Distribution and habitat preferences of tiger beetles (Coleoptera: Cicindelidae) of the riverine ecosystems of Sri Lanka

Abstract

Tiger beetles have been observed in many riverine ecosystems of Sri Lanka. However, current locations, species, distribution of species, habitat preferences and possible interactions between species are unknown. The present study intends to investigate these details and provide information that can be used in further studies. Tiger beetles are sampled from 15 riverine locations and examined for identification, body weight and body length. The riverine locations are analysed for locational, climatic and soil parameters and microhabitat details are recorded. Statistical analysis using One-Way Analysis of Variance and Tukey’s pair comparison method of Minitab 16.0 statistical software package is conducted to compare the body sizes of species. Further, a statistical comparison between the climatic and soil parameters of the locations of Cylindera (Ifasina) labioaenea and that of other species are carried out. The study reveals five tiger beetle species Cylindera (Ifasina) labioaenea Horn, Cylindera (Ifasina) willeyi Horn, Cylindera (Ifasina) waterhousei Horn, Calomera cardoni Fleutiaux, Calomera angulata Fabricius, from the riverine ecosystems of Sri Lanka. Cylindera labioaenea is the most common species; C. willeyi and C. waterhousei are endemic to Sri Lanka. Cylindera labioaenea, C. willeyi and C. waterhousei are small, while Calomera cardoni and Calomera angulata are medium in size. Cylindera labioaenea is significantly smaller than C. willeyi and C. waterhousei, and resides in locations with significantly higher air temperatures, solar radiations and significantly lower relative humidity than the other two species. An optimal temperature range for the riverine tiger beetles is suggested and their preferences to soil moisture, soil temperature, soil colour and soil salinity are discussed. The occurrence of C. labioaenea as a single species population while the fact that other species co-exist may be due to a defensive strategy.