Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 4, 1998
Publication Date: N/A
Interpretive Summary: Highly erodible lands enrolled in the Conservation Reserve Program (CRP) soon will revert to agricultural production. Ground beetles are generalist predators that feed on a variety of agricultural pests. There are many species of predatory ground beetles, which makes them an important element in controlling population sizes of agricultural pests. This study was conducted in the springs of 1995 and 1996, and was designed to determine the effects of conversion of CRP lands to wheat and livestock production on ground beetles. Approaches for converting CRP to agricultural land included no conversion (OWBUM), simulated grazing of CRP grass (OWBM), minimum tillage (WMT)and no tillage (WNT) practices for wheat production. Ground beetles were captured with traps and grouped by conversion type. A few species of ground beetles dominated in total abundance. We captured more ground beetles in 1995 than in 1996. A dry growing season in 1996 may have caused a reduction in ground beetle abundance. We also found differences i ground beetle abundances among conversion types. More ground beetles were captured in OWBM and WNT plots than in OWBUM and WMT plots. The soil and vegetation were less disturbed in OWBM and WNT plots, and this may have contributed to the higher abundances. Our results suggest that none of the conversion strategies studied will have serious adverse effects on ground beetles.
Technical Abstract: Highly erodible lands enrolled in the Conservation Reserve Program (CRP) soon will revert to agricultural production. Ground beetles are generalist predators that feed on a variety of agricultural pests. This study began in the spring of 1995, and was designed to determine the effects of conversion of CRP lands to wheat and livestock production on ground beetle assemblages. Conversion strategies included no conversion of CRP grass (OWBUM), simulated grazing of CRP grass (OWBM), minimum tillage practices for wheat production (WMT), and no-tillage practices for wheat production (WNT). A randomized block experimental design was established with 4 replicates. Ground beetles were captured with pitfall traps and grouped by treatment. More ground beetles were captured in 1995 than in 1996, and abundances within years differed among conversion strategies. Of 73 ground beetle species collected, 9 species accounted for 61.7% of total abundance. .Abundances of these 9 species differed with respect to conversion strategy None of the community parameters (species richness, species diversity, and species evenness) differed among the conversion strategies. Canonical correspondence analysis (CCA) showed that annual and monthly variation were the predominant factors in separating ground beetle assemblages. Lack of rainfall may have accounted for a large portion of differences in abundances between years. A partial CCA showed that OWBM and WNT were the predominant conversion strategies in separating ground beetle assemblages. OWBM and WNT are intermediate disturbance levels between OWBUM and WMT.