Insecticidal efficacy and physiological effects of Eucalyptus globulus essential oil and its constituent, 1,8-Cineole against Tribolium confusum (Jacquelin du Val, 1868) (Coleoptera, Tenebrionidae)

The present study aims to evaluate the insecticidal activities of an essential oil extracted from Eucalyptus globulus and a bioactive molecule, 1,8-Cineole against a stored product pest, Tribolium confusum (Jacquelin du Val, 1868). Toxicological tests carried out by fumigation revealed the insecticidal activity of these two treatments with a concentration–response relationship. In addition, the repellency test demonstrated the repulsive potential of these two treatments toward T. confusum. Furthermore, they activate enzymes of intermediary metabolism via an increase in alanine aminotransferase, aspartate transaminase and alkaline phosphatase in T. confusum adults. Moreover, EO and its major component induce an increase of the lipid and carbohydrate contents in adults. Results of nutritional indices showed a decrease in the relative growth rate, relative consumption rate and efficiency of conversion of ingested food, accompanied by a decrease in digestive enzymes, α-amylase, chitinase, protease and lipase in treated series when compared with control. The results obtained indicate the potential use of this essential oil or its main component as an ecologically safe natural insecticide or repellent against stored wheat pests.