The use of essential oils has emerged as an ecofriendly solution for controlling different pests, particularly insects of stored products. Essential oils (EOs) from Thymus capitatus (TC) and Origanum compactum (OC) have received less attention for these bioactivities. Therefore, our study aimed to assess the repellent, antifeedant and contact toxicity of their EOs against a major stored product pest Tribolium castaneum. Besides, GC-MS was also carried out to determine the compounds responsible for the observed bioactivities. Regarding contact toxicity, LC₅₀ values were 0.58 and 0.35 μL/cm² for TC and OC after 24 h of exposure, respectively. For the repellent effect, the percentage of repellency (PR) was variable across different concentrations and exposure durations. TC exhibited the best PR (98%) after 3 h of exposure at 0.031 μL/cm². For prolonged repulsive effect (24 h), TC sustained its repulsive efficacy with a PR of 90% at 0.062 μL/cm² followed by OC with a PR of 88% at 0.125 μL/cm². As for the antifeedant effect, both EOs had a significant impact on nutritional indexes, especially the feeding deterrent index and relative consumption rate. OC displayed a notable effect, causing 59% of feeding deterrence at 1.92 μL/pellet. These multifaced effects can be explained by the high content of carvacrol in both EOs (OC: 90% and TC: 78%). These multifaced effects demonstrated through different exposure routes and bioassays promote the use of T. capitatus and O. compactum EOs as a sustainable management strategy to control T. castaneum.

This study aimed to assess the antioxidant capacity, the insecticidal, feeding deterrence, repellent effects against Tribolium confusum of the essential oil (EO) and the organic extracts (ME) of Origanum vulgare. The chemical composition of the EO revealed the presence thirty-nine components dominated by carvacrol (81%). With respect to the EO, the ME acted as a potent free radical scavenger with IC50 values of 0.127 and 0.058 mg/mL, respectively. The EO exhibited the most significant toxicity compared to the ME with a mortality of 62 and 20% at 0.08 µL/insect after 24h whereas the EO expressed the highest repellency compared to the ME with a PR of 70 and 38% after 24h. As for feeding deterrence, both samples influenced all nutritional indexes. The findings found in this work might help in the promotion of oregano as natural antioxidant, antifeedant, repellent and insecticide as an alternative to conventional harmful ones.

Essential oils (EOs) are concentrated volatiles renowned for their strong fumigant, contact, feeding deterrence, and repellent effects. These oils can disrupt vital functions and the activity of essential enzymes in major stored product pests like Tribolium castaneum. Hence, the study of the physiological effects of these EOs can provide a better understanding of the impact of EOs and propose new strategies for the control of this pest. Therefore, this review aims to review available data regarding the potential impact of EOs on T. castaneum enzyme activities, biomarkers, gene expression, and transcriptomic profile. Articles retrieved provide interesting findings regarding the activity of digestive enzymes (α-amylase, alanine aminotransferase, and aspartate aminotransferase) detoxification enzymes (cytochrome P450 monooxygenase, esterase, glutathione S-transferase), antioxidant enzymes (catalase, superoxide dismutase) and acetylcholinesterase, ATPase, in adults and larvae exposed to different EOs. Moreover, some articles evaluated the content reserve products (proteins, lipids, carbohydrates) and biomarkers linked to stress (reactive oxygen species), lipid peroxidation (conjugated diene, malondialdehyde), and antioxidant system (reduced and oxidized glutathione). Other molecular aspects were also evaluated, including transcriptomics and gene expression, to assess the physiological interactions after exposure to EOs.

The study aims to evaluate the behavioral and insecticidal effects of Ruta angustifolia EO (RAEO) against larvae and adults of a major pest insect, Tribolium castaneum. RAEO exhibited a strong repellency against both adults and larvae where percentages as high as 74 and 72 % of PR (Percentage of Repellency) were recorded respectively, at 0.47 μL/cm² after 2 h. Regarding the antifeedant bioassay, no feeding deterrence was recorded in adults while an increase in appetite was registered in larvae exhibiting −80 % of FDI recorded at 0.2 μL/pellet. In terms of feeding preference, the response significantly depended on the developmental stage (F=97.19, P<0.05) and larvae were attracted to treated pellets recording percentages of 84 and 73 % of PI (Preference index) after 5 and 30 min at 0.05 μL/pellet; on the other hand, adults expressed a repulsive behavior at 0.2 μL/pellet with a PI of −81.1 (20 min), and −69.2 % (30 min). Regarding topical application toxicity, a significant difference was observed between larvae and adults (p<0.05 F=174.56). The study promotes the use of RAEO as a repellent and bioinsecticide for the control of larvae and adults of T. castaneum.