RECAPTURE OF DISPERSING BARK BEETLE IPS-TYPOGRAPHUS L (COL, SCOLYTIDAE) IN PHEROMONE-BAITED TRAPS - REGRESSION-MODELS

Parent (re-emerged) spruce bark beetles (Ips typographus L., Col.; Sco lytidae) beginning a second host-seeking flight were collected in pher omone-baited traps. These beetles were marked with fluorescent powder of different colors and released from a point source (9-16 June 1989) within a spruce, Picea abies L., forest (Jurbarkas forest district, Li thuania). Some of the marked beetles were recaptured with pheromone-ba ited traps in two experiments: (1) traps at 10 m and (2) traps 30, 60, 90, and 120 m distances from the release point. Of 5920 and 5030 beet les that took flight in the two experiments, average recapture rates w ere 5.64+/-1.17% (+/-SEM) on traps at 10 m distance, and 1.62+/-0.21, 0.88+/-0.23, 0.27+/-0.08, and 0.03+/-0.03% on traps at the respective distances from 30 to 120 m. Parameters of several regression models we re fitted with the Simplex algorithm (SYSTAT statistical software) to recapture data. The best fitting models were those of power, and an ex ponential form. A discussion of the biological meaning of certain coef ficients in the equations is presented with regard to bark beetle disp ersal.