SEX-SPECIFIC EMERGENCE OF IPS TYPOGRAPHUS L. (COLEOPTERA: SCOLYTIDAE) AND FLIGHT BEHAVIOR IN RESPONSE TO PHEROMONE SOURCES FOLLOWING HIBERNATION

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Abstract
Emergence patterns, sex ratios, and dispersal characteristics of Ips typographus L. (Coleoptera: Scolytidae) emerging from hibernation sites were studied under field conditions. A total of 8666 emerging beetles were caught in 14 tent-traps, covering brood tree stumps at 3 different hibernation sites. Samples of these beetles were sexed at frequent intervals. The proportion of females increased as emergence progressed and the overall proportion of females was 62%. A total of 3433 beetles emerging after hibernation were marked and released on 19 separate occasions. The recapture rates were 13 and 4% in nearby and distant pheromone traps, respectively. Recaptures were recorded at distances of up to 1800 m. Beetles were able to respond and fly to pheromone sources shortly after emergence without prior feeding or prolonged flight activity. Trapping and marking techniques, temporal and spatial emergence patterns, seasonal sex ratio changes, and factors influencing pheromone trap catches are discussed.