Validation of the use of pitfall traps to study carabid populations in cereal field headlands.

Abstract

Carabid populations from three cereal headland treatments were compared using pitfall traps and absolute density estimates obtained by mark-release-recapture and trapping out of enclosures.
The capture efficiency of individual species in pitfall traps was evaluated in the laboratory. Efficiency varied from 25% to 60% and a significant difference was found between species .
Cereal field headland treatments differed greatly in vegetation density, species composition and structural complexity. The activity of selected species was therefore compared in each of the three treatments, but did not differ significantly.
Pitfall trap data were only found to reflect density estimates by mark-release-recapture for Pterostichus melanarius. This suggested that pitfall traps reflected changes in activity not abundance.
Population density estimates made from population enclosures within barriered plots over the whole field season were only weakly correlated with pitfall trap catches. However such seasonal pitfall trap data gave an indication of headland treatment preference by carabids.
The validity of using pitfall traps to study carabid populations in cereal field headlands is discussed.