VARIABILITY IN INSECT HERBIVORY AND HEAVY METALS IN SHOOTS OF AMARANTHUS HYBRIDUS L.

ABSTRACT

Herbivores act as an important link between plants and predators and in terrestrial ecosystems, are the primary consumers of plants whose functional role are vital for trophic transfer of energy and pollutants. This study investigates the nature of insect herbivory and heavy metal uptake by Amaranthus hydridus L. in Otofure dumpsite, Benin City, Nigeria, using plant samples from the dumpsite and the neighboring community as control. Other parameters were percentage foliage and general herbivory, plant growth and the concentrations of the heavy metals (Cd, Cr, Mn, Ni, Pb, and Zn) was analyzed using Atomic Absorption Spectrometer (AAS). Amaranthus hybridus at the dumpsite grew significantly more vigorous than their counterpart. Other growth traits were not different statistically (p > 0.05), the extent of leaf herbivory on A. hybridus in the dumpsite was significantly higher than their counterparts at the control site, while the general herbivory at the dumpsite was lower. The general plant herbivory, the number of leaves herbivory and The general foliage herbivory were significantly higher (p <0.05) while the other parameters measured such as The percentage of leaves damaged by herbivory, most damaged leaves and least damaged leaves all showed no difference statistically (p > 0.05). The observed heavy metals were numerically higher in dumpsite but not statistically different in A. hybridus regardless of the sit. In sum, while A. hybridus grows vigorously at the dumpsite and suffer more foliage herbivory than their counterpart outside the dumpsite, there were no sufficient evidence to suspect a significant loads of heavy metal in the primary consumers. However, the elevated levels of heavy metals in A. hybridus shoots may pose some dangers such as tropic transfer through the primary consumers.