ALOE VERA (L.) BURM. F. : A HIGHLY USEFUL INDIAN TRADITIONAL PLANT FOR THE MANAGEMENT OF MAIZE STORAGE PEST, SITOPHILUS ORYZAE L. (COLEOPTERA: CURCULIONIDAE)

Abstract

Aloe vera (L.) Burm. f. is an important Indian traditional plant possessing wide range of biological activities. The present study is aimed to determine the repellent and contact toxicity of methanolic extracts of gel, root and leaf peel parts of fifteen A. vera accessions collected from 15 locations in India against maize storage pest, Sitophilus oryzae(L.). Petri dish choice bioassay and filter paper impregnation methods were used to determine repellent and contact toxicity respectively. Analysis of the results reveals that aloin A, the major metabolite of A. vera, at 0.02% w/v concentration possessed strong repellent activity (85.2 %) than sample AV 11a (gel of A. vera) at 5% w/v (82.7%) after 24-h of exposure. Interestingly, the percent repellency increases up to 5-h in all extracts screened. Aloin A at 0.0024 mg/cm2 showed 58.0% mortality against S. oryzae followed by sample AV 13b (leaf peel) at 0.6 mg/cm2 (56.0%) after 14 days of treatment. The content of Aloin A present in the six A. vera extracts, exhibiting highest toxicity and repellency, was determined by Ultra Performance Liquid Chromatography. The percent repellency and toxicity of A. vera vary with geographical location, plant parts, major metabolite concentration and exposure time. The potentiality of these plant extracts could be useful towards the development of effective bio repellent to S. oryzae in stored maize.