The Carabid and Staphylinid Fauna of Winter Wheat and Fallow on a Clay with Flints Soil

Abstract

In a field of clay with flints where winter wheat and fallow alternated, the composition of the indigenous population of Carabidae and Staphylinidae was altered by immigration and emigration. After harvest, when the soil was plowed and left fallow for a year, the activity of Carabidae and Staphylinidae decreased as temperatures dropped and day lengths shortened, and during Dec. to March beetle larvae mostly replaced the adults in pitfall trap catches. During May more beetles were caught in the wheat crop where there is more food and shelter, than in the fallow land, indicating a movement from the uncropped to the cropped area. Some species, e.g., Agonum dorsale (Pont.), Loricera pilicornis (F.), Philonthus spp. Tachinus rufipes (Deg.) were almost entirely confined to the wheat; others, e.g., Pterostichus melanarius (Ill.), P. madidus (F.), Amara spp., Nebria brevicollis (F.) and Acupalpus meridianus (L.) were more common within the wheat than in the fallow; and a 3rd group Techus quadristriatus (Schr.), Clivina fossor (L.), Bembidion lampros (Herbst.) and Notiophilus biguttatus (F.) were often more active on the fallow. The index of diversity .alpha. for the crop was similar in 1971 and 1974 (18.9, 18.6) but dropped in 1972 and 1973 (14.2, 11.6) when adverse weather during periods of the year may have affected activity and was low in 1975 (11.5) when large numbers of Agonum dorsale migrated into the crop. Strawburning in Sept. 1972 probably reduced the food supply in the soil the following year (1973). Except in 1975, value for .alpha. from the fallow was similar to that from the crop. Correlation and regression analysis of beetles [loge (n + 1)] caught and accumulated temperature (above 5.degree. C threshold), sunshine and rainfall showed that temperature had the greatest effect on Pterostichus melanarius and Harpalus rufipes Deg. The position of the traps with reference to the edge of the crop did not usually affect the numbers of beetles caught except in May 1975 when those nearest the edge with a hedge caught more Agonum dorsale in Sept. and Oct. 1973 when they caught more Nebria brevicollis.