Field and laboratory studies on the effects of neem ( Azadirachta indica) oil on the feeding activity of the large pine weevil ( Hylobius abietis L.) and implications for pest control in commercial conifer plantations

• Published in: Crop protection 2003-06, Vol.22 (5), p.753-760
• Main Authors: Thacker, J.R.M., Bryan, W.J., McGinley, C., Heritage, S., Strang, R.H.C.
• Format: Article
• Language: English
• Subjects: Azadirachta indica; branches; Conifer; conifers; field experimentation; Forestry; Hylobius abietis; laboratory experimentation; neem extracts; Neem oil; Pest control; pests; plantations; seedlings; trees
• ISSN: 0261-2194; 1873-6904
• DOI: 10.1016/S0261-2194(03)00041-3

Field and laboratory studies were carried out to assay the effects of neem oil on the feeding activity of the large pine weevil Hylobius abietis L., the most important pest in restocked commercial conifer plantations thoughout northern Europe. The neem oil formulation was supplied as the product Bugban ®, a formulation that is derived from commercial plantation mahogany in India. This formulation is not, at present, registered for use in commercial forestry within the UK. Field experiments were carried out on Forestry Commission land near Aberfoyle, Scotland. These experiments assayed the effects of neem oil dose rate, concentration and treatment area on weevil feeding activity over a 3-month period during 2001. Laboratory experiments assayed the effects of neem oil concentration on weevil feeding activity on twigs in choice and no-choice situations. Both field and laboratory studies indicated that the neem oil had a significant deterrent effect on weevil feeding. In the field experiments all the control trees died. In contrast, trees that were treated with undiluted neem oil remained unaffected by the resident weevil population. The data indicate that neem extracts may have a role to play in protecting seedling trees from attack by pine weevil during their first year of growth in the field. Since neem extracts are regarded as environmentally friendly chemicals for pest management, the use of these formulations would fit with the current government's strategy of reducing the use of synthetic chemicals.