Carabid populations in field beans and their effect on the population dynamics of Sitona lineatus (L.)

SUMMARY The abundance and diversity of potential carabid predators of Sitona lineatus (L.) in field beans were monitored between 1980 and 1983. The absolute abundance of the large predatory species was determined in mark‐recapture experiments and a radio‐labelling technique was used to estimate the level of predation in the field. Using previously published population data for S. lineatus, the importance of predation in the population dynamics of the weevil was estimated. The mortality of weevil larvae due to predation varied from 0.6%– 10.5% while that of adult weevils varied from 2.6%– 23.8%. It appeared that carabids played a significant role in the population dynamics of S. lineatus and, in years when abundant, could reduce the population of larvae and overwintering adults by more than 30%.