%0 Journal Article
%T Ovicidal Activity of Couroupita guianensis (Aubl.) against Spodoptera litura (Fab.)
%A Kathirvelu Baskar
%A Chelliah Muthu
%A Savarimuthu Ignacimuthu
%J Psyche
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/783803
%X Hexane, chloroform, and ethyl acetate extracts of Couroupita guianensis leaves were studied for ovicidal activity against S. litura. All the extracts showed ovicidal activity against S. litura. Maximum activity was noticed in hexane extract and it showed the least LC50 and LC90 values; the regression equation was also higher than the other extracts. All the analyzed values showed homogeneity variance. The active hexane extract was fractionated and eight fractions were isolated. The fractions were studied at different concentrations. Among the fractions, fraction 8 showed maximum ovicidal activity with least LC50 and LC90 values. Fraction 8 differed statistically from the other fractions; the regression equation value was higher than the other fractions. All the P values obtained from regression analysis were significant. The results of the present investigation clearly suggest that the active fraction could be purified to isolate active compound(s) and could be used to develop an insecticidal formulation to control economically important agricultural pests. 1. Introduction India is an agricultural country and more than 80% of the population depend on agriculture [1]. Pathogenic organisms and insect pests cause crop loss of 120 billion US dollars worldwide and reduce the yield by 20¨C40% [2]. In India, approximately 18% of food grains are lost due to pathogens and insect pests. To control the pests and reduce the loss, different chemical pesticides are used. Application of chemical pesticides is polluting the environment, causing ill effects on nontarget organisms, developing resistance, and causing resurgence of pests [3]. These call for an alternative to chemical pesticides through natural means of pest control, including vigorous search for new sources of botanical insecticides [4]. Plant-based pesticides are highly suitable since they have low toxicity, are easily biodegradable, and have multimode of action [5]; they are suitable for organic agriculture [6]. Botanical extracts are used as insecticides for centuries and their active compounds reduce the opportunity for the development of insect resistance [7]. Plants have evolved a range of adaptations to increase their survival and reproduction by minimising the impact of phytophagous insects. Plants defend themselves from herbivores with the help of secondary metabolites produced by them and these secondary chemicals can act as repellents or toxins to herbivores and affect their behaviour, growth, or survival. Volatile plant signals attract natural enemies of the herbivore insect pests [8].
%U http://www.hindawi.com/journals/psyche/2014/783803/