Insecticidal effects of Moldavian dragonhead, Dracocephalum moldavica, essential oil on the parasitoid wasp Habrobracon hebetor and its hosts Anagasta kuehniella and Plodia interpunctella

Habrobracon hebetor Say is a larval ecto-parasitoid of several moths. In this study, toxicity of Moldavian dragonhead (Dracocephalum moldavica L.)essential oil on Mediterranean flour moth (Anagasta kuehniella Zeller), Indian meal moth (Plodia interpunctella Hubner) and H. hebetor parasitoid waspwere assessed. Essential oil of D. moldavica was extracted by hydrodistillation method using a Clevenger apparatus and its chemical constituents were detected by Gas Chromatography-Mass Spectrometry (GC-MS). Piperitenone Oxide (19.03%), Piperitone Oxide (13.74%) and Citral (9.79%) were identified as the main constituents of the essential oil. It was found that 50% lethal concentration (LC50) values of the essential oil against H. hebetor, A. kuehniella and P. interpunctella adults estimated were 0.995, 9.631 and 10.252 μl/l air, respectively. In order to assess the sub-lethal effects, adult wasps were exposed to LC25 of D. moldavica essential oil and then the demographic parameters of live parasitoids were evaluated. The intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0), gross reproductive rate (GRR) and mean generation time (T) were significantly decreased by essential oil. Results of the present study indicated that the essential oil of D. moldavica can be effective in the management of A. kuehniella and P. interpunctella. However, simultaneous application of D. moldavica essential oil and the parasitoid wasp H. hebetor in the management of aforementioned pests, based on toxicity and negative demographic effects of essential oil on this parasitoid wasp is not recommended.