Field evaluation of plant extracts for the control of diamond moth (Plutella xylostella Linnaeus) infesting cabbage (Brassica oleracea Linn)

Cabbage (Brassica oleracea Linn.) is one of the important vegetables grown worldwide. Insect pests have been a major constraint to its production with some reported to have developed resistance to commonly available synthetic insecticides. In order to find alternative control for these pests, field experiments were conducted in the early seasons of 2011 and 2012, to evaluate the efficacy of three plant extracts, Tephrosia vogelli Hooks, Zingiber officinales Rosh and Lantana camara Spanish flag, applied at 5, 10 and 25 % w/v concentrations Delthamethrin (a synthethic insecticide) and an unsprayed plot were included as positive and negative controls respectively. Plots were arranged in a Randomized Complete Block Design (RCBD), with three replications. Mean Data over the two planting seasons were subjected to the analysis of variance and significant means were compared using the least significant difference (L.S.D) at P < 0.05. Z. officinales extract effectively control P. xylostella larvae at all concentrations with 25 % w/v gave the best yield of 0.50 kg/ha while T. vogelii and L. camara extracts were as effective as Deltamethrin at different concentrations and hours on diamondback-moth (P. xylostella) adult The present findings indicated that effective botanicals against Diamondback moth adult and larvae of cabbage can be formulated from extract of T. vogelii, L. camara and Z. officinales at 25 % concentration respectively