ESTIMATES AND MEASUREMENTS OF PINE WEEVIL FEEDING ON CONIFER SEEDLINGS - THEIR RELATIONSHIPS AND APPLICATION

In assessments of pine weevil (Hylobius abietis (L.)) feeding on conif er seedlings in Sweden, positive linear relationships were found betwe en the numbers of attacked seedlings and each of the numbers of seedli ngs killed by pine weevil feeding, the damage score, and the mean esti mated extent of feeding on damaged seedlings. Hence the damage score w as described by polynomial regression on number of attacked seedlings. The influence of environmmental conditions was reflected in variation s of the extent of feeding and seedling mortality. Independent assessm ents of the extent of feeding on an ordinal or percent scale were made by four investigators. The numbers of seedlings with feeding scars ob served in field inspections were consistently lower than the actual nu mbers attacked. The estimates of mean extent of feeding on damaged see dlings varied between investigators within a range of about 10%. The r elationship between the measured area of damaged bark and the estimate d extent of feeding was expressed by linear and exponential regression s.