TOXICITY AND REPELLENCE OF PLANT OILS AGAINST TRIBOLIUM CASTANEUM (HERBST), RHYZOPERTHA DOMINICA (F.) AND TROGODERMA GRANARIUM (E.)

Toxicity and repellency of Conocarpus erectus, Rosa indica and Cassia fistula oils extractedby Soxhlet apparatus in two solvents (petroleum ether and ethanol) were evaluated against Tribolium castaneum, Rhyzopertha dominica and Trogoderma granarium . The oils were applied on wheat grains at three concentrations (10, 20 and 30%). The treated grains were offered to targeted insects. The toxicity results revealed that the ethanolic extracts were more effective against T. castaneum than petroleum-ether extracts. Ethanolic extracts of C. erectus proved more effective against T. castaneum followed by ethanolic extracts of C. fistula and R. indica. Petroleum ether extracts proved more effective against R. dominica and T. granarium because petroleum-ether extracts of C. erectus proved more effective followed by R. indica and C. fistula than their ethanolic extracts. The repellency data revealed that petroleum extracts proved more effective than ethanolic extracts against T. castaneum and R. dominica. Conocarpus erectus extracts were more repellent followed by C. fistula and R. indica However, C. erectus proved more effective repellent against T. granarium followed by R. indica and C. fistula. All the leaf-extracts investigated in present study can be better alternatives to synthetic grain protectants and should be further studied for characterization of the active molecules present in these extracts.