Volume 11 - 2016

Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/16684

Browse

Search Results

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Geographic Records of Subfamilies, Genera and Species of Ants (Hymenoptera: Formicidae) In The Four Climatic Zones of Sri Lanka: A Review
    (University of Kelaniya, 2016) Dias, R.K.S.; Rajapaksa, R.P.K.C.
    Ants are a major biotic component in the terrestrial environment of Sri Lanka. For the first time, geographic records of worker ants from the surveys conducted in the four climatic zones of Sri Lanka from 1999 to 2016 have been summarized. Geographic records of subfamilies, genera and 95 species of ants from variety of localities in each climatic zone were pooled and tabulated for each taxon. Among the 11 subfamilies, Amblyoponinae, Dolichoderinae, Formicinae, Myrmicinae, Ponerinae and Pseudomyrmecinae were common to the lands in the four zones while each of the other subfamilies were recorded from a single zone or two or three zones only. The Sri Lankan Relict Ant in Aneuretinae has many records in the wet zone and two records in the intermediate zone. Twenty two among 64 ant genera were recorded from the four climatic zones; 42 genera were found in a single zone or two or three zones. Recorded occurrence of each of the 95 species showed that 24 including 8 invasive species, Anoplolepis gracilipes, Monomorium pharaonis, Paratrechina longicornis, Solenopsis geminata, Tapinoma melanocephalum, Technomyrmex albipes, Tetramorium bicarinatum and Trichomyrmex destructor were common to the four zones. Further surveys on ants of Sri Lanka are highly recommended for improving the current knowledge on their occurrence and to provide information on the distribution of endemic and invasive ant species in Sri Lanka.
  • No Thumbnail Available
    Item
    Five Layered FCC Ferromagnetic Films as Described by Modified Second Order Perturbed Heisenberg Hamiltonian
    (University of Kelaniya, 2016) Samarasekara, P.; Warnakulasooriya, B.I.
    For the first time, the 2nd order perturbed Heisenberg Hamiltonian with all the seven magnetic energy parameters was solved for fcc structured ferromagnetic films with five layers. Previously, the 2nd order perturbed Heisenberg Hamiltonian was solved for four layered ferromagnetic films under some special assumptions by us. However, the exact solution of 2nd order perturbed Heisenberg Hamiltonian without any special assumption is formulated in this manuscript. The magnetic easy and hard directions were determined using the angles corresponding to the energy minimum and maximum in the 3-D and 2-D plots. The shape of the 3-D plots doesn’t change with the number of layers except the position of spikes. However, the magnetic easy direction varies with the number of layers. Most of the theoretical data obtained by our model agree with the experimental data of ferromagnetic thin films.
  • No Thumbnail Available
    Item
    Species richness of arboreal ant assemblages (Hymenoptera, Formicidae) and frequency of Oecophylla smaragdina (Fabricius) occurrence in a wet zone cashew (Anacardium occidentale L.) field in Sri Lanka
    (University of Kelaniya, 2016) Dias, R.K.S.; Perera, A.P.S.
    Ant assemblages on cashew trees in the wet zone of Sri Lanka were recorded throughout three phenological phases from March to June in 2015. Baited trapping and hand collection recorded fourteen ant species in five subfamilies and species richness observed on each occasion ranged from 7 to 11. Absence of serious cashew pests was noticeable in the current phenological cycle. Oecophylla smaragdina (Fabricius) was the only species recorded on all trees. Number of O. smaragdina nests observed on the same cashew trees in the two plots was recorded from April to June in 2015 and nests of the species were observed only on large and medium-sized trees. The materials carried by O. smaragdina workers on cashew tree branches were also collected, preserved in 70% ethanol and identified as far as possible using a Low Power Stereo-microscope and various plant and animal materials carried by workers confirmed that the species is an omnivore and a generalist predator. In the current study absence of serious damages caused by the cashew insect pests even without any insecticide application might be due to the presence of ant assemblages on cashew trees.