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A Fly in the Ointment: Evaluation of Traditional Use of Plants to Repel and Kill Blowfly Larvae in Fermented Fish
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology.
2011 (English)In: PLoS ONE, ISSN 1932-6203, Vol. 6, no 12, e29521Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
2011. Vol. 6, no 12, e29521
National Category
Agricultural Sciences Botany
Identifiers
URN: urn:nbn:se:uu:diva-149968DOI: 10.1371/journal.pone.0029521ISI: 000298665600041OAI: oai:DiVA.org:uu-149968DiVA: diva2:406104
Available from: 2011-03-24 Created: 2011-03-24 Last updated: 2015-08-11Bibliographically approved
In thesis
1. Botanical Repellents and Pesticides Traditionally Used Against Haematophagous Invertebrates in Lao PDR
Open this publication in new window or tab >>Botanical Repellents and Pesticides Traditionally Used Against Haematophagous Invertebrates in Lao PDR
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2011. 49 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 825
Keyword
Ethnobotany, fly larvae, Lao PDR, medical entomology, mosquito repellents, myiasis, plant-based insecticides, terrestrial leeches, Haemadipsidae
National Category
Biological Systematics Microbiology
Research subject
Biology with specialization in Systematics
Identifiers
urn:nbn:se:uu:diva-149991 (URN)978-91-554-8075-2 (ISBN)
Public defence
2011-05-19, Zootissalen, Evolutionsmuseet (Museum of Evolution), Villavägen 9, Uppsala, 14:00 (English)
Opponent
Supervisors
Available from: 2011-04-21 Created: 2011-03-24 Last updated: 2011-05-05
2. Snake Gourds, Parasites and Mother Roasting: Medicinal plants, plant repellents, and Trichosanthes (Cucurbitaceae) in Lao PDR
Open this publication in new window or tab >>Snake Gourds, Parasites and Mother Roasting: Medicinal plants, plant repellents, and Trichosanthes (Cucurbitaceae) in Lao PDR
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background. Traditional plant use was studied in Lao PDR. Research focused on medicinal plant use by the Brou, Saek and Kry ethnic groups, traditional plant repellents against parasitic arthropods and leeches, and the phylogeny and biogeography of the medicinally-important snake gourd genus (Trichosanthes, Cucurbitaceae).  Methods. The ethnobiology research used a combination of structured interviews, village surveys, botanical collecting, hydro-distillation, GC-MS analysis, literature studies, and laboratory experiments. The plant systematics research used a combination of morphological studies, molecular biology laboratory work, and phylogenetic, dating and biogeographical analysis.  Results. Informants reported the use of close to 100 species to repel arthropods and leeches, many of which have constituents with documented efficacy.  Brou, Saek and Kry informants use over 75 plant species for women’s healthcare, mainly during the postpartum period for steam sauna, steam bath, hotbed, mother roasting, medicinal decoctions and infusions, and postpartum diet.  A molecular phylogeny of Trichosanthes and Gymnopetalum using a broad sampling of ~60% of their species and 4756 nucleotides of nuclear and plastid DNA shows that Gymnopetalum is nested within Trichosanthes. Fossil-calibrated Bayesian molecular dating of the Trichosanthes phylogeny reveals an early Oligocene origin of the genus, and many of the extant sections originating and diversifying during the Miocene. Biogeographical analysis shows a likely East or South Asian origin of Trichosanthes, with lineages diversifying and spreading throughout Australasia from the early Pliocene to the Pleistocene.  Discussion. Traditional plant use in Lao PDR is common and widespread. The presence among the repellent species of economical alternatives to costly synthetic repellents is tenable, and the subject of ongoing studies.  Postpartum traditions and medicinal plant use are essential parts of childbirth and postpartum recovery in these ethnic groups, and many other groups in Lao PDR. Efforts to improve maternal healthcare and reduce maternal and infant mortality need to integrate these traditions with modern notions of healthcare to achieve wider adoption. Documenting all possible uses of commonly used medicinal plant species shows that similarity in use between these ethnic groups is relatively low considering that they share, and have shared for many generations, the same environment and resources. A lack of effective cures leads to a process of continuous innovation, where effective cures are shared between cultures, but remedies of only cultural importance, or those under evaluation are culture-specific.  The Trichosanthes phylogeny implies the merging of Gymnopetalum into Trichosanthes, and this is done using available names or new combinations. A synopsis of Trichosanthes, the new combinations, and a revision of the species in Australia, are made and presented.  Conclusions. Traditional plant use is widespread in Lao PDR, and of significance to many people as a source of primary healthcare and inexpensive repellents. The important medicinal plant genus Trichosanthes includes Gymnopetalum, and has a complex biogeographic history with multiple colonization events of Australasia.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 59 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 901
Keyword
Trichosanthes, Ethnobotany, Similarity of Knowledge, Biogeography, Molecular Dating, Brou, Saek, Kry, Mother roasting, Postpartum healthcare, Parturition, Childbirth, Traditional Medicine, Plant repellents, Fermented fish
National Category
Biological Sciences
Research subject
Biology with specialization in Systematics
Identifiers
urn:nbn:se:uu:diva-168536 (URN)978-91-554-8281-7 (ISBN)
Public defence
2012-03-30, Lindahlsalen, Norbyvägen 18, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2012-03-02 Created: 2012-02-13 Last updated: 2012-03-29Bibliographically approved

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