Browsing by Author "Fernando, K.S.S.D."

Filter results by typing the first few letters
Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Discovery of three new Tetraponera species (Formicidae; Pseudomyrmecinae) from Sri Lanka.
    (International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Dias, R.K.S.; Udayakantha, W.S.; Thotagamuwa, A.; Fernando, K.S.S.D.; Madushani, N.
    Tetraponera F. Smith is the sole genus of subfamily Pseudomyrmecinae recorded from Sri Lanka and very little is known about the diversity of the arboreal genus in the country. Nests of Tetraponera species were collected by checking the worker trails and locating them followed by severing the nests from the host trees. Colony members in (i) a nest in a cashew tree branch from Delgoda (7º 00.395´N and 80º 00.96´E) Udupila in Gampaha District in March, 2015 (ii) three nests of Tetraponera from two jack trees in the premises behind the Department of English language Teaching (6º58´ 35.94" N and 79º54´ 58.8"E), University of Kelaniya in March, 2015 and (iii) a nest in a dry rubber branch from Gulanakanda (6°35'01.7"N 80°00'36.7"E), Bombuwala, Kalutara in August, 2016 were preserved in 70 % ethanol for the identification and listing of Tetraponera species. Fifteen morphometric parameters of each adult caste of each species, if present, were measured using a calibrated micrometre eyepiece fixed to a stereo-microscope and total length of the adult castes were measured by a ruler in mm scale, which was kept under the stereo-microscope. Cephalic Index (CI=HW/HL), Scape Index (SI=SL/HW) and Relative Eye Length (REL=EL/HL) were also calculated. Worker ants were identified to the species level refering to the relevant literature; T. extenuata Ward, T. microcarpa Wu and Wang and T. modesta (F. Smith) in Tetraponera allaborans-group were identified from the nests (i), (ii) and (iii), respectively. Black or dark brownish black worker with the contrasting brownish orange post-petiole, tibiae, tarsi and scapes, taller and more slender propodeum and more convex and soft-edged pronotal margins characterized T. extenuata workers. Workers of T. microcarpa were of black or brownish black, with lighter brown petiole, post-petiole and appendages, bidentate median clypeal lobe, short and broad profemur and quadrat-shaped propodeum. Small size, orange-brownish colour of the body with lighter colour appendages and relatively slender profemur characterized T. modesta workers. Colony demography of each nest recorded by counting the number of each adult caste with the naked eye and that of larvae, pupae and eggs under the stereo-microscope indicated that workers generally had the highest percentage abundance whereas eggs or larvae were also present in higher percentages. Very low percentage of dealate queen was observed in each nest. Four Tetraponera species, T. rufonigra (Jerdon), T. allaborans (Walker), T. nigra (Jerdon) and T. nitida (Smith) recorded previously from Sri Lanka rose to seven with the current findings. A taxonomic key that distinguish all Tetraponera species recorded from Sri Lanka is prepared with the colour images to facilitate quick identification of workers of each species.
  • Thumbnail Image
    Item
    Effects of kerosene and citronella oil on the worker ants of Tetraponera rufonigra Jerdon (Formicidae, Pseudomyrmecinae), a medically important ant species, in tropical Asia
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Dias, R.K.S.; Fernando, K.S.S.D.
    Serious medical conditions due to sudden outbreaks of Tetraponera rufonigra and increase of its stings in urban localities were reported recently in Sri Lanka. Control methods appropriate for suppressing T. rufonigra workers in such situations were investigated using kerosene or citronella oil in the laboratory. Toxicity tests were conducted with appropriate control experiments and in three replicates, by applying 10 μl, 12 μl, 14 μl, 16 μl, 18 μl and 20 μl of citronella oil on dorsal prothorax of each of the acclimatized ten workers used in each treatment. Number of dead ants observed with each treatment was recorded after 10 minutes of each application. Probit analysis performed with the percentage mortality of workers resulted 6.38 mg/mg body weight of ant of citronella oil as LD99 of the workers. For field simulating experiments, citronella oil containing (100%) sprayer bottle and a common hand sprayer were bought and spray volume of each sprayer was calculated. Increasing volumes 0.6 ml, 1.2 ml, 1.8 ml, 2.4 ml and 3.0 ml of kerosene or 0.64 ml, 1.28 ml, 2.56 ml, 3.84 ml and 5.18 ml citronella oil based on the calculated spray volumes, were applied separately to ten acclimatized workers in a plastic bottle in three replicates; time period until ten worker ants died since spraying was recorded for each treatment. Appropriate control set up was maintained for each treatment. Spraying of 3.0 ml of kerosene or 5.2 ml of citronella oil, as minimum volumes, is recommended for the temporary suppression of ten worker ants.
  • Thumbnail Image
    Item
    Functional morphology of the sting apparatus of Tetraponera rufonigra (Smith, F.) (Formicidae, Pseudomyrmecinae)
    (Department of Zoology and Environmental Management, University of Kelaniya, 2015) Fernando, K.S.S.D.; Dias, R.K.S.; Rajapaksha, R.P.K.C.
  • Thumbnail Image
    Item