Insecticidal Effects of Some Plant Leaf Extracts in the Control of Insect Field Pests of Amaranthus hybridus L

A field trail was conducted at the Botanical garden of department of Plant Science and Biotechnology, Abia State University, Uturu, Nigeria to assess the insecticidal effect of aqueous leaf extracts of Azadirachta indica, Ocimum gratisimum and Vernonia amygdalina on insect field pests of Amaranthus hybridus. The experimental design was randomized complete block with three replicates. Aqueous leaf extracts of the powdered samples of these plants were uniformly sprayed on the experimental material at 30 g/l twice weekly from 10 to 38 days after sowing. A. hybridus plants sprayed with aqueous leaf extracts of the different plants had lower percentage leaf and leaf area damage compared to the control. Percentage leaf damage followed this order: A. indica < V. amygdalina < O. gratisimum < control, with percentages leaf damage of 25-27%, 34-46%, 32-49% and 47-73%, respectively. Percent leaf area damage were 18.6%, 31%, 45.8% and 61.2% for A. indica, O. gratisimum, V. amygdalina and control, respectively. Significantly (P<0.05) higher plant height, root length and dry matter production were obtained in plants sprayed with aqueous leaf extract of A. indica in contrast to the other treatments, which had comparable values with the control. The results indicate that A. indica if properly harnessed can be used as a biopesticide in the control of insect field pest of A. indica .

Biopesticide; Field pest; Amaranthus hybridus; Leaf extract