SPATIAL-DISTRIBUTION OF FLYING NEODIPRION-SERTIFER (HYMENOPTERA, DIPRIONIDAE) MALES IN A MATURE PINUS-SYLVESTRIS STAND AS DETERMINED BY PHEROMONE TRAP CATCH

Field studies were conducted during three years to determine the verti cal (height level) and horizontal (distance from stand edge) distribut ion of flying Neodiprion sertifer (Geoffroy) males in a non-outbreak p opulation. Sticky traps baited with synthetic female pheromone (2S, 3S , 7S-diprionyl acetate) were used in a mature stand of Scots pine (Pin us sylvestris L.) in Central Europe (southern Bohemia). The vertical d istribution was distinct; more males were caught in traps at 9.0-12.5 m height (crown stratum) than in traps at 2.5 or 0.5 m above ground. T he horizontal distribution was rather uniform inside the stand, with o nly small differences between catches near the stand edge ( < 30 m) an d inside the forest. These data show that the main flight of N. sertif er males in high pine stands takes place at the crown level. Implicati ons for the use of pheromone traps in monitoring programs are discusse d.