Ecological response of carabid beetles (Coleoptera: Carabidae) to contrasting agroecosystem management
摘要
The use of indicator species to evaluate agroecosystems has been proposed as an effective and practical method for assessing agricultural sustainability. Carabid beetles are sensitive ecological indicators because of their responsiveness to environmental disturbances and land use practices. However, their responses to management practices are not well understood, particularly in Africa. This study aimed to evaluate the abundance, richness, and composition of carabid beetles in various agroecosystems and identify potential indicator species linked to management practices. Carabids were sampled from 2020 to 2021 across four farm systems: conservation grazing, conventional tillage, conservation tillage, and semi-natural grassland. Sampling involved pitfall traps arranged in two transects, each with four traps (totaling eight traps per site), placed 5 m apart, along with active searches conducted in 5 × 5 m quadrats located 10 m from the traps, and spaced 2 m apart from each other. A total of 2,016 individuals representing 14 Recognizable Taxonomic Units (RTUs) were recorded. Conservation grazing practices, particularly natural grassland and rotational grazing, supported significantly higher carabid RTU abundance and richness (P < 0.05), while conventional tillage practices showed consistently negative effects. Community composition exhibited significant variation across different farm types (R2 = 0.45, P = 0.001), with pairwise comparisons revealing substantial differences between most pairs of farm types. Indicator species analysis identified Calosoma sp.1 and Scarites (sp. 1 and sp.2) (stat ≥ 0.99, P = 0.001) as significant indicators of conservation grazing, underscoring their potential as proxies for ecosystem health in the agroecosystem management of South African. These findings suggest the use of carabid beetles as ecological indicators for evaluating the impacts of agricultural management in South African agroecosystems.