Effect of Environmental Conditions on Flight Capacity in Mountain Pine Beetle (Coleoptera: Curculionidae: Scolytinae)

Abstract

Mountain pine beetle (Dendroctonus ponderosae Coleoptera: Curculionidae: Scolytinae) is a major pest of pine (Pinaceae) in western North America. Mountain pine beetle has an obligatory dispersal phase during which beetles fly in search of new hosts to colonize. Climatic factors may influence dispersal in the expanding geographic range of the mountain pine beetle. This study tests mountain pine beetle flight capacity in the laboratory under different abiotic conditions including temperature, light and wind speed. Beetle flight capacity was tested under different temperatures before and during flight and different light regimes in separate computer-linked flight mill bioassays. A wind tunnel experiment tested the effect of wind speed on beetle flight. Pre-flight temperature and temperature during flight did not affect beetle flight capacity (distance or duration). Beetles do, however, use more energy during flight at high temperatures, which could affect host colonization following dispersal by flight of mountain pine beetle in nature. Beetles fly a greater distance and longer duration during a long (18 h) than short (16 h) photophase, suggesting that increased day length with a northern range expansion could affect beetle flight capacity. Although wind speed does not affect flight probability or duration, it affects the number of flights and flight patterns of mountain pine beetles.