Influence of Neem Oil on the Large Pine Weevil, Hylobius abietis L. (Coleoptera, Curculionidae)

The large pine weevil, Hylobius abietis (L.) (Coleoptera, Curculionidae), is the most important pest affecting boreal and temperate conifer forest regenerations in Europe and Asia. Weevils feed on the bark of newly planted coniferous trees causing seedling mortality, stein deformation, and reduced growth. The loss of seedlings without synthetic pesticide treatment may be very high during the first 2-3 years after planting. Having regarded to environmental protection the natural insecticides like neem formulations could replace the chemical control. The effects of natural cold-pressed neem (Azadirachta indica A.Juss) oil (biopreparation NEEM EC (10 000 ppm azadirachtin) produced by the Indian Neem Tree Company) on the maturation feeding of H. abietis was tested in laboratory and field experiments. NEEM EC was tested at concentrations of 2% and 10%. Feeding on food sources treated with neem oil was significantly depressed in laboratory choice tests. A strong antifeedant effect (antifeedant index (AFI) = 0.35-0.62) was revealed for both sexes depending on the concentration of neem oil. In field test, during the whole season weevils damaged the treated 4-year-old Norway spruce seedlings significantly less (< 50%) than untreated control plants (100%).