Flight behaviour of Ips typographus L. (Col., Scolytidae) in an environment without pheromones

Abstract

A mark-recapture experiment with Ips typographus (Coleoptera: Scolytidae) was carried out on a 1-ha experimental plot in a healthy spruce stand in Belgium. Recapture of the released beetles was carried out using 96 unbaited standing live trap trees distributed homogeneously over the experimental plot. Less than 0.3 % of the marked beetles were recaptured during three replicates of the experiment. When a pheromone lure was added to one of the trap trees in a fourth replicate, the recapture rate rose to nearly 6 %. Implications for the beetles' dispersal are discussed. Moreover, the take-off rates were found to be strongly correlated to weath- er conditions at emergence: correlations between take-off percentages and the number of sunshine hours per day (r = 0.75), the aver- age daytime relative humidity (r = -0.75) and the cloud cover index at noon (r = -0.63) were found to be highly significant (P < 0.005). &copy; 1999 ditions scientifiques et mdicales Elsevier SAS.