AIR-TEMPERATURE AS A LIMITING FACTOR FOR FLIGHT ACTIVITY OF 2 SPECIES OF PINE BARK BEETLES, IPS-TYPOGRAPHUS L AND PITYOGENES-CHALCOGRAPHUS L (COL, SCOLYTIDAE)

Single catches of bark beetles in pheromone baited traps were registered by the aid of a new instrument. It consists of an electronical weather station in connection with a pheromone trap with infrared sensors as additional equipment. So it was possible also to register weather data at the moment of every catching event. It could be shown that the flight behaviour of both species of bark beetles was influenced by air temperature. 1. typographus did not fly beneath a minimum temperature of 16.5-degrees-C. There was also an upper limit of 30-degrees-C for flight activity of this species. P. chalcographus has a threshold of temperatures about 16.8-17-degrees-C for activity. No upper limit of temperature could be observed up to 35-degrees-C. Both of them, I. typ. and P. chalc., reacted very sensitive and spontaneous to these temperature thresholds.