abundance of individuals; however, precipitation did influence the abundance of individuals. The highest Diversity Index was observed in Area I (resting) in April, while the highest Dominance Index was observed in Area II (grazed) in October. The richness estimator (Chao1) and the accumulation curves measured for the two areas studied, show that the sampling effort was not sufficient to fully measure the genera. The genera Pheidole and Crematogaster showed greater affinity with both areas and traps.