Investigations on the ecology of Laemostenus terricola (Coleoptera, Carabidae) in an agricultural landscape

Summary

A large population of the cavernicolous species Laemostenus terricola (Herbst) living in an old hedge habitat within an intensively cultivated landscape about 30 km to the west of Bonn was studied with pitfall traps and other methods. Surface activity of L. terricola was not restricted to certain periods of the year. The results obtained indicate that the species is eurychronous with larval development during spring and summer. The main occurrence of teneral beetles and maximum activity of mature beetles was recorded in the second half of August and in September. Climatic parameters that correlated with fluctuations of catch numbers were nightly cloudiness and air humidity. It is discussed whether increased nocturnal light intensity under a clear sky may decrease the activity of the species.

The spatial distribution of L. terricola in the study area was significantly linked to that of rabbit burrows. Catch numbers correlated best with the closest distance to a rabbit hole. The amount of dead wood and litter on the soil surface were of no significance for this species. Results of mark-recapture experiments indicate that dispersal of L. terricola is low.

The preconditions to maintain populations of this species in agricultural landscapes are discussed.