Individual study: Ground beetle abundance and community composition in conventional and organic tomato systems of California's Central Valley
Clark M.S. (1999) Ground beetle abundance and community composition in conventional and organic tomato systems of California's Central Valley. Applied Soil Ecology, 11, 199-206
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Convert to organic farming
A replicated, controlled study in February-November 1997 in Davis, California, USA (Clark 1999) found that average ground beetle (Carabidae) abundance was 0-17 captures/week in organic plots compared with 0-7 captures in conventional plots of tomato Solanum lycopersicum. Abundance was higher in organic (6 captures/week) than conventional (2 captures) plots in June, but statistically similar at other times. The total number of ground beetles caught since February was higher in organic (averaging 33-46 captures) than conventional (18-22 captures) plots from June to November. Ground beetle species richness was higher in organic (averaging 2.3-3.5 species) than conventional (0.3-1.3 species) plots in June, September and November but not in other months. The organic system received no synthetic chemical insecticides, herbicides or fertilizers and included a legume cover crop prior to and after the tomato crop. Tomatoes were harvested in July. Each treatment was replicated four times in 0.12 ha plots. Beetles were sampled using two pitfall traps placed in the centre of each plot.