PHENOLOGY AND DISPERSAL OF HARPALUS RUFIPES DEGEER (COLEOPTERA, CARABIDAE) IN AGROECOSYSTEMS IN MAINE

The phenology and movement of adult Harpalus rufipes DeGeer (Coleopter a: Carabidae) was studied in Presque Isle and Stillwater, Maine during 1989-1996. Samples collected from pitfall and light traps indicated H . rufipes is the dominant ground beetle species (up to 78.4% of the to tal Carabidae) in Maine potato agroecosystems. This species overwinter s as both adults and larvae. Overwintered adults became active in earl y May and densities peaked by the end of June. Overwintered larvae sta rted pupating in mid-July; the resulting summer adult population peake d by mid-August. Seasonal adult population catches in light traps coin cided with the two peak pitfall trap catches in most years. Most of th e light trap catches (97%) represented sexually immature adults sugges ting that long-distance dispersal by flight occurs before oviposition. Mean tethered flight durations for females and males were 188.5 +/- 2 42.6 (mean +/- SD) and 100.4 +/- 84.4 min, respectively. The mean disp ersal distances per day by ovipositing females after mark and release was 9.8 +/- 5.2 m in a potato field and 11.2 +/- 7.0 m in an oat field . The mean dispersal distance per day by males was 6.5 +/- 6.1 m in a potato field and 5.7 +/- 4.7 m in an oat field. This suggests that adu lt H. rufipes are very active on the soil surface and have potential t o numerically respond to localized weed seed densities, which is an im portant characteristic of a weed seed predator.