Radar observation and aerial capture of mountain pine beetle, Dendroctonus ponderosae Hopk. (Coleoptera: Scolytidae) in flight above the forest canopy

Abstract

An outbreak of the mountain pine beetle ( Dendroctonus ponderosae Hopk.) in central British Columbia, Canada, has reached an unprecedented size and intensity and has been spreading. The 2005 emergence and subsequent flight of mountain pine beetle was studied using direct observation of emergence, weather radar imagery, and aerial capture. To verify that the daytime, clear-air radar returns seen during this period were indeed generated by airborne mountain pine beetles, aerial sampling in the area covered by the radar was performed using a drogue capture net towed by a single-engine light aircraft. Results verify that airborne mountain pine beetles are being detected by the weather radar and that, during the emergence period, significant numbers of mountain pine beetles can be found at altitudes up to more than 800 m above the forest canopy. An estimate of transport distance indicates that mountain pine beetles in flight above the forest canopy may move 30–110 km·day–1. An estimate of the instantaneous density of mountain pine beetles in flight above the canopy on flight days in 2005 indicate a mean (maximum) density of 4950 (18 600) beetles·ha–1.