Vertical distribution profile of Colorado potato beetle [Coleoptera: Chrysomelidae] in flight above host, resistant host and non-host fields

Abstract

We evaluated the vertical stratification of Colorado potato beetle (Leptinotarsa decemlineata) (CPB) populations in flight above fields of conventional potato, an insect resistant potato field expressing genes for Bacillus thuringiensis tenebrionis (Btt) toxins and a non-host clover field. Flight interception traps at 0 - 1.2, 1.2 - 2.4 and 2.4 - 3.6 m above ground were used to determine the vertical profiles of the aerial population over each crop for a growing season. The distribution of overwintered and summer CPB catches above conventional potatoes was similar with a significant effect of trap height on catch. The same vertical distribution profile was observed for overwintered CPB and a similar trend for summer CPB above the insect resistant field. Few overwintered beetles were captured over the clover field but enough summer CPBs were caught to detect a trend similar to that on resistant potatoes. Additional data show that more than 70% of CPBs fly less than 4 m in distance at a height of less than 2 m. These data suggest that the vertical flight profiles observed result from local dispersal of resident populations, or low level flights of summer beetles, but not from high level flights of dispersing overwintered adults.