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Plants as Sources of Natural and Effective Acaricides: Against Ixodes ricinus  (Acari: Ixodidae)
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology. uppsala university.ORCID iD: 0000-0001-9341-2052
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Ticks and tick-borne diseases are major health hazards worldwide, with increasing numbers of cases of Lyme disease and tick-borne encephalitis reported yearly. Meanwhile, concerns about the environmental impact and safety of chemical acaricides are driving research into alternative control methods, such as plant-based acaricides. I evaluated eight plant species for their toxicity and repellency against nymphs of Ixodes ricinus (Acari: Ixodidae), the most important life cycle stage of tick-borne infection of humans.

Paper I examines the toxicity of the principal active component of the essential oil (EO) of lemon eucalyptus (Corymbia citriodora), p-menthane-3,8-diol (PMD). At 4 h of exposure time (ET), lethal PMD concentrations for 50% mortality (LC50) were 0.035–0.037 mg/cm² and for 95% mortality (LC95) were 0.095-0.097 mg/cm². For 0.1 mg/cm², lethal times for 50% mortality (LT50) were 2.1-2.8 h and for 95% mortality (LT95) were 3.9-4.2 h. An open filter assay gave the most consistent results of five methods tried. Paper II investigated the toxicity of ylang-ylang oil (YYO) and star anise oil (SAO), two naturally occurring, commercially available and inexpensive EOs. Oils were tested at 0.05, 0.1, 0.2, and 0.4μl/cm², and dead nymphs counted at 30-min intervals up to 5h and then at 24, 48 and 72h. For YYO, an exposure of 4.4h resulted in LC95 for 0.4 μl/cm² and LC50 for 0.2μl/cm². The LT95 was 3h for 0.4 μl YYO/cm² and 4.3 h for 0.2 μl/cm². For SAO, the highest concentration (0.4 μl/cm²) only reached LC50 at 14 h and LT95 was 24h. Thus, YYO is a much stronger acaricide but SAO still showed significant toxicity.

Paper III investigated two plants of traditional medicinal or economic importance in Libya -Salvadora persica, (Miswak) and Rosmarinus officinalis (Libyan Rosemary). EOs were extracted from wild-collected leaves by steam distillation. Oils were tested on I. ricinus nymphs and their chemical composition analysed by GC-MS. R. officinalis EO at 0.5 and 1µl/cm² exhibited 20% and 100% mortality, respectively, after about 5h of ET. The LC50 and LC95 for 1µl/cm² R. officinalis oil were 0.7 and 0.95 µl/cm², respectively. S. persica oil at 1µl/cm² gave 95% repellency up to 1.5h, reducing to 50% at around 5.45 h, but no significant mortality even after 24h ET. GC-MS analysis showed both oils to be rich in the monoterpenes 1,8 cineol, α-pinene and β-pinene with values of 20.8%, 5.9% and 16.8 %, respectively, for S. persica and 24.07%, 13.03% and 2.45%, respectively, for R. officinalis.

Paper IV investigated EOs extracted from leaves of three additional native Libyan plants - Artemisia herba alba (white wormwood), Origanum majorana (oregano) and Juniperus phoenicea (Ar-aar). At 1µl/cm², the LT95 for both A. herba and J. phoenicea EO was 2h versus 72 h for O. majorana oil. GC-MS analyses gave plant specific combinations of the monoterenoids α-pinene, 1,8-cineol, camphor, linalool, terpinene-4-ol, α-terpinol, β-caryophyllene and β-thujanone. EO of A.herba alba contained most of the oxygenated monoterpenes, which all are all known to have insecticidal activity.

Taken together, all the EOs used in this study show a broad spectrum of effects against I. ricinus nymphs, making them good candidates for controlling ticks and, thereby, the diseases they carry.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2019. , p. 62
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1797
Keywords [en]
Acaricidal, Ixodes ricinus, Libyan plants, essential oils, Plant-derived acaricides.
National Category
Biological Systematics
Research subject
Biology with specialization in Systematics
Identifiers
URN: urn:nbn:se:uu:diva-381142ISBN: 978-91-513-0629-2 (print)OAI: oai:DiVA.org:uu-381142DiVA, id: diva2:1302413
Public defence
2019-05-28, Lindahlsalen, Evolutionary Biology Center, Uppsala University, Norbyvägen 18D, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2019-05-02 Created: 2019-04-04 Last updated: 2019-06-17Bibliographically approved
List of papers
1. Acaricidal effects of Corymbia citriodora oil containing para-menthane-3,8-diol against nymphs of Ixodes ricinus (Acari: Ixodidae)
Open this publication in new window or tab >>Acaricidal effects of Corymbia citriodora oil containing para-menthane-3,8-diol against nymphs of Ixodes ricinus (Acari: Ixodidae)
2009 (English)In: Experimental & applied acarology, ISSN 0168-8162, E-ISSN 1572-9702, Vol. 48, no 3, p. 251-262Article in journal (Refereed) Published
Abstract [en]

