LOCAL DISPERSAL OF OVERWINTERED COLORADO POTATO BEETLE (CHRYSOMELIDAE, COLEOPTERA) DETERMINED BY MARK AND RECAPTURE

Three mark-recapture experiments were conducted to determine patterns of movement in the Colorado potato beetle, Leptinotarsa decemlineata ( Say), over an agricultural landscape in Maryland. In the 1st experimen t, beetles were released from a central point and recaptured 5-20 d af terward in potato trap fields extending outward in 4 compass direction s to a maximum distance of 0.65 km. Approximately 30% of released beet les were recaptured. Recaptures declined rapidly with distance, and a few beetles were recaptured 0.65 km from the release point after 5 d. A stream and a dense winter cover crop may have acted as impediments t o movement over part of the experimental area. In the 2nd and 3rd expe riments, beetles were released at various distances in 4 compass direc tions from a central ''trap'' field and recaptured 5 d later. Recaptur e rates were approximate to 20% when beetles were released at 50 and 1 00 m and 6.5% when released at 300 m. Direction of release was a signi ficant variable in the recapture rate in one of these experiments but not in the other. The results suggest that effective field rotation to reduce beetle population densities from year to year will require a d istance of greater than or equal to 0.5 km.