Ground-dwelling ant assemblages (Family: Formicidae) in six coconut (Cocos nucifera L. 1753) plantations in Sri Lanka

The contribution of six well-established coconut plantations to the conservation of biodiversity, specifically of ants, was investigated using soil sifting, timed hand collection and honey baiting along five, 100 m transects established in each plantation. Twenty honey-baited pitfall traps were set throughout each sampling area of each plantation. Collected worker ants were preserved in 70% ethanol and sorted and identified to the furthest possible taxonomic levels under a low-power stereo-microscope. The ant species observed at the five transects in each plantation were tabulated and species richness and proportional abundance of each species at each plantation were recorded. The Shannon-Wiener Diversity index for the ant assemblage at each plantation was calculated. Air and soil temperature, soil humidity and soil pH at each locality were also measured. A diverse ant assemblage occurred at each plantation, where between 19 and 29 species in 4 or 5 subfamilies were recorded; the Shannon-Wiener diversity index values were determined. Higher proportions of formicines and myrmicines than those of other subfamilies were observed. Two or more species in higher proportions than the rest of the ants occurred in each assemblage. Also, the six plantations shared three species and five plantations shared nine species in common. The considerable diversity of ants indicated a healthy environment and provided insight into the presence of other animals in the well-established coconut plantations.