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AbstractThe aim of this report was to investigate the possible lethal effect of Thymusand Teucriumessential oils against insects. Antimicrobial activity was evaluated by the disc diffusion assay. Relative repellency, fumigation and plant lethality on certain pest species were tested. A higher concentration of thyme (9.95 µL/cm2) essential oil showed the greatest repellent effect against Tribolium confusumand Supella longipalpa. Exposure of pests to 2 µL thyme essential oil (EO) /l air resulted in 100 % mortality in 24 h. Thyme and Teucrium EO induced dose-response mortality of T. confusumlarvae with LC50values ⁣⁣of 45.22 and 38.10 µL/l air, respectively. Maximum lethality was recorded after 24 h and 48 h of exposure to the essence of T. algeriensis. Moreover, a total repellency effect was detected within 1 h of experiment at a concentration of 9.95 µL/cm2. Furthermore, complete lethality (100 %) of the nymph and adult of S. longipalpa(1˂ LT50˂6 h), T. confusum(LT50˂7 h) and the larvae of Blaps nefrauensis(1˂ LT50˂3 h) were observed. Additionally, thymol (0.3% w/w) was shown to induce moderate repellency and fumigant effect against studied insects. Overall, thyme and teucrium essential oils can be alternative botanical pesticides for these insects. But further experiments are needed to justify the insecticidal effect of essential oils used directly on T. confusumin cereal stores. As well, the experimental procedure using low doses of essential oil used for insecticidal potency should be repeated with high doses.

This work was designed to explore the chemical composition, antioxidant, antibacterial and insecticidal activities of Eucalyptus cinereaessential oil collected from Ain Draham, North-Western of Tunisia. GC/MS analysis revealed the identification of twenty two compounds with 1,8-cineole (63.51%), camphene (15.53%), α-pinene (7.55%) and α-terpineol (3.52%) as major components. The antioxidant potential was assessed using two methods 1.1-diphenyl-2-picrylhydrazyl radical (DPPH) and Ferric Reducing Antioxidant Power (FRAP). IC50value was 161.59 µg/mL in the DPPH assay. Moreover, the antibacterial acitivity was evaluated towards Gram positive and Gram negative bacteria (Escherichia coliATCC25922, Staphylococcus aureusATCC29213, Enterococcus faecalisATCC29212). The diameter of inhibition varied between 22 ± 0.57 mm and 7 ± 0.5 mm. The largest one was found in Staphylococcus aureus. However, the smallest one was found in Enterococcus feacalis. The insecticidal potential was established against Ceratitis capitataadults using contact toxicity by topical application. Results revealed that all E. cinereaoil concentrations exhibited strong contact properties. The originality of this research is to offer farmers an innovative solution to control C. capitatabased on the application of natural insecticidal molecules extracted from Eucalyptus cinerea.Moreover, this oil deserves better considerations due to its antioxidant and antibacterial properties.