Browsing by Author "Perera, R. N. N."

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Assessing the substrate degradation specificity and life stage performances of black solider fly larvae (Hermetia illucens) in different bio-degradable waste substrates
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Magamage, M. P. S.; Ellawidana, D. M.; Perera, R. N. N.; Lakmini, P. K.; Priyadarshana, M. K. C.
Solid waste management has become decisive challenge in Sri Lanka where majority of the generated waste is dumped in an unsystematic way. It is highly encouraged to pursuit more reliable waste management methods in an effective way to mitigate this issue. The black solider fly (Diptera: Hermetia illucens) is a harmless insect proven for its larvae’s enormous bio-waste degradable ability and animal feed. This study intends to propose the most suitable substrate to breed the larvae by assessing substrate effect for the larval growth performance and substrate degradable specificity. Specially designed bin which facilitate brooding, aeration, leachate extraction and self-harvesting was used. As three different substrates, 100% swill (T1), 100% fish offal (T2) and rotten fruits and vegetables (T3) were used and maximum allowable height of 20 cm was marked inside the bin. Egg laying lap, eggs volume and length of egg masses, substrate consumption height, pH, average moisture % (wet/dry basis), temperature (inside /outside the substrate), length and width of different larval stages and larval proximate value (crude protein %) were recorded. During the egg laying and colonization period each bin was examined in two hours interval from 8.00 a.m. to 5.00 p.m. for two months. Once brooding initiated, new substrate was refilled by 1 kg in two day intervals. First eggs emergence sequence was recorded as T1, T2 then T3. There was no substrate dependent effect for the mean egg volume (0.97 eggs/mm3) and average egg length (895.389μm) in each bin using three replicates. The highest substrate consumption height was recorded in T1 (10.3 cm). Highest pH drop of the decaying substrates was recorded in T1 (5.82) where T2 (6.17) recorded the least pH drop of the substrate. On wet / dry basis, the highest moisture content was in T3 (20.04% and 25.06% respectively) whereas the lowest moisture level was in T2 (12.06% and13.71% respectively). The highest inner (37.1°C) and outer (30.9°C) substrate temperature was recorded in T1 and lowest value was recorded in T3. According to the larval growth performances, larval width and length were varying with respect to the larval stage. Larval crude protein % was highest in T3 (48.95%) and lowest in T1(33.06%). In conclusion, based on the mean comparison study 100% swill indicated the most favorable conditions for the larval growth whereas larvae grew in rotten fruits and vegetables were the most suitable substitute for animal feed as a protein source.
Implications of Fall Armyworm epidemic in Sri Lanka: A case study in Rathnapura district
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Perera, R. N. N.; Magamage, M. P. S.; Siriwardhana, C.
The first emergence of the Fall Armyworm (FAW; Spodoptera frugiperda) was reported in Sri Lanka during August 2018 and caused a substantial yield loss in maize cultivation especially in Uva, Eastern, North Central, North Western, Northern and Sabaragamuwa provinces. During the 2018/19 Maha season, over 50 percent of the entire maize cultivation has been infested by the pest. The objective of the study was to understand the magnitude of FAW infestation, social response and its implications in Rathnapura district in Sri Lanka. This was considered as mandatory in terms of easiness in accessibility to close supervision by the university as well as with the objective of preventing infestations reaching economically catastrophic levels. Simultaneously to the field inspection programme, a survey was conducted in January-March 2019 in 13 maize growing agriculture instructor (AI) areas in the Rathnapura district to evaluate the severity of FAW infestation with the collaboration of the Provincial Department of Agriculture, Sabaragamuwa Province. University academia, students, and field officers from Department of Agriculture were participated to the survey and all 13 divisions were covered for collecting pest incidence information. GIS data were recorded in each point of infestation together with related other information such as land extent, host plant characteristics and the type of cropping system which plays important role in forecasting the pest occurrence in the subsequent cropping season. Based on the field survey, there were no evidences reported that pest occurrence in other crops apart from maize. Moreover, even in mixed cropping systems with little number of maize plants, heavy infestation was recorded only in maize. Data analysis was done based on the primary land infestation records obtained from each AI range by using MS office Excel 2010. Amount of land extent use for maize cultivation in Rathnapura district was estimated as 292.65 ha, while 32.95ha were infected with the pest (11.3%). Kaltota, Embilipitiya, Ambawila and Thimbolketiya were the AI areas with highest infestation recorded in the Ratnapura District reporting 5%, 4.8%, 4.5% and 3.85 % infestations respectively. Throughout the study period, attention was made by the research team for minimizing livelihood damage by conducting interactive awareness programs, which were directed to proper identification and control further spread of the pest. Even though maize was cultivated comparatively lower land extent in Rathnapura, effective and organized disaster management response in Rathnapura was able to minimize the pest impact to 11.3% from total losses. Mobilization of the whole agriculture community has wider implications in effective controlling of FAW while preserve the farmer trust on agriculture policy in Sri Lanka.