The carabid and staphylinid fauna of winter wheat and fallow on a clay with flints soil.
Studies were carried out in Hertfordshire, England, during 1971-75 on the carabid and staphylinid fauna in areas of a Stackyard field (clay with flints) that were either planted with winter wheat or left fallow. Pitfall-trap collections showed that populations were altered by both immigration and emigration. After harvest, when the soil was ploughed and left fallow for a year, the activity of the beetles decreased as the temperature dropped and day-length shortened, and during December-March, larvae mostly replaced adults in trap collections. During May more beetles were caught in the crop area, where there was more food and shelter, than in the fallow area, indicating a movement from the uncropped to the cropped land. Agonum dorsale (Pontoppidan), Loricera pilicornis (F.), Philonthus spp. and Tachinus rufipes (Deg.) were almost entirely confined to the crop area, Pterostichus melanarius (Ill.), P. madidus (F.), Amara spp., Nebria brevicollis (F.) and Acupalpus meridianus (L.) were commoner in the crop area, and Trechus quadristriatus (Schr.), Clivina fossor (L.), Bembidion lampros (Hbst.) and Notiophilus biguttatus (F.) were often commoner in the fallow area. The index of diversity ( alpha ) for the beetle population in the crop area was lower in 1972, 1973 and 1975 than in 1971 and 1974; in all years except 1975, the diversity was similar in the fallow and crop areas. Temperature had the greatest effect on P. melanarius and Harpalus rufipes (Deg.). The position of traps with reference to the edge of the crop did not usually affect the numbers of beetles taken; however, traps nearest the edge with a hedge took more examples of Agonum dorsale in May 1975 and more examples of Nebria brevicollis in September and October 1973.