INTERSPECIFIC INTERFERENCE FOR NEST SITES BETWEEN LEPTOTHORAX-CONGRUUS AND MONOMORIUM-INTRUDENS

Interference competition for nest sites was studied in ant communities dominated by Leptothorax congruus in the suburbs of Tokyo, central Japan. At the two study plots located in a deciduous wood and in grassland, L. congruus constructed nests in dead branches or stems of dead grasses. Approximately 50% of the nests were physically broken within a year, suggesting that they were very fragile. Of totals of 67 and 91 nests of L. congruus marked at the two sites, 12 (17.5%) and 53 (58.2%) nests, respectively, were replaced by other ant species (Monomorium intrudens, Crematogaster brunnea teranishii, Camponatus itoi and Lasius sp.) which were common in both habitats. Field observation suggested that, among these ants, M. intrudens was a major competitor usurping the nests of L. congruus by aggressive invasion.