Abstract

COMPARATIVE STUDIES ON THE LARVICIDAL EFFICACY OF OCIMUM SANCTUM AND ANNONA SQUAMOSA AN AGAINST RED COTTON BUG, DYSDERCUS SINGULATUS

A. Kavitha Amirthanayagi, K. Radhika and V. Ramamurthy*

Abstract

The red cotton bug, Dysdercuscingulatus (Fab). is an important pest of cotton and okra. Although synthetic chemical insecticides can control it, the side effects are enormous. Dysdercuscingulatus (Fab.) is a serious pest of cotton and distributed all the cotton growing region of India. The application of easily degradable plant compounds is considered to be one of the safest methods to control insect pests and vectors as an alternative source for the synthetic pesticides. The study indicated that essential compounds were the only chemical used for the control of mosquito larvae while extract was used as the control of adult mosquitoes. The essential compounds were extracted by steam distillation and their chemical composition determined by Gaschromatography coupled to mass spectroscopy. A study was made to monitor the effect of plant extracts on different instars of larvae and pupae of mosquito vector D.cingulatus. Bio-assay was made using the solvent acetone to find out the median lethal concentration. Plants, like Ocimum sanctum and Annonasquamosa which possess insecticidal properties are seemed to be better vector control agents than the synthetic xenobiotics. These results suggest a potential utilization of the extracts of these two plant species for the control of Dysdercuscingulatus.

Keywords: Dysdercuscingulatus, insecticide, larvicidal activity, mosquito control, phyto-compounds, GC-MS analysis, Ocimum sanctum and Annonasquamosa.