The effects of organic farming on pest and non-pest butterfly abundance

Butterfly transects were conducted on eight pairs of organic and conventional farms in the UK in 1994, and ten pairs of farms in 1995. Each transect included areas of conventional and organic farmland. All species seen, and the abundance of each species, were recorded separately for the uncropped field boundary and the crop edge. In both years, significantly more non-pest butterflies were recorded on organic than on conventional farmland, and more non-pest butterflies were recorded over the uncropped boundary habitat than over the crop edge habitat in both systems. By contrast, there was no significant difference in either year in the abundance of two pest species, Pieris brassicae (the large white) and Pieris rapae (the small white) between the two systems. Implications of the results far the conservation of butterflies within agricultural systems are discussed. (C) 1997 Elsevier Science B.V.