Junior Research Symposia
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Item Arthropod diversity in four different ecosystems in the Mid Country Wet Zone of Sri Lanka(Department of Zoology and Environmental Management, University of Kelaniya, Sri Lanka, 2017) Weerathunga, W.A.M.T.; Athapaththu, A.M.G.K.; Amarasinghe, L.D.Arthropods contribute significantly to biodiversity of natural environments. The present study was done to determine the diversity of arthropods in four ecosystems with different vegetation. Vegetation surrounding an aquatic environment (AQ), a broad-leaved wet, evergreen forest ecosystem (BL), a Pinus caribaea monoculture plantation (PN) and a Pinus plantation artificially enriched with indigenous broad-leaved tree species (PNEN) located close to each other in Peradeniya were selected. In each environment, arthropods were sampled in three randomly-selected sites (5m x 5m) using four sampling methods, namely, pit-fall traps, sticky traps, sweep net and beating tray. Collected arthropods were identified upto the highest possible taxa using standard identification keys, based on morphological characteristics. Simultaneously, a plant census was conducted. Arthropod- and vegetation diversities were computed separately for each site using Shannon-Wiener Index (H). A total of 324 arthropod individuals were collected from all four sites. (AQ–71, BL–44, PN–20, and PNEN–189).They belonged to 68 species and 43 families. A total of 4416 plants were observed, from 84 species and 42 families. AQ had the greatest arthropod diversity (H=2.642), dominated by Olios spp. (Family Sparassidae) followed by BL (H=2.444), dominated by three arthropods, namely, a tettigonid species, Oxytate spp. (Family Thomisidae), and Psechrus spp. (Family Psechridae). PN had the next highest arthropod diversity (H=1.411), dominated by Dicaldispa spp. (Family Chrysomelidae). The lowest arthropod diversity was found at PNEN (H=1.3500), dominated by a formicid species. In contrast when considering plant diversity, PNEN had the highest diversity (H=2.614) and PN the lowest (H=0.879). AQ (H=1.810) and BL (H=1.871) had intermediate values. The arthropod diversity of AQ and BL was not significant from each other, while AQ was significant from the other two (F=5.50, P=0.024). PN and PNEN were not significant from each other. It was observed that in AQ, BL and PN the arthropod diversity was linearly dependent on plant diversity (R2=0.423) whereas it was not so when PNEN was also included (R2=0.008). This shows that higher plant diversity contributes to greater arthropod diversity in ecosystems where human intervention is minimum. But this pattern was not visible in PNEN, which is an artificially-created ecosystem.Item Preliminary study on carrion frequenting blowflies (Calliphoridae) in three localities in Sri Lanka and their response to formalin treatment(Department of Zoology and Environmental Management, University of Kelaniya, Sri Lanka, 2017) Athapaththu, A.M.G.K.; Amarasinghe, L.D.; Weerathunga, W.A.M.T.It is a known fact that formalin is unwarrantedly used to keep harvested fish longer in fresh condition. In this experiment, it was considered how it affects the natural population of blowflies by adding different concentrations of formalin to fish. Diversity of carrion attracting blowflies and its variation with the time was also quantified. Sardinella melanura fish were used. Three different concentrations of formalin (0.1 ppm, 0.01 ppm and 1 ppm) were injected (1.5 mL each) to three fish of same dimensions. The selected concentrations are highly likely to represent the range used by fisherman as 0.1 ppm is considered to be the minimum detectable by human senses. The fish were set in a water bottle bait trap, which were set in two environments (rural and suburban) at mid-elevation (149 m) and in two elevations (mid- and low, 7 m) in suburban environment. Carrion flies were collected daily. They were identified upto species level using pictorial keys, under stereo microscope. A total of 135 blowflies were collected. Cochliomyia spp. (Family Calliphoridae) was the most abundant type of carrion attracting blowfly in all three localities. In addition, housefly (Family Muscidae) was found only from the two suburban elevations. Blowfly diversity in the three localities was calculated separately, using Shannon-Wiener Index (H). The highest diversity was observed in low-elevation, suburban environment (H=1.211) followed by mid-elevation, suburban (H=0.889) and mid-elevation, rural environments (H=0.411) respectively. Availability of a source of blowflies in the neighborhood and favorable conditions to complete their life cycle can be reasons for higher diversity in the suburban environment. However, diversity did not vary significantly (p=0.05) with concentration of formalin injected, with H ranging from 0.938 to 0.983. Multiple regression analysis showed that the cumulative number of blowflies attracted increased with increasing formalin concentration. This could be due to increased concentration of formalin derived from breakdown of nitrogenous compounds as fish rot, plus the added formalin and genetic adaptation of blowflies. The number of blowflies attracted decreased significantly with increasing days after injection because with time the flesh is decomposed and the compounds which attract blowflies are gradually broken down.