Pesticide use on cereal crops and changes in the abundance of butterflies on arable farmland in England.

Abstract

A survey of butterfly numbers on two plots of arable farmland in southern England in 1984 was carried out using the transect method of Pollard et al. (1975). On one plot the field edges were left unsprayed with pesticides (herbicides, fungicides and insecticides) from 1 January and on the other all fields were fully sprayed in accordance with normal farming practice. Sprayed and unsprayed transect sections were paired up according to adjacent field boundary habitat type.

A total of 868 butterflies were recorded on the unsprayed plot compared to 297 on the sprayed plot. Of the 17 species recorded on more than one survey section, 13 were significantly more abundant on the unsprayed treatment. Butterfly species whose larval host plants occurred in unsprayed field edges showed slightly larger differences in number between treatments than species less able to breed in weedy cereal crops.

The results suggest that pesticide use on cereal crops may reduce butterfly numbers and that arable farmland is a habitat in need of further study for butterfly conservation.