Heavy metals in some termite species and their nests in Ojo, Lagos, Nigeria

Abstract

Termites feed on decaying organic matter including plant parts and wood, concentrating heavy metals in the process. The main campus of Lagos State University was surveyed for termite species and their heavy metal contents. Nests including mounds, wooden structures and discarded wood products were observed for termite activities and the insect samples collected for identification and subsequent metal analyses. Composite samples of selected termite species and the soil or wood dust around them were respectively digested and analyzed for the presence of Iron (Fe), Potassium (K), Sodium (Na). Zinc (Zn) Cadmium (Cd), Copper (Cu), Chromium (Cr), Lead (Pb), Nickel (Ni) and Cobalt (Co) using Atomic Absorption Spectrophotometer (AAS). The results showed that Macrotermes bellicosus (Isoptera: Macrotermitinae), Reticulitermes flavipes (Isoptera: Rhinotermitidae) and Kalotermes flavicollis (Isoptera: Kalotermitidae) occurred on the main campus of Lagos State University in Ojo, Lagos. Heavy metal analyses of termite castes showed that M. bellicosus worker had Ni, Fe, Cd, Co, Pb, Na and K with Fe having the highest concentration of 24.6 mgL^-1 while Co had the least (0.03mgL^-1). The reproductive caste had the highest concentration (4.68 mgL^-1). The Soldier of M. bellicosus showed the presence of all metals detected in its worker caste excluding Cu & Ni with Fe having the highest concentration (5.12mg/L). The Soldier and Worker castes of Kalotermes similarly showed the presence of the same metals as M. bellicosus soldier. Analyses of data by Kyplot showed high correlation between heavy metal concentrations in study termite species relative to their nest materials.

Keywords: Heavy metals, Termites, Worker, Soldier, Winged Reproductive, Kyplot analysis