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- Ashitani, Tatsuya, et al.
(författare)
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Activity studies of sesquiterpene oxides and sulfides from the plant Hyptis suaveolens (Lamiaceae) and its repellency on Ixodes ricinus (Acari:Ixodidae)
- 2015
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Ingår i: Experimental & applied acarology. - : Springer Science and Business Media LLC. - 0168-8162 .- 1572-9702. ; 67:4, s. 595-606
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Tidskriftsartikel (refereegranskat)abstract
- Hyptis suaveolens (Lamiaceae), a plant traditionally used as a mosquito repellent, has been investigated for repellent properties against nymphs of the tick Ixodes ricinus. Essential oils and volatile compounds of fresh and dried leaves, from plants originating from Laos and Guinea-Bissau, were identified by GC-MS and tested in a tick repellency bioassay. All the essential oils were strongly repellent against the ticks, even though the main volatile constituents differed in their proportions of potentially tick repellent chemicals. (+)/(-)-sabinene were present in high amounts in all preparations, and dominated the emission from dry and fresh leaves together with 1,8-cineol and alpha-phellandrene. 1,8-Cineol and sabinene were major compounds in the essential oils from H. suaveolens from Laos. Main compounds in H. suaveolens from Guinea-Bissau were (-)-sabinene, limonene and terpinolene. Among the sesquiterpene hydrocarbons identified, alpha-humulene exhibited strong tick repellency (96.8 %). Structure activity studies of oxidation or sulfidation products of germacrene D, alpha-humulene and beta-caryophyllene, showed increased tick repellent activity: of mint sulfide (59.4 %), humulene-6,7-oxide (94.5 %) and caryophyllene-6,7-oxide (96.9 %). The substitution of oxygen with sulfur slightly lowered the repellency. The effects of the constituents in the oils can then be regarded as a trade off between the subsequently lower volatility of the sesquiterpene derivatives compared to the monoterpenes and may thus increase their potential usefulness as tick repellents.
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| 3. |
- de Boer, Hugo J., et al.
(författare)
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A Fly in the Ointment : Evaluation of Traditional Use of Plants to Repel and Kill Blowfly Larvae in Fermented Fish
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:12
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: In rural areas in Laos, fly larvae infestations are common in fermenting fish. Blowflies (Chrysomyamegacephala, Diptera: Calliphoridae) are attracted to oviposit (and/or larviposit) onto fermenting fish which results ininfestations with fly larvae. Knowledge of traditional use of plants to repel larvae during the production of fermented fish iscommon and widespread in Lao PDR.Research Questions: How effective are the most salient species in repelling, and killing fly larvae in fermenting fish?Material and Methods: The three plant species most frequently reported to repel fly larvae during an ethnobotanical surveythroughout Lao PDR were tested for repellence and larvicidal activity of fly larvae infesting fermented fish. The lethality andrepellence of Tadehagi triquetrum (L.) H. Ohashi (Fabaceae), Uraria crinita (L.) Desv. ex DC. (Fabaceae) and Bambusa multiplex(Lour.) Raeusch. ex Schult. & Schult. f. (Poaceae) were tested in an experimental design using fermenting fish in Vientiane,Lao PDR.Results: The repellent effect of fresh material of T. triquetrum and U. crinita, and the larvicidal effect of fresh B. multiplex, issignificantly more effective than that of dried material of the same species, and the total effect (repellence and larvicidaleffect combined) for each of the three species was significantly more effective for fresh than for dry material. Fresh materialof T. triquetrum, U. crinita, or B. multiplex added on top of the fermenting fish repelled 50%, 54%, 37%, and killed 22%, 28%,and 40% of fly larvae. The total effect was not significantly different per species at 72%, 82%, and 77%, respectively.Discussion and Conclusions: The three most salient species are effective in repelling and killing fly larvae in the productionof fermented fish, and may be essential to augment food safety during traditional fermentation in open jars.
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| 4. |
- de Boer, Hugo J., et al.
