Individual study: Flying insects in a wheat crop are more abundant after minimum tillage than ploughing; an experiment at the University of Agriculture, Nitra, Slovakia
Gallo J. & Pekar S. (1999) Winter wheat pests and their natural enemies under organic farming system in Slovakia: Effect of ploughing and previous crop. Anzeiger Fur Schadlingskunde-Journal of Pest Science, 72, 31-36
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A replicated controlled trial at the University of Agriculture, Nitra, Slovakia (Gallo & Pekar 1999) found that flying insects in an organic wheat crop - both pests and predators - were more abundant after minimum tillage than after ploughing. Pest insects, excluding aphids (Aphidoidea), were generally more abundant under minimal tillage in a given year. This group included 11 different types of thrip (Thysanoptera), bug (Hemiptera), beetle (Coleoptera), sawfly (Hymenoptera), moth (Lepidoptera) and fly (Diptera). Natural enemies, which included flies, wasps (Hymenoptera) and beetles were also generally more abundant after minimal tillage than after ploughing, although the effect was less strong and not true for hoverflies (Syrphidae). Natural enemy insects were more affected by the previous crop, being more abundant in wheat following a maize crop. 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.