Species composition and diversity of ant fauna (Hymenoptera: Formicidae) observed throughout a Yala season growing cycle of paddy fields in Gampaha District, Sri Lanka

Abstract

Rice fields are inhabited by a great variety of fauna including ants. Species composition, proportional abundance and species diversity of ant fauna in two, similar rice fields in Mahadarawa, Gampaha District of Sri Lanka were investigated by honey baiting, hand collection and pitfall trapping conducted along four, 20 m transects throughout a Yala season growing cycle of paddy and 11 species in 11 genera of 4 subfamilies were observed in the two fields. Nine species were recorded during all stages of the rice fields whereas Anochetus graeffei Mayr, 1870 and Monomorium floricola (Jerdon, 1851) were not recorded in the seedling stage. The methods that caught species varied with the stage of the field. Overall, Tapinoma melanocephalum (Fabricius, 1793), Anoplolepis gracilipes (Smith, 1857) and Camponotus compressus (Fabricius, 1787) were observed in significantly higher proportions than other species. Shannon-Wiener Diversity Index ranged between 1.828–1.999 while Shannon-Wiener Equitability Index varied between 0.762–0.873 indicating a considerable diversity and less evenness in the ant communities recorded during the single growing cycle.

Keywords

• ants
• paddy fields
• yala season growing cycle
• wet zone
• sri lanka