(författare)
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Botanical Repellents and Pesticides Traditionally Used Against Hematophagous Invertebrates in Lao People's Democratic Republic : A Comparative Study of Plants Used in 66 Villages
- 2010
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Ingår i: Journal of medical entomology. - 0022-2585 .- 1938-2928. ; 47:3, s. 400-414
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Tidskriftsartikel (refereegranskat)abstract
- Hematophagous parasites such as leeches, ticks, mites, lice, bedbugs, mosquitoes, and myiasis-producing fly larvae are common health problems in Lao People's Democratic Republic. Several arthropod-borne infections, e.g., malaria, dengue fever, and Japanese encephalitis, are endemic there. Effective vector control methods including the use of pesticides, insecticide-treated bed nets, and synthetic and plant-based repellents are important means of control against such invertebrates and the pathogens they may transmit or directly cause. In this study, we documented traditional knowledge on plants that are used to repel or kill hematophagous arthropods, including mosquitoes, bedbugs, human lice, mites and ticks, fly larvae, and blood-sucking leeches. Structured interviews were carried out in 66 villages comprising 17 ethnic groups, covering a range of cultures, throughout Lao People's Democratic Republic. A total of 92 plant species was recorded as traditional repellents (including plants for pesticidal usages) in 123 different plant-ectoparasite combinations. The number and species of plants, and animal taxa repelled (or killed) per plant species differed per region, village, and ethnic group. Traditional use was confirmed in the scientific literature for 74 of these plant species, and for an additional 13 species using literature on closely related species. The use of botanical repellents and pesticides from many plant species is common and widespread in the Lao countryside. In the future, the identification of the active components in certain plants to develop more optimal, inexpensive repellents, insecticides, acaricides, or antileech compounds as alternatives to synthetic repellents/pesticides against blood-feeding insects, ticks, mites, and leeches is warranted.
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| 5. |
- Lamxay, Vichith, et al.
(författare)
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Ethnobotany, Biodiversity and Malaria in Nakai-Nam Theun NBCA, Laos: Three PhD projects
- 2006
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Ingår i: Program of the Society for Economic Botany 47th Annual Meeting.
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Konferensbidrag (populärvet., debatt m.m.)abstract
- Starting January 2006 the Department of Biology, National University of Laos and the Department of Systematic Botany have started a collaboration funded to Sida-SAREC to train three Ph.D. students at Uppsala University. The projects evolve around ethnobotany, biodiversity studies, and malaria prevention in the inaccessible Nakai-Nam Theun National Biodiversity Conservation Area in the Annamite mountains bordering on Vietnam. The Nakai-Nam Theun NBCA was chosen for fieldwork, because the 2001 review of the Laos protected area system pointed out that the Nakai- Nam Theun National Biodiversity Conservation Area has the highest need for development, harbors the richest biodiversity, and would be the most effective area for improvement. Objectives The objectives are to study: 1a) The taxonomy of Amomum (Zingiberaceae) for the Flora of Cambodia, Laos, and Vietnam; 1b) The feasibility of micropropagation of Amomum to create a cash-crop alternative to wild crafting; 2a) The biodiversity of ethnobotanically used plants in the area; 2b) The spread of ethnobotanical knowledge between ethnic groups and mountain valleys; 3a) The incidence of malaria, and the traditional knowledge about natural mosquito repellents; 3b) The effectiveness of impregnating mosquito nets with natural or chemical repellants. Methods Study objectives 1a and 2a require extensive collection of herbarium vouchers. Objective 1b will be studied using micropropagation techniques through Khon Kaen University, Thailand. Objectives 2a and 3a will be studied using semi-structured interviews and forest walks. 3a will be done with the help of doctors from the Faculty of Medicine, NUOL, and 2b and 3b will be analyzed using various statistical methods. Results During the first three months of this project a preliminary study of the genus Amomum has been finished, and a few hundred herbarium vouchers have been collected in the NBCA, of which at least one is a new species to science. Conclusion This collaboration will hopefully initiate a lasting and ongoing tradition of ethnobotanical research in Laos. It will result in a better understanding of the value of plants in the livelihoods of the peoples in the Nakai-Nam Theun NBCA, and will hopefully improve their situation through knowledge on efficacy of traditionally used plants, introduction of clonal Amomum varieties, and introducing mosquito nets and a sustainable impregnation system based on naturally available plants. In addition it will result in the training of three Ph.Ds., a number of scientific publications, and probably a lot more.
