Effects of monoterpenes on digestive enzymatic activities and some constituents involved in intermediary metabolism of <i>Trogoderma granarium</i> (Everts) (Coleoptera: Dermestidae)

Our study aims to evaluate the repellency and fumigant toxicity profiles of 3 essential oil components (EOCs) namely Limonene, Menthol and Linalool against <i>Trogoderma granarium</i> last instar larvae. Limonene is the most toxic chemical tested. Various parameters are examined, including digestive enzymes, enzymes of intermediary metabolism (alanine aminotransferase (ALT), alkaline phosphatase (ALP) and aspartate transaminase (AST)), and oxidative stress biomarker (esterase). The results highlight the insecticidal efficacy and repellent activity of three EOCs, which is correlated with the applied concentrations and the exposure time. Furthermore, the biochemical analyses indicate that the treatment significantly decreases the activity of digestive enzymes such as protease, α-amylase, chitinase and lipase, and triglyceride levels. The specific activity of enzymes related to intermediary metabolism reveals an increase in the level of ALT, ALP and AST in treated <i>T. granarium</i> larvae compared to controls. Finally, EOCs also increase the esterase activity in treated larvae compared to controls.