MONITORING BARK BEETLE POPULATIONS - EFFECTS OF TEMPERATURE

Annual catches of the spruce bark beetle Ips typographus in pheromone-baited traps were largely unaffected by the current season temperature. Extremely warm or cold summers may have had a slight impact on the catches. Monitoring data from traps should therefore provide valuable information about population levels. Analyses of temperature parameters from the previous year indicate a significant correlation between May-June temperatures and trap catches. Models incorporating mean maximum May-June temperatures from the previous year showed good correlations with actual catches, but the correlation was improved when May-August temperatures from the year of trapping are included. The data are from 64-80 traps deployed on 20 sites in Akershus in south-east Norway during the period 1981 to 1990.