Exploring essential oils of Slovak medicinal plants for insecticidal activity: the case of Thymus alternans and Teucrium montanum subsp. jailae

Thymus alternans andT eucrium montanum subsp. jailaeare medicinal and aromatic plants, typical of Slovakianflora, producing bioactive essential oils. In the present study, we evaluated the insecticidal potential of theessential oils, obtained by hydrodistillation from the plant aerial parts and analysed by GC-MS, as insecticidalagents. For the purpose, they were assayed against three insect species acting as agricultural pests or vectors ofmedical relevance, such as the common housefly,Musca domesticaL., the lymphaticfilariasis vector,Culexquinquefasciatusand the Egyptian cotton leafwormSpodoptera littoralis;α-cypermethrin was tested as positivecontrol. The two essential oils exhibited a different chemical profile, with monoterpenes and sesquiterpenesbeing the main fractions in the essential oils fromTh. alternansandT. montanumsubsp. jailae, respectively.Insecticidal tests showed that theT. montanumessential oil was effective againstS. littoralis(LD50(90)= 56.7(170.0)μg larva−1) andCx. quinquefasciatuslarvae (LC50(90)= 180.5 (268.7) mg L−1), whereasT. alternansessential oil displayed good toxicity againstM. domesticaadults (LD50(90)= 103.7 (223.9)μg adult−1). Overall,our results add useful knowledge about the potential of Slovakianflora as a source of botanicals for the eco-friendly management of insect pests and vectors.