Evaluation of the Toxicity of Satureja intermedia C. A. Mey Essential Oil to Storage and Greenhouse Insect Pests and a Predator Ladybird

The use of chemical insecticides has had several side-effects, such as environmental contamination, foodborne residues, and human health threats. The utilization of plant-derived essential oils as efficient bio-rational agents has been acknowledged in pest management strategies. In the present study, the fumigant toxicity of essential oil isolated fromSatureja intermediawas assessed against cosmopolitan stored-product insect pests:Trogoderma granariumEverts (khapra beetle),Rhyzopertha dominica(Fabricius) (lesser grain borer),Tribolium castaneum(Herbst) (red flour beetle), andOryzaephilus surinamensis(L.) (saw-toothed grain beetle). The essential oil had significant fumigant toxicity against tested insects, which positively depended on essential oil concentrations and the exposure times. Comparative contact toxicity ofS. intermediaessential oil was measured againstAphis neriiBoyer de Fonscolombe (oleander aphid) and its predatorCoccinella septempunctataL. (seven-spot ladybird). Adult females ofA. neriiwere more susceptible to the contact toxicity than theC. septempunctataadults. The dominant compounds in the essential oil ofS. intermediawere thymol (48.1%), carvacrol (11.8%),p-cymene (8.1%), and gamma-terpinene (8.1%). The high fumigant toxicity against four major stored-product insect pests, the significant aphidicidal effect onA. nerii, and relative safety to the general predatorC. septempunctatamake terpene-richS. intermediaessential oil a potential candidate for use as a plant-based alternative to the detrimental synthetic insecticides.