Jacquet, M., Harala, E., Lemperiere, G. and Poteri, M. 2012. Preliminary Results of a Slow Release Formulation of Imidacloprid for the Control of the Large Pine Weevil (Hylobius abietis L.). Baltic Forestry 18(1): 83-90.

The large pine weevil Hylobius abietis L. (Coleoptera: Curculionidae) is the most damaging insect for young conifer seedlings in Europe. Laboratory feeding tests were performed to determine the dose effect of the granular formulation of Imidacloprid product ‘Suscon Forest®’ (Nufarm Ltd.) on the bark consumption of insects and the effect on their physiological conditions. Seedling shoot growth of two-year-old container Norway spruce (Picea abies) seedlings was measured at the same time as the seedlings were lifted for feeding tests, which was at 41 days with the nursery field and 61 days with the greenhouse grown seedlings. The shoot growth of the seedlings was not affected by the product. In the feeding tests, untreated seedlings were more damaged compared to treated ones. With the greenhouse seedlings, an average area of 209.7 mm² of bark was consumed on the untreated seedlings versus 29.1 and 17.4 mm² on treated seedlings that had been supplied with 5 and 10 grams of the product respectively. A better control effect against pine weevils was obtained with greenhouse-grown seedlings than with field planted seedlings.

Key words: Curculionidae, Hylobius abietis, Imidacloprid, feeding test, Picea abies, container seedling.