Bacillus thuringiensis, deltamethrin and spinosad side-effects on three Trichogramma species.

One biological insecticide, Bacillus thuringiensis (Berliner) (Bacillales Bacillacae), and two chemical insecticides, deltamethrin and spinosad, were assessed for their effects on immature stages and adults survival of Trichogramma cacoeciae Marchal, Trichogramma bourarachae Pintureau et Babault and Trichogramma evanescens Westwood (Hymenoptera Trichogrammatidae) from Tunisia. The egg parasitoids were collected on Ectomyelois ceratoniae (Zeller) (Lepidoptera Pyralidae) in pomegranate orchard (Punica granatum L.). Deltamethrin and spinosad proved to be harmful to the parasitoid development stages and B. thuringiensis 100 g hl -1 formulation was characterised as slightly harmful only to T. bourarachae prepupae stage. However, B. thuringiensis 70 g hl -1 formulation proved to be harmless towards all the development stages of the tested Trichogramma species. As regards insecticides persistence on pomegranate leaves, B. thuringiensis actions on all studied Trichogramma species were comparable with those of the control, regardless of the day after insecticide treatment. However, spinosad and deltamethrin residues were lethal for all Trichogramma adult species, even six days after treatment.