Developmental impairment and Oviposition deterrence in Callosobruchus maculatus (Fabricius) infesting Vigna radiata (L.Wilczeck) upon treatment with five different plant products

Abstract

Background/Objectives: The toxic synthetic pesticides must be replaced by safe, cheap, non-toxic, target-specific insecticides such as natural plant products. This study is to investigate the ovipositional and eclosion inhibitory activities of five plant products against the pulse beetle, Callosobruchus maculatus infesting green gram (Vigna radiata). Method: Fine powders prepared from various parts of the plants Piper longum, Adhatoda vasica, Illicium verum, Cinnamomum zeylanicum and Syzygium aromaticum at various concentrations (0.2, 0.4, 0.6, 0.8 g) were added to 30 g of V. radiata seeds and two pairs of adult C. maculatus were introduced. Inhibitory effect of oviposition was studied by counting the number of eggs periodically (24, 48, 72, 96 and 120 hours) and the eclosion failure was also assessed. The control was similar to the experimental setup except for the absence of plant powders. Findings: The oviposition deterrence values which provide a comparison between the control and treatments showed S. aromaticum to be the strongest deterrent with a value of 85.77 followed by C. zeylanicum (76.33), P. longum (66.91), I. verum (62.96) and A. vasica (42.93) at 0.8 g. Also S. aromaticum recorded the highest eclosion failure of 22.06% and the lowest with A. vasica (11.08%) at 0.8 g. Statistical analysis showed an overall significant difference (p < 0.05) between the different plants, concentration wise. Though all the five selected plants exhibited insecticidal activity, S. aromaticum was the strongest in inhibiting oviposition and impairing larval growth of C. maculatus. Novelty: Previous works have demonstrated the insecticidal activity of the essential oils of S. aromaticum and C. zeylanicum but this study has shown that prepared powders of both these spices are quite effective at low concentrations, so can be easily used by farmers.