Exploring the Insecticidal and Repellent Activity of Garlic Essential Oil against Sitophilus oryzae (L.) Infestation in Stored Maize

Abstract

The potential of garlic essential oil for its insecticidal and repellent properties against the rice weevil, Sitophilus oryzae was investigated through various bioassays. The results of the contact toxicity assay showed that the mortality rates were dependent on the concentration of the garlic essential oil, and its effectiveness increased with time. This was evident from the decreasing median lethal doses (LC50) over the course of the study, ranging from 7.13 µl/ 20g of seeds (1 DAT) to 3.40 µl / 20g of seeds (5 DAT). The highest repellency rate of 88.89 per cent was achieved with a concentration of 6µl over a 4-hour period. This finding was further supported by the negative preference indices, which ranged from -1.0 to -0.1. With regard to fumigant toxicity assay, the LC50 values decreased as the study progressed, ranging from 4.72 µl /96cm3 (1 DAT) to 1.70 µl/96cm3 (5 DAT). Thus, garlic essential oil can be considered as a potent botanica compound on account of its contact, repellent and fumigant toxicity properties against Sitophilus oryzae. The results of this study underscore the potential of garlic essential oil as a promising compound for the management of S. oryzae.