Chemistry
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/3748
Browse
35 results
Search Results
Item Bioactivity of leaf volatiles of Azadirachta indica A. Juss. and Murraya koenigii Spreng. against Sitophilus oryzae L.(Coleoptera: Curculionidae)(National Science Foundation of Sri Lanka., 2002) Paranagama, P.A.; Abeysekera, K.H.T.; Nugaliyadde, L.; Abeywickrama, K.Repellent activity, fumigant and contact toxicities of leaf volatiles of Azadirachta indica A. Juss. and Murraya koengii Spreng. were evaluated against Sitophilus oryzae L. In the dual choice repellency test with A indica leaf volatiles, significantly higher number of insects was repelled at doses above 100 mg, whereas volatiles of At. koenigii attracted insects at 25 mg dose and repelled at 300 mg dose. In the fumigant toxicity test 100% mortality was observed at the concentration of 32.5 mg/ml, 3 days after the treatment with 2 volatiles separately. The L C n values for fumigant toxicities were 13.5 and 22.5 mg/ml for A. indica and At. koenigii volatiles, respectively. In contact toxicity test, 100% mortality was observed immediately after 48 h contact exposure of insects at concentrations of 0375 and 0.125 mg/cm1 of A indica and At. koenigii respectively. The respective L C W values were 0.12 and 0.08 mg/cm1 for A. indica and At. koenigii leaf volatiles.Item Repellency and toxicity of four essential oils to Sitophilus oryzae L. (Coleoptera: Curculionidae)(2004) Paranagama, P.A.; Abeysekera, K.H.T.; Nugaliyadde, L.; Abeywickrama, K.P.Item Effect of the essential oils of Cymbopogon citratus, C. nardus and Cinnamomum zeylanicum on pest incidence and grain quality of rough rice (paddy) stored in an enclosed seed box(WFL Publisher, 2003) Paranagama, P.A.; Abeysekera, T.; Nugaliyadde, L.; Abeywickrama, K.P.The protective effect of the essential oils of Cymbopogon citratus, C. nardus and Cinnamomum zeylanicum leaf on paddy stored in wooden boxes lined with aluminium foil were evaluated. After 168 days of storage in oil treated boxes Sitotroga cerealella population was significantly lower in oil treated paddy than the control. The 1000 grain weight was higher in all three treatments (21.1 - 22.9 g) compared to the control (19.8 g). Percentage grain damage was lower in C. citratus and C. nardus treated paddy than the control. The percentage seed germination was not significantly different from that of the control in oil treated paddy though, in C. citratus treatment the seed germination was reduced. The milling quality of paddy was not affected by the essential oil treatment however; the flavour and stickiness of cooked rice was enhanced when treated with C. zeylanicum and C. citratus oils.Item Fungicidal and anti-aflatoxigenic effects of the essential oil of Cymbopogon citratus (DC.) Stapf. (lemongrass) against Aspergillus flavus Link. isolated from stored rice(The Society for Applied Microbiology, 2003) Paranagama, P.A.; Abeysekera, K.H.T.; Abeywickrama, K.P.; Nugaliyadde, L.Aims: To develop a natural fungicide against aflatoxigenic fungi, to protect stored rice, using the essential oil of lemongrass. Methods and Results: Aspergillus flavus Link. was isolated from stored rice and identified as an aflatoxigenic strain. Lemongrass oil was tested against A. flavus and the test oil was fungistatic and fungicidal against the test pathogen at 0Æ6 and 1Æ0 mg ml)1, respectively. Aflatoxin production was completely inhibited at 0Æ1 mg ml)1. The results obtained from the thin layer chromatographic bioassay and gas chromatography indicated citral a and b as the fungicidal constituents in lemongrass oil. During the fumigant toxicity assay of lemongrass oil, the sporulation and the mycelial growth of the test pathogen were inhibited at the concentrations of 2Æ80 and 3Æ46 mg ml)1, respectively. Conclusion: Lemongrass oil could be used to manage aflatoxin formation and fungal growth of A. flavus in stored rice. Significance and Impact of the Study: Currently, fungicides are not used to control fungal pests or mycotoxin production on stored rice. Rice treated with the essential oil of lemongrass could be used to manage fungal pests as well as the insect pests in stored rice. The essential oil is chemically safe and acceptable to consumers, as synthetic chemical fungicides can cause adverse health effects to consumers.Item Effect of volatile constituents of Curry leaf, Murraya koenigii on cowpea seed bruchid, Callosobruchu smaculatus (F.) in stored cowpea(University of Kelaniya, 2001) Adhikari, A.A.C.K.; Paranagama, P.A.; Bandara, K.A.N.P.; Abeywickrama, K.P.Item Insecticidal and repellent activity of volatile constituents of neem leaf (Azadirachta indica) against Callosobruchus maculatus(L.) inhabiting stored cowpea(Sri Lanka Association for the Advancement of Science, 2001) Paranagama, P.A.; Adhikari, A.A.C.K.; Abeywickrama, K.P.; Bandara, K.A.N.P.Item Effect of the essential oil of Cymbopogon nardus on Aspergillus flavus Link isolated from Sri Lankan paddy and rice(University of Kelaniya, 2002) Paranagama, P.A.; Abeysekera, K.H.T.; Nugeliyadde, L.; Abeywickrama, K.P.Item The efficacy of methanol extracts of leaves of lemongrass- Cymbopogon citratus (DC) Stapf and Curry leaf – Murraya koinigii Spreng on Callosobruchus maculatus(Proceedings of Sri Lanka Association of Advancement of Science, 2002) Paranagama, P.A.; Adhikari, A.A.C.K.; Abeywickrama, K.P.; Bandara, K.A.N.P.Item Bioactivity of leaf volatiles of Azadirachta indica A. and Murraya koenigii (spreng) against Sitophilus orysae (L.) (Coleoptera: Curculionidae)(Tropical Agricultural Research and Extension, 2002) Paranagama, P.A.; Abeysekera, K.H.T.; Nugeliyadde, L.; Abeywickrama, K.P.Item Repellant Activity of Alpinia calcarata Volatiles for Periplanata americana (American Cockroaches)(Asian Symposium on Medicinal Plants, Species and Other Natural Products, 2000) Paranagama, P.A.; Ekanayake, E.M.K.S.