Fumigation toxicity and oviposition deterrency of four plant essential oils on cowpea beetle

In order to find alternatives for conventional pesticides, the fumigant toxicity and ovipositional deterrency of essential oils of summer savory, pennyroyal mint, ostokhodus and rosemary were tested against adults of cowpea beetle Callosobruchus maculates F. (Col.: Bruchidae). The experiment was conducted using a completely randomized design with six concentrations and five replications. Experiment was carried out at 30 ± 2 ˚C and 60 ± 5% R. H. under dark condition. Concentration of 560 μl/l air essential oils of summer savory, pennyroyal mint, ostokhodus and rosemary caused 95.78, 87.78, 57.33 and 65.11% mortality of adults, respectively. LC50 values of essential oils of summer savory, pennyroyal mint, ostokhodus and rosemary were found to be 69, 106, 322 and 205 μl/l on adults, respectively. Essential oils of all tested plants, showed significant reduction of ovipositional rate of cowpea beetle. The highest concentration (190 μl/lair) of essential oils of summer savory, pennyroyal mint, ostokhodus and rosemary caused 83.22, 92.45, 62.34 and 73.24% ovipositional deterrency, respectively. Essential oils of summer savory and pennyroyal mint showed the highest control on cowpea beetele. Therefore they could be recommended as safe pesticides for control of storage pests.