Heavy Metal Accumulation and Arthropod Abundance in Leafy Vegetable Cultivation

Abstract

Heavy metal contamination of soils used for crop cultivation constitutes danger to biodiversity conservation and environmental health. This study therefore investigated heavy metal accumulation in soils used for vegetable cultivation and their effects on the diversity and abundance of arthropods. Analysis of soil samples collected from selected plots used for leafy vegetable cultivation viz; Corchorus olitorius L. (Tiliaceae), Amaranthus hybridus (Amaranthaceae) and Celosia argentea (Amaranthaceae) showed different levels of heavy metal contamination. Insect abundance and diversity from each vegetable plant was also recorded. Zinc was the most accumulated with concentrations ranging from 3.06 mg/kg to 4.99 mg/kg. Copper was next with concentration ranging from 0.71 mg/kg to 0.95 mg/kg in the soil. Cadmium was the least accumulated of all the heavy metals in soils from the three vegetable sites. A total of 22 different insect species were recorded at different physiological growths of leafy vegetables at the study area in 2011/2012 cropping seasons. Hymenia recurvalis was the most abundant insect pest species ranging from 34.86 in A. hybridus to 16.96 in C. Olitorius in 2011. The insect pests’ incidence had a similar trend for both years. The concentration of heavy metals from this study did not exceed safe limits, hence there was a fair abundance and diversity of insects found on the leafy vegetables.

Key words: heavy metals, accumulation, arthropod abundance, insect diversity, Leafy vegetables.