Individual study: Predatory insects are more abundant after minimum tillage than after deep ploughing in a conventionally farmed wheat crop; an experiment at the University of Agriculture, Nitra, Slovakia
Gallo J. & Pekar S. (2001) Effect of ploughing and previous crop on winter wheat pests and their natural enemies under integrated farming system in Slovakia. Anzeiger fur Schadlingskunde, 74, 60-65
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A replicated controlled trial at the University of Agriculture, Nitra, Slovakia (Gallo & Pekar 2001) found that predatory insects were more abundant after minimum tillage than after deep ploughing in a conventionally farmed wheat crop. Most pest insects were less abundant in a given year under minimal tillage than in ploughed plots. This group included thrips (Thysanoptera), bugs (Hemiptera), beetles (Coleoptera), sawflies (Hymenoptera), moths (Lepidoptera) and flies (Diptera). Only sawflies in the family Tenthredinidae and some bugs (Heteropetera) were more abundant on minimal tillage plots. Natural enemies, which included flies (Diptera), wasps (Hymenoptera) and beetles (Coleoptera) were more abundant after minimal tillage than after ploughing, although this was not true for hoverflies (Syrphidae). Pest insects were less abundant after minimum tillage. Two 50 m2 study plots were ploughed to 24 cm deep, and two were ploughed to 15 cm deep (minimal tillage) each year from 1994 to 1996, and planted with winter wheat. Insects were collected with a sweep net in 5 m2 patches of each plot, weekly from April or May to June or July in 1995, 1996 and 1997.