Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen Street East, Sault Ste. Marie, Ontario, P6A 5M7, Canada.
The gypsy moth was accidentally introduced into North America in 1869. Since that time it has expanded its range and is now a serious defoliator of trees in the eastern United States and Canada. The northern edge of its range is now passing through the Great Lakes region and extends as far south as central Florida. Gypsy moth feeds on over 400 tree species in Europe and North America. Early instars generally prefer species of oak and will not readily feed on species of pine or maple unless forced to do so. Our study was initiated to investigate how the attractiveness of extracts of different concentrations from various host and non-host species affect larval behaviour. Resistence to herbivory within and between species may be due to the presence and concentration of growth reducing and mortality inducing factors present in preferred and non-preferred species. We are particularly interested in the role of phenolics as resistance factors. These compounds and their level of concentration may have potential for the protection of tree species important to forestry in integrated pest management programs. The chemical constituents of needles and leaves in host and non-host plants which may affect the feeding behaviour of the European gypsy moth (Lymantria dispar) were investigated by HPLC and then bioassayed for their attractiveness at different concentrations. HPLC results suggest that there are a variety of phenolics which can reduce the growth and survivorship of gypsy moth larvae. However, preliminary results from larval bioassays measuring the attractiveness of the extracts suggest that not only host but, the concentration of active constituents in the extract is an important factor that must be considered.