Arthropods in cereal crops: nocturnal activity, vertical distribution and aphid predation.

Abstract

The daily rhythms of activity of arthropods have been studied both in the air (Williams 1935; Lewis & Taylor 1965) and on the ground (Williams 1959, 1962; Greenslade 1963); however, little is known about the nocturnal activity of arthropods in cereal crops.

Some day-time observations suggest that predators such as Araneae and Stahpylinidae are scarce on cereal plants (e.g. Dean 1974) but these can be misleading if such arthropods are only active and/or present on the vegetation at night. Similarly, predation by some species may be underestimated if feeding is nocturnal and sampling diurnal.

The following is a preliminary study on the nocturnal activity and vertical distribution of some arthropods in cereal crops. In addition, the role of some species as aphid predators is considered. The work forms part of a wider study on the ecology of cereal crops which includes the role of predators and parasites in reducing populations of cereal aphids (Potts & Vickerman 1974).