Chemical components and insecticidal effects of Lavandula angustifolia and Origanum vulgare essential oils on the growth different stages of Habrobracon hebetor Say (Hymenoptera: Braconidae)

Habrobracon hebetor Say is an ectoparasitoid of larval stage of various lepidopteran pests. In this study, fumigant toxicity of Lavandula angustifolia and Origanum vulgare essential oils on the different growth stages of H. hebetor were assessed at 26 ± 2 °C, 60 ± 5% RH, and a photoperiod of 16:8 (L:D) h. Essential oils were extracted from the plant samples using a Clevenger-type apparatus where the plant material is subjected to hydrodistillation. The chemical constituents of essential oils were detected by Gas Chromatography-Mass spectrometry (GC-MS). Glass vials containing 250 ml were used for the experiments. Chemical analysis by GCMS displayed 1,8-Cineol (45.31%) and Camphor (15.78%) for L. angustifolia and Pulegone (37.83%) and 1,8-Cineol (17.02%) for O. vulgare as major constituents. LC50 values of L. angustifolia and O. vulgare essential oils were 0.06 and 0.08 μl for larval stage, 0.29 and 1.39 μl for pupal stage, 0.23 and 0.91 μl for female adults, and 0.17 and 0.23 μl for male adults, respectively. Fumigant bioassays revealed that L. angustifolia oils were more toxic than O. vulgare oils against all stages of H. hebetor. This research indicates that O. vulgare essential oils have less toxicity on H. hebetor and recommends as a compatible botanical compound with this biocontrol agent in integrated pest management programs.