Indices of population and diversity in arthropods in savanna fallow farm fields of Kano, Nigeria

Abstract

Arthropods are diverse and make vital contributions to ecosystem functions, notably in pollination, organic matter degradation, and as prey to other animals. Also, some arthropods create menace in fields and in food stores; and some are agents of diseases to other organisms. In this work, we sought data on the population features of arthropods in fallow farmlands within Bayero University Kano, New Campus and adjoining marginal fields during April to November 2018. We randomly sampled four replicate plots of 100m x 100m, with each plot traversed by two transects of 100m. The transects were further divided into 10-point stations from which samples of five full-arm (180°) sweeps of 40 cm diameter were taken. Non-flying arthropods were sampled using pitfall traps on 10 random, 10m x 10m sub-plots made out from the larger plots. Population indices, namely, diversity, apparent density, dominance, evenness and richness were determined. The pitfall traps yielded 10 orders of arthropods compared to the sweep net with only five. The mean apparent population densities/ha^-1 were significantly higher for the pitfall trap (1017/ha^-1) than 320/ha^-1 for the sweep net. The density also differed significantly amongst certain orders. Further, all the population indices had higher values for the pitfall trap method than for the sweep net. There were strong positive correlations between arthropod abundance and rainfall pattern. Because of the looming impact of global climate changes and increasing loss of biodiversity, further investigation is recommended to focus on conservation goals.