Sublethal effects of a Beauveria bassiana-based mycopesticide on Dutch and Serbian populations of Encarsia formosa (Hymenoptera: Aphelinidae)

ABSTRACTThe effects of a Beauveria bassiana-based product (trade name Naturalis-L; strain ATCC 74040) on the behaviour, life history traits and population growth of one commercial Dutch strain and two local Serbian populations (Bujanovac and Negotin) of Encarsia formosa Gahan (Hymen.: Aphelinidae) were evaluated in laboratory bioassays. In a two-choice test, parasitoids from all tested populations preferred to parasitise untreated whitefly nymphs over those treated with 1, 0.5, 0.25, 0.125 and 0.0625 ml/l of the mycopesticide. The longevity of adults of population Bujanovac exposed for 48 h to residues of the mycoinsecticide applied at the LC50 concentration was 1.4 days shorter than that of control wasps. Total parasitism was significantly reduced (by 17.5, 26.2 and 31.4% for the Negotin, Dutch and Bujanovac populations, respectively) compared to control, as well as adult emergence in the F1 generation (reductions of 20.3 and 26.7%, for the Dutch and Bujanovac populations, respectively). The instantaneou...