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| 6. |
- Vongsombath, Chanda, 1961-
(författare)
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Botanical Repellents and Pesticides Traditionally Used Against Haematophagous Invertebrates in Lao PDR
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Haematophagous parasites and disease vectors such as leeches, ticks, mites, lice, bed bugs, mosquitoes, and myiasis-causing fly larvae are common health problems in Lao Peoples Democratic Republic (Lao PDR). A main aim of my field work in Lao PDR in 2006-2010 was to document traditional knowledge among different ethnic groups about plants that people use to repel or to kill blood-feeding invertebrates. We carried out structured interviews in 66 villages comprising 17 ethnic groups, covering a range of ethnic group, throughout Lao PDR and recorded a total of 92 plant species - in 123 different plant-ectoparasite combinations - that are used as traditional repellents and/or as “pesticides” to kill "pest" invertebrates. Traditional use was confirmed in the scientific literature for 74 of these plant species, and for an additional 13 species based on literature on closely related species. We concluded that repellents and pesticides from many plant species are commonly used in the Lao countryside. We also investigated traditionally used Lao plants for their activity to repel or to kill certain disease vectors and parasites. Target organisms were mosquitoes (Diptera, Culicidae), fly larvae (Diptera, Cyclorrhapha) in fermented fish production, and terrestrial blood-sucking leeches (Hirudinea, Haemadipsidae). The potential mosquito repellent activities of essential oils of Croton roxburghii (Euphorbiaceae), Hyptis suaveolens (Lamiaceae), and Litsea cubeba (Lauraceae) were evaluated in the field near Vientiane. Oils at concentrations of 1.7-6.7 µg/cm2 were significantly repellent to Aedes, Armigeres and Culex attracted to human baits. The activities against fly larvae, infesting fermenting fish, of three plant species, Tadehagi triquetrum (Fabaceae), Uraria crinita (Fabaceae) and Bambusa multiplex (Poaceae) were investigated: When fresh material of the plants was added on top of fermenting fish infested with fly larvae significant proportions of the larvae were repelled or killed. The total protective effect, i.e., repellent and killing effect combined, of T. triquetrum, U. crinita, and B. multiplex was 60-83 %, 77-90 %, and 60-93 %, respectively. Field evaluation of the potential leech repellent activities of water extracts of Sapindus rarak (Sapindaceae), Catunaregam spathulifolia (Rubiaceae) and Vernonia elaeagnifolia, (Asteraceae) impregnated on stockings and worn by persons in two leech-infested biotopes revealed leech repellent activities of 82.6%, 62.6% and 63.0%, respectively. The corresponding repellencies of deltamethrin and diethyl-3-methyl-benzamide (DEET) were 73.1% and 88.4%, respectively. Identification of the active components in certain of the plants with the ultimate aim to develop more optimal, less costly repellents, insecticides, acaricides, and anti-leech compounds as alternatives to synthetic repellents and pesticides against blood-feeding insects, ticks, mites, and leeches is in progress.
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| 7. |
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| 8. |
- Vongsombath, Chanda, et al.
(författare)
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Keeping leeches at bay : Field evaluation of plant-derived extracts against terrestrial blood-sucking leeches (Haemadipsidae) in Lao PDR
- 2011
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Ingår i: Acta Tropica. - : Elsevier BV. - 0001-706X .- 1873-6254. ; 119:2-3, s. 178-182
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Tidskriftsartikel (refereegranskat)abstract
- Terrestrial blood-sucking leeches (Haemadipsidae) are common in the damp forests of the subtropical and tropical Indo-Pacific region. Members of the genus Haemadipsa are abundant in Laos and adjacent countries of Southeast Asia, and discomfort to people and livestock. Plant-derived repellents against arthropods and leeches are common in Lao PDR, and have been used by Lao ethnic groups for generations. Numerous studies have been conducted on the efficacy of traditional plant-derived repellents against mosquitoes but only a few on repellents against terrestrial blood-sucking leeches. Field experiments were conducted to evaluate the leech repellent activities of aqueous extracts of three traditionally used plant species, Sapindus rarak DC., Catunaregam spathulifolia Tirv. and Vernonia elaeagnifolia DC. Stockings impregnated with aqueous extracts exhibited moderate to high leech repellent activity, C spathulifolia (62.6%), V. elaeagmfolia (63.0%), and S. rarak (82.6%). The corresponding repellencies of deltamethrin and DEET were 73.1% and 88.4%, respectively. An aqueous extract of S. rarak applied on cloth at a concentration of 1.9 mg/cm(2) is an effective and practical prevention method significantly reducing the number of blood-feeding leeches recorded on stockings worn by humans. This plant species is common in Southeast Asia and can be obtained at limited or no cost.
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