EVALUATION OF TEA TREE EXTRACT FORMULATION FOR THE CONTROL OF THE COTTON APHID, APHIS GOSSYPII (HOMOPTERA: APHIDIDAE) ON CAPSICUM ANNUUM IN THE GLASSHOUSE

Abstract

Under laboratory and glasshouse conditions, the insecticidal activities of the essential oil obtained from leaves of the tea tree plant by steam distillation was evaluated against the cotton aphid, Aphis gossypii. The results showed that tea tree essential oil affected the aphid population causing a higher mortality of A. gossypii. This study showed that the 50 μL/mL concentration of tea essential oil caused 85.67% mortality after 24 hrs exposure time when used as contact treatment. However, the mortalities at 10, 20 and 30 μL/mL were 18.33, 21.67 and 70%, respectively, after 24 hrs of exposure. Conversely, the residual treatment was the most effective on the cotton aphid, with 100% mortality at the concentration of 50 μL/mL after 24 hrs of exposure to the essential oil. In contrast, the mortalities of A. gossypii were 15.00, 24.44 and 92.78% at the concentrations of 10, 20 and 30 μL/mL, respectively, after 24 hrs of exposure. The formulation of the tea tree essential oil was enormously potent in reducing the cotton aphid population on the sweet pepper, but was slightly phytotoxic to the potted plants. No significant differences were observed between tea tree oil formulations compared with the chemical pesticides, Karate and botanical insecticide, Levo. Based on our findings, the tea tree essential oil can be used as a botanical pesticide against A. gossypii after modifying it to reduce the phytotoxicity on the plants.