Plasticity in Predation Behaviour of Carabid Beetles in Agro-Ecosystems

摘要

A study on the feeding behaviour of three species of Chlaenius and two species of Calosoma (Coleoptera: Carabidae), the caterpillar and semi-looper hunting predatory ground beetles in agro-ecosystems, was carried out under laboratory conditions in the Department of Entomology, Rajasthan College of Agriculture, MPUAT, Udaipur, during September to November, 2016. The carabid predator species and the second/ third instar tobacco caterpillar prey relationship followed the typical Holling’s Type II functional response. Of the three species of Chlaenius evaluated, Chlaenius udaipurensis Chanu and Swaminathan consumed the maximum prey with a preference for the second instar tobacco caterpillar. Increase in second instar caterpillar prey density from 1 to 5 resulted in an increase in mean prey consumption up to 4.4 in 24 hours. Under enhanced prey provision from 5 to 25 to Ch. udaipurensis the maximum mean consumption was 9.0; whereas, the maximum third instar caterpillar consumption was only 2.0 in 24 hours. Both species of Calosoma could kill 11 to 13 third instar tobacco caterpillars per day. Increased prey density evinced a gradual decreasing trend in the per cent feeding propensity with little variation among the species for both the genera of carabids. The relationship between prey consumption and the body mass increase for the species of Chlaenius showed significant positive correlation (r = 0.902 for II instar prey and r = 0.711 for III instar prey); similarly, the relationship for Calosoma species had significant positive correlation (r = 0.795).