Project fit is best under Timber growth and value program topic 4.3 Mitigating losses. Outbreaks of the western hemlock looper (WHL) are characterized by rapid increase, patchy distribution, and significant and extensive tree mortality over large areas in mature cedar-hemlock-spruce forests of BC. Outbreaks occur approximately every 10 years, and last about 4 years. There is currently an outbreak in BC. During the last outbreak (1990-1994) WHL was estimated to have killed 5.5 million cubic metres of timber in the former Nelson Region alone. This represented a serious disruption to normal economic and operational planning, and resulted in unsalvaged timber volume loss. It is known that looper egg counts and the percentage of parasitized eggs provide an estimate of population trends and expected defoliation locations and intensities during outbreaks. With this information management activities such as targeted harvesting or organic insecticide sprays can be planned to mitigate losses. Current egg sampling technology is tedious, time-consuming, and expensive, and requires a specialised extraction process. Project objectives are to 1: Test the effectiveness of a new artificial substrate egg sampling technology for predicting localised western hemlock looper population trends and defoliation severity during outbreaks; and, 2: Compare the efficacy and cost-effectiveness of the new sampling technology against current sampling technologies for WHL. If the new oviposition sampling system proves efficacious, then BC will have a standardised, cheaper, easier, and more robust method that can be installed and collected by non-specialists, and rapidly and easily assessed. The technique will fit smoothly into, and add to the accuracy of, the current monitoring system for WHL. In order to minimise costs, and provide the public with assurance, it is imperative that BC is seen to be using the best available technologies. For defoliator monitoring, advances in fields such as pheromone biology and use, and oviposition sampling mean that new technologies are available that can provide reduced survey costs with as good or better results. These results can in turn be used to improve the cost-benefit and targeting of direct control operations such as harvesting or spraying. This project will address a new technology that has the potential to provide these benefits, as well as complimenting past and current research. It is anticipated that this research will lead to similar possibilities for other defoliators.
Stock, Arthur J., Duthie-Holt, Marnie; Otvos, Imre S.; Maclauchlan, Lorraine E.. 2007. Oviposition traps to survey for population trends and defoliation prediction of the western hemlock looper (Lambdina fiscellaria lugubrosa) (Lepidoptera: Geometridae) in British Columbia. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2007MR387