Foraging by the carabid Agonum dorsale in the field

Abstract. 1. Small arenas in the field were used for observing adult Agonum dorsale (Pont.) foraging in a wheat crop.
2. The carabid showed no significant change in behaviour between low and high aphid density arenas.
3. Individuals foraged nocturnally and spent most of their time on the ground searching for prey. They climbed infrequently and then not high enough to reach aphid aggregations on the ears and flag leaves of wheat.
4. Gut dissection showed that more individuals had eaten aphids in the high aphid density arena than the low. Recording of aphid distribution within the arenas showed that this increase in aphid consumption could be explained by A.dorsale capturing aphids on the ground. Prey availability per unit area was in fact higher on the ground than on the wheat.
5. The contribution of ground-zone predators such as A.dorsale to the control of cereal aphids will be determined by the frequency with which aphids arrive on the ground and the proportion of these which reclimb the wheat and reproduce in the absence of predation.