The effects of cattle ranching on the communities of necrophagous flies (Diptera: Calliphoridae, Mesembrinellidae and Sarcophagidae) in Northeastern Brazil

Most of the ongoing decline in biodiversity, worldwide, is due to human activities, in particular, the expansion of agriculture. In this context, we highlight the need for studies of the taxonomic groups that can provide insights into the dynamics of the ecological communities facing anthropogenic impacts. For this, we evaluated the effects of the environmental changes caused by cattle ranching on five phytophysiognomies (Cerrado Savanna, Amazon Forest, Palm Forest, Marshland, and Mangrove) in the state of Maranhão, Brazil. We tested the hypothesis that the species composition, abundance, and richness of the families Calliphoridae, Mesembrinellidae, and Sarcophagidae (Diptera) are affected by ranching in each of the phytophysiognomies. Specimens were collected at 90 sites, including 45 anthropic sites (cattle ranches) and 45 preserved habitats, using traps baited with bovine lung. We collected 15,023 calliphorids (11 species), 10,772 sarcophagids (52 species), and 241 mesembrinellids (one species). The results indicated significant differences between anthropic and preserved habitats in the species composition, abundance, and richness of sarcophagids, in particular in the Amazon Forest, where the highest species richness was recorded in the anthropic environments. In the case of the calliphorids and mesembrinellids, by contrast, significant differences were found in species composition and abundance in only in four of the five phytophysiognomies analyzed (excluding the Cerrado Savanna), while species richness only varied in the palm forest and marshland. In all cases, lower values were recorded in the anthropic environments. These results indicate that the insects of the families Sarcophagidae, Calliphoridae, and Mesembrinellidae respond differentially to the anthropic activity (cattle ranching) and can be used to evaluate this type of anthropogenic impact systematically. In addition, the Amazon Forest was the phytophysiognomy most impacted by this activity in the Brazilian state of Maranhão.