Ground beetle abundance and community composition in conventional and organic tomato systems of California's Central Valley

Ground beetle abundance and community characteristics were compared in toma to systems under conventional and organic management. Beetles were sampled with pitfall traps over a 10-month period during 1997, in plots that had be en under consistent management at the University of California at Davis sin ce 1988. Abundance and species richness were greater in the organic system compared to the conventional system. Six of the 17 species collected were f ound only in organically-managed plots. However, no differences in species diversity or evenness according to the Shannon and Simpson indices were fou nd. These results were found to be consistent with those of most other stud ies on ground beetle communities in conventional and organic annual croppin g systems. (C) 1999 Elsevier Science B.V.