This study evaluated the insecticidal bioassays of four known plant oils against the 4th larval instar of the khapra beetle, Trogoderma granarium (Everts). Mortality% increased with increased
concentrations of oils and exposure time LC25 & LC50 showed the efficacy of cinnamon oils, followed by black seed, lemon, and then camphor oils. They induced biochemical changes on T.
granarium adults with LC50 compared to control, which were tracked by analysis of carbohydrate-hydrolysis enzymes to measure phosphatase enzymes changes post-treatment. Acid phosphatase enzyme was significantly decreased when treated with black seed, lemon, and camphor oils,
but highly increased with cinnamon oil compared to control. Alkaline phosphatase was decreased significantly post-treated with black seed and lemon oils, but increased significantly after
camphor and cinnamon oils treatment compared to control. Trehalase enzyme was significantly
decreased, but invertase and amylase decreased significantly except in cinnamon oil, which increased significantly compared to control. All oils showed significantly less activity in acetylcholinesterase, glutathione S-transferase, and cytochrome P-450 monooxygenase compared to control. When the 4th larval instar was treated with LC25 of cinnamon oil (0.91%), male perception
of sex pheromone and female pheromone production were impacted. Pheromone production and
response were much higher in untreated beetles than in treated ones.