Volume 07 - 2012

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Pretreatments and Cold Storage on the Quality of Minimally Processed Ambarella (Spondias Dulcis L.) and the Mixed Load of Ambarella and Pineapple (Ananas Comosus (L.) Merr)
(University of Kelaniya, 2012) Daranagama, A.; Ediriweera, S.; Abeywickrama, K.P.
Minimally processed ambarella (Spondias dulcis L.) and the mixed load of ambarella and pineapple (Ananas comosus (L.) Merr) stored at 5-7 0C for seven days were evaluated for variation in physico-chemical, sensory and microbiological quality. Samples were treated with sodium chloride, calcium chloride, sodium chloride + calcium chloride, ascorbic acid, citric acid, chitosan or distilled water (control) and packed in polystyrene packages before storage. Pretreatments did not have a significant effect on the physico-chemical properties [titratable acidity (TA), total soluble solids (TSS) and pH] when compared to the control. Sensory attributes such as appearance, colour, odour, flavour, taste and overall acceptability generally declined with time but were within acceptable limits by the end of seven-day storage period. The microbial counts (total plate count and yeast and mould count) for all treatments except for the control were within safe-to-consume limits and Salmonella was not detected in any of the samples by the end of storage period. As pretreatments tested had no significant effect on physico-chemical or sensory properties and maintained low microbial counts, minimally processed ambarella and mixed load of ambarella and pineapple processed this way could be recommended for sale at supermarket chains with cold storage facility as a value added product.
Genetic Variation and Phytotoxin Production among Cylindrocladium. Quinqueseptatum Isolates of Hevea Brasiliensis and Eugenia Carryophyllata
(University of Kelaniya, 2012) Jayaratne, D.L.; de Silva, B.A.C.; Silva, W.P.K.
Cylindrocladium quinqueseptatum (Boedijn & Reitsma 1950) is one of the major plant pathogenic fungi that infects a wide range of plants in humid tropics. The prevailing strains in Sri Lanka cause the foliage and shoot blight diseases and severe defoliation of Hevea brasiliensis (rubber) and Eugenia carryophyllata (clove). The isolates obtained from rubber and clove plants growing in Rathnapura district, in Sabaragamuwa province and Kalutara district, in Western province were evaluated for their toxin activity on hosts and genetic characterization was done using random amplified polymorphic DNA Polymerase Chain Reaction (RAPD-PCR grouping). The analysis of the results using ‘Wilcoxon signed-rank test’ revealed no correlation among the isolates based on their host or geographical origins. But a relationship was observed between the toxin activity and the RAPD grouping of the isolates. The time course experiment reveled that the minimum toxin activity recorded after three days of inoculation and maximum toxin activity was recorded after nine days of inoculation in Modified Fries Medium (MFM) for all the isolates. Based on the toxin activity and genetic characterization data, the isolates were categorized into two groups. The close genetic relationship (similarity index = 0.731) and high toxin activity were shown by one group of isolates obtained from cloves grown in Rathnapura with other two groups of isolates obtained from rubber grown in Kalutara. This observation suggests that C. quinqueseptatum isolated from clove grown in Rathnapura can be a potential pathogen on rubber.
A Preliminary Inventory of Subterranean Termites in the Premises of Faculty of Science, University of Kelaniya and the Potential of a Ponerine Ant Species, Neemazal-F and Citronella Oil in the Control of Two Termite Species
(University of Kelaniya, 2012) Wijerathna, K.H.C.A.; Dias, R.K.S.
Termites are an important biotic component in terrestrial ecosystems and the termites in seven localities of the Faculty of Science of University of Kelaniya were investigated by employing soil sifting, litter sifting, hand collection, baited pitfall trapping and long term baits from September, 2008 to April, 2009. The collected termites were preserved in 80% ethanol. Soil temperature and pH, and percentage soil moisture at each location were also recorded. Members of Termitidae and Rhinotermitidae, Dicuspeditermes incola Wasmann, Heterotermes ceylonicus Holmgren, Nasutitermes ceylonicus Holmgren, Nasutitermes horni Wasmann, Odontotermes ceylonicus Wasmann, Odontotermes horni Wasmann and Trinervitermes rubidus Hagen, were recorded. Odontotermes horni had a wide distribution in the seven localities. The interactions between a common ponerine ant, Odontomachus simillimus F. Smith and O. ceylonicus Wasmann revealed that O. simillimus acts as a natural enemy of this termite species. Termiticidal potential of Neemazal-F and citronella oil on the soldiers and workers of O. horni was evident while LD50 values were 11.15 mg and 8.21 mg per body weight g-1 of each product, respectively.
Occurrence and Species Diversity of Ground-Dwelling Worker Ants (Family: Formicidae) in Selected Lands in the Dry Zone of Sri Lanka
(University of Kelaniya, 2012) Dias, R.K.S.; Kosgamage, K.R.K.A.
Ants are an essential biotic component in terrestrial ecosystems in Sri Lanka. Worker ants were surveyed in six forests, uncultivated lands and, vegetable and fruit fields in two Districts of the dry zone, Anuradhapura and Polonnaruwa, from November, 2007 to October, 2008 by employing several sampling methods simultaneously along five, 100 m transects. Soil sifting, litter sifting, honey-baiting and hand collection were carried out at 5 m intervals along each transect. Twenty pitfall traps were set up throughout each site and collected after five hours. Air and soil temperatures, soil pH and soil moisture at each transect were also recorded. Use of several sampling methods yielded a higher value for species richness than just one or two methods; values for each land ranged from 19 – 43 species. Each land had its own ant community and members of Amblyoponinae, Cerapachyinae, Dorylinae, Leptanillinae and Pseudomyrmecinae were recorded for the first time from the dry zone. Previous records of 40 species belonging to 23 genera in 5 subfamilies for the Anuradhapura District are updated to 78 species belonging to 36 genera in 6 subfamilies. Seventy species belonging to thirty one genera in 9 subfamilies recorded from the first survey of ants in Polonnaruwa lands can be considered a preliminary inventory of the District; current findings updated the ant species recorded from the dry zone to 92 of 42 genera in 10 subfamilies. Consequent to this sum, the estimate of ant diversity of Sri Lanka rises to 202 species in 64 genera while 12 subfamilies remain unchanged.