International Research Symposium on Pure and Applied Sciences (IRSPAS)
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Item Contarinia maculipennis as an emerging threat to Dendrobium in Sri Lanka - A case study.(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Dias, M.A.; Amarasinghe, L.D.; Jayalath, W.G.H.; Attanayake, R.N.Blossom midge, Contarinia maculipennis which belongs to Order Diptera: Family Cecidomyiidae is considered as one of the major threat to ornamental and several crop plant species due to its wide host range. For the first time C. maculipennis was recorded from Dendrobium sp. in 1992 from Florida, but the origin of this species is considered as Southeast Asian region. In Korea, it is officially nominated as a quarantine pest since 2007 due to it’s sever economic impact on vegetable crops and ornamental plants. For the first time in Sri Lanka, completely damaged Dendrobium cultivation was found in an ornamental plant nursery at Gampaha district in 2017. It was noted that the symptoms were similar to that of blossom midge damage. Maggots were found to be feeding inside unopened flower buds, causing deformed, discolored buds and blossoms causing premature bud or blossom drop. Floral buds were often found to be rotted. Samples from immature bud stage to fully opened flowers were randomly collected from infected fields into polythene bags. To identify causative agent, floral buds with larval stages were kept in glass containers to allow them to complete their life cycle and thereby morphological characters were studied to confirm the pest species. In addition, yellow color grease sheets were kept inside the greenhouses to trap any adult stages of the pest species. Samples were collected and preserved using 70% ethanol for identification. Since all the damaged flower buds displayed symptoms of bacterial rots, to determine if any bacterial infection is also associated with the symptoms, bacterial isolation procedure was carried out. Different stages of floral samples were separately surface sterilized for two minutes using 70% ethanol and three serial washings with sterilized distilled water. Tissue macerate was prepared and kept for 3 hours before culturing on Nutrient Agar (NA) plates, Potato Dextrose Agar (PDA) and Luria-Bertani (LB) plates. Each sample had three replicates and ten samples were cultured. Growth from the tissues were observed and pure cultures were obtained. Relative length of the first and second flagellomeres, wing length and pattern, larval sternal spatula and its associated papillae and larval eighth abdominal segments were compared with identification keys which were used to identify the genera, Contarinia. The adult stages of trapped insects and adult stages of insect immerged from the larval stages were useful in confirming the species as C. maculipennis. Basic biochemical tests and Gram’s staining assisted in identifying the bacterium as belonging to the genera, Erwinia sp. and it appears that the bacterial infection occurs as a secondary infection after larval stages of C. maculipennis damage the floral tissues. This is the first record of C. maculipennis infecting orchid nurseries in Sri Lanka and if proper care is not taken it will invade other crop species as the pest has a broad host range. It is not clear whether the pest was a recent introduction through the imports of plant material or whether it is a result of host jump and therefore, it warrants further research.Item A preliminary floristic study of Chundikulam forest reserve in Jaffna peninsula(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Ekanayake, G.C.M.; Medhavi, P.I.H.R.; Somasiri, R.P.I.V.; Jayalath, W.G.H.; Siriwardhana, K.H.W.; Samarasinghe, D.G.S.N.; Kannangara, S.Chundikulam sanctuary is a reserve which is located in the Northern Province, in Jaffna peninsula. This reserve is situated in the dry zone of Sri Lanka and the area consists of mangroves along the shores and scrub lands in the sandy areas. The Jaffna peninsula, including Chundikulam, faced an ecological destruction due to the Sri Lankan civil war which prevailed for almost three decades. Therefore, due to the paucity of data of this arid vegetation, this current study was carried out as the first investigation after war. According to the surveys, Chundikulam covers an area of 19,000 hectares in vegetation. A systematic study on the vegetation of this dry arid zone forest was carried out using randomly selected representative sampling sites to document the vegetative diversity of the region, through a field survey conducted in the peripheral areas of this reserve in March 2016. Five quadrates (10m×10m) per site were placed totaling to 25 random sample collections. Eighteen different plant species were collected during the study and herbarium specimens were prepared and submitted to the Department of Botany herbarium, University of Kelaniya, Sri Lanka. The plant species sampled were trees (8 species), shrubs (4 species) and creepers (6 Species). Among them Carissa spinarum, Borassus flabellifer, Drypetes sepiaria, Stereosperum colais, Prosopis juliflora. Dillenia sp., Pterocarpus sp. were tree species and Atalantia ceylanica,and Memwcylon umbellatum were recorded as shrubs and Euphorbia antiquorum, Jasminum officinale, Hardenbergia sp. were identified as creepers. The dominant plant species of the vegetation was Drypetes sepiaria (Putranjivaceae) while Borassus flabellifer (Arecaceae) was the most abundant.The total vegetation cover was estimated by the mean number of individuals (30.4%). The plant communities that have been recognized in this study within the arid and dry forest in Chundikulam forest reserve will provide preliminary scientific data for a systematic review of the changes in their vegetation after the war which prevailed for almost three decades.