Browsing by Author "de Silva, C.S."

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Chlorpyrifos causes decreased organic matter decomposition by suppressing earthworm and termite communities in tropical soil
(Environmental Pollution, 2010) Mangala, P.; de Silva, C.S.; Pathiratne, A.; Nico M. van Straalen,; Gestela, Cornelis A.M. van
Effects of pesticides on structural and functional properties of ecosystems are rarely studied under tropical conditions. In this study litterbag and earthworm field tests were performed simultaneously at the same tropical field site sprayed with chlorpyrifos (CPF). The recommended dose of CPF (0.6 kg a.i. ha−1) and two higher doses (4.4–8.8 kg a.i. ha−1) significantly decreased litter decomposition during the first 3 months after application, which could be explained from lower earthworm and termite abundances during this period. Species-specific effects of CPF on organism abundance and biomass were observed, with termites being mostly affected followed by the earthworm Perionyx excavatus; the earthworm Megascolex sp. was least affected. Recovery was completed within 6 months. Decomposition in the controls and lowest two treatments was completed within 4 months, which suggests the need for modification of standard test guidelines to comply with faster litter degradation under tropical conditions.
Effect of mulch on tomato (Solanum lycopersicum) exposed to temperature and water stress
(Department of Zoology and Environmental Management, University of Kelaniya, 2015) Dishani, P.T.N.; de Silva, C.S.
Farmer’s perception on climate change and water availability: a case study in selected areas of Anuradhapura district
(Department of Zoology and Environmental Management, University of Kelaniya, 2015) Dishani, P.T.N.; de Silva, C.S.
Information Technology education in the Sri Lankan school system: Challenges and perspectives
(Sabaragamuwa University of Sri Lanka, 2006) de Silva, C.S.
Toxicity of chlorpyrifos, carbofuran, mancozeb and their formulations to the tropical earthworm Perionyx excavates
(Applied Soil Ecology, 2010) Mangala, P.; Pathiratne, A.; Cornelis, A.M.; Gestela, V.; de Silva, C.S.
Effects of chlorpyrifos, carbofuran, mancozeb and their formulated products on survival, growth and reproduction of the tropical earthworm Perionyx excavatus were investigated in standard artificial soil. The toxicity of the three chemicals decreased in the order carbofuran > chlorpyrifos > mancozeb. In general, formulations were more toxic than the active ingredients, but differences in LC50 and ECx values were significant only in two cases and not more than a factor of 2.0. This could mainly be due to masking of the effects of additives in the soil. Comparison with available survival data revealed that P. excavatus is more sensitive than the standard test species Eisenia andrei or E. fetida. The use of tropical species in the risk assessment of pesticides in tropical regions should therefore be encouraged.