Acute toxicity of an imidacloprid-based product (Confidor 200 SL) to pupae of
the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae),
and its effects on life history traits and population growth in F1 generation
of the surviving parasitoid females of a commercial strain (?Dutch? strain,
D) and two local populations from Serbia (Bujanovac, B; Negotin, N) were
examined in laboratory bioassays. All trials were carried out at 27?1?C
temperature and 60?10% relative humidity, and under 16/8 h daylight/darkness
photoperiod in four replications. In acute toxicity bioassays, tobacco leaves
carrying parasitoid pupae were treated with a series of symmetrical
concentrations (800, 400, 200, 100, 50 and 25 mg a.i./l) covering a 10-90%
mortality range. The product based on imidacloprid, applied directly onto
parasitoid pupae at mean lethal concentrations (LC50) determined in the acute
toxicity assays (30 mg/l, 20 mg/l and 25 mg/l, for populations B, N and D,
respectively), significantly affected the survival of females developed from
the treated pupae, extended the duration of juvenile development (by 1.81,
1.59 and 1.73 days for populations B, N and D, respectively), significantly
reduced total parasitism of females D (25.92 %), total female adult emergence
in populations B (27.48 %) and D (17.92 %), and significantly reduced the
instantaneous rate of increased only of females N (4.23 %). Considering the
high acute toxicity of the imidacloprid product to the pupal stage of E.
formosa, and significant reductions in life table and population parameters,
imidacloprid is not considered compatible for simultaneous use with the
parasitoid E. formosa. A more precise assessment of risks involved in the use
of that insecticide requires a more detailed testing in the field. The
implications of these results for the concept of integrated control of the
greenhouse whitefly are discussed.
The application of an Integrated Control on Eggplant for the Greenhouse Whitefly, Triαleurodes vαporαriorum