Captivity of pheromone bark beetle traps differently baited set up in a forest area of Lower Saxony, near Hanover, in 1992 and 1993

In the years 1992 and 1993 black THEYSOHN slit-traps were set up in a fores t area near Hanover, Germany. The traps were baited with combinations of th e synthetic bark beetle pheromones Pheroprax(R), Chalcoprax(R), Linoprax(R) , and Cembrax(R). Their captivity was tested in comparison to singly baited and control traps without pheromone. Additionally, combinations of Pheropr ax + Cembrax and Linoprax + Cembrax were tested. The captivity numbers obta ined from Ips typographus, Pityogenes chalcographus, Xyloterus lineatus and X. domesticus were discussed in relation to the differently baited traps. In the latter three species, females and males were separated. The periods of flight activity of the four Scolytidae baited were ascertained for both years. Concerning the singly baited traps, Pheroprax captured the highest amount o f Ips typographus per trap, its population increased 9% in 1993 related to that of 1992. For P. chalcographus, the combination of the four pheromones resulted in a little higher number of individuals than in singly baited tra ps. Xyloterus lineatus preferred the four-pheromone combination, in which L inoprax was present showing a synergistic effect of baiting. In contrary, t he baiting of X. domesticus was lower by the combined pheromones than by Li noprax alone. The latter was found in lower numbers than X. lineatus. The t rapped amounts of both Xyloterus species were continuously reduced througho ut the years 1989 to 1993. The Coleoptera species, not specially trapped, amounted yearly to 0.6-0.7% of the collected individuals. P. chalcographus was collected to 85-87%, and Ips typographus to 11-14% of the total amount of Coleoptera trapped.