Effect of plant oils on the infestation of rhyzopertha Dominica (fab.) in wheat, triticum aestivum linn

Abstract

Six oil treatments, viz., Neem (Azadirachta indica A. Juss), Castor (Ricinus communis), Karanj (Pongamia pinnata), mustard (Brassica juncea), Eucalyptus (Eucalyptus melanophloia) and Taramira (Eruca sativa) were evaluated at three dose levels (0.1, 0.5, and 1.0% v/w) against the lesser grain borer, Rhyzopertha dominica (Fab.) infesting wheat, Triticum aestivum Linn. An untreated check (the control) was maintained for comparison. The maximum protection was provided by Neem oil at 1.0 per cent (no adult emerged up to 270 days) followed by castor oil and Taramira oil at 1.0 per cent (no adult emerged up to 90 days of treatment). The maximum number of adults were recorded in the grain treated with Eucalyptus oil used at 0.1 per cent (9.3-22.0), Karanj oil at 0.1 per cent (6.0-20.7), and castor oil at 0.1 per cent (2.0-23.0). The maximum grain damage was recorded with use of Eucalyptus oil at 0.1 per cent (28.7-64.7), Karanj oil at 0.1 per cent (18.7-60.0%), and Eucalyptus at 0.5 per cent (18.0-58.0%). No grain damage was recorded in 1.0 per cent Neem oil-treated grain, for up to 270 days. For up to 90 days of treatment, no grain damage was recorded in 1.0 per cent castor oil treated grain, and no grain damage was recorded in 1.0 per cent Tarmira oil treated grain for up to 90 days of treatment. No adverse effect of plant oils was observed on seed viability for up to 270 days of treatments.