The toxicity of para-menthane-3,8-diol (PMD), the main arthropod-repellent compound in the oil of the lemon eucalyptus, Corymbia citriodora, was evaluated against nymphs of Ixodes ricinus using five methods (A-E) of a contact toxicity bioassay. Mortality rates were estimated by recording numbers of dead nymphs at 30 min intervals during the first 5 h after the start of exposure and at longer intervals thereafter. The mortality rate increased with increasing concentration of PMD and duration of exposure with a distinct effect after 3.5 h. From the results obtained by methods A, C and E, the LC(50) range was 0.035-0.037 mg PMD/cm(2) and the LC(95) range was 0.095-0.097 mg PMD/cm(2) at 4 h of exposure; the LT(50) range was 2.1-2.8 h and the LT(95) range was 3.9-4.2 h at 0.1 mg PMD/cm(2). To determine the duration of toxic activity of PMD, different concentrations (0.002, 0.01, 0.1 mg PMD/cm(2)) were tested and mortality was recorded at each concentration after 1 h; thereafter new ticks were tested. This test revealed that the lethal activity of PMD remained for 24 h but appeared absent after 48 h. The overall results show that PMD is toxic to nymphs of I. ricinus and may be useful for tick control.

Keywords
Tick repellents, plant-based repellents, Ixodes ricinus, Corymbia citriodora, para-menthane-3, 8-diol, PMD, ticks, toxicity
National Category
Biological Sciences
Identifiers
urn:nbn:se:uu:diva-102712 (URN)10.1007/s10493-009-9236-4 (DOI)000266656900006 ()19169833 (PubMedID)
Available from: 2009-05-12 Created: 2009-05-11 Last updated: 2019-04-04Bibliographically approved
2. Acaricidal properties of ylang-ylang oil and star anise oil against nymphs of Ixodes ricinus (Acari: Ixodidae)
Open this publication in new window or tab >>Acaricidal properties of ylang-ylang oil and star anise oil against nymphs of Ixodes ricinus (Acari: Ixodidae)
2018 (English)In: Experimental & applied acarology, ISSN 0168-8162, E-ISSN 1572-9702, Vol. 76, no 2, p. 209-220Article in journal (Refereed) Published
Abstract [en]

Ylang-ylang oil (YYO) from Cananga odorata (Lam.) Hook.f. & Thomson and star anise oil (SAO) from Illicium verum Hook.f. were tested at four concentrations 0.05, 0.1, 0.2, 0.4 mu l/cm(2). Mortality rates were obtained by counting dead nymphs at 30-min intervals during the first 5h after the start of exposure and then at 24, 48 and 72h. Mortality increased with increasing oil concentration and time of exposure. The two highest concentrations of YYO (0.2, 0.4 mu l/cm(2)) gave maximum lethal concentrations (LC) of 50 and 95% mortality after 4.5h exposure. Mortality of 95% was obtained after 24h with the next highest dose (0.1 mu l/cm(2)), whereas LC95 required 3days with the lowest YYO (0.05 mu l/cm(2)). The lethal effect time (LT) was correlated with the duration of exposure, with a significant effect at 0.4l YYO/cm(2) after 3h' (LT50=3.2h, LT95=4.3h). In contrast, only the highest concentration of SAO, 0.4 mu l SAO/cm(2), showed increasing mortality with time of exposure. This reached LT50 after 10h and LT95 after 24h. However, with the lower concentration (0.2 mu l/cm(2)) 50% mortality was reached after 24h and 100% at 72h. At to the lowest concentration of SAO (0.1 mu l/cm(2)), 67% mortality after 48h. The study indicates that YYO and SAO exhibit strong acaricidal properties against nymphs of I. ricinus and suggest that both YYO and SAO should be evaluated as potentially useful in the control of ticks.

Place, publisher, year, edition, pages
SPRINGER, 2018
Keywords
Acaricide, Cananga odorata, Illicium verum, Ixodes ricinus
National Category
Pharmacology and Toxicology
Identifiers
urn:nbn:se:uu:diva-368454 (URN)10.1007/s10493-018-0299-y (DOI)000446985800005 ()30302625 (PubMedID)
Funder
Swedish Research Council FormasSida - Swedish International Development Cooperation Agency
Available from: 2018-12-05 Created: 2018-12-05 Last updated: 2019-04-04Bibliographically approved
3. The repellency and toxicity effects of Essential oils from the Libyan plants Salvadora persica and Rosmarinus officinalis against nymphs of Ixodes ricinus.
Open this publication in new window or tab >>The repellency and toxicity effects of Essential oils from the Libyan plants Salvadora persica and Rosmarinus officinalis against nymphs of Ixodes ricinus.
Show others...
2019 (English)In: Experimental & applied acarology, ISSN 0168-8162, E-ISSN 1572-9702, Vol. 77, no 4, p. 585-599Article in journal (Refereed) Published
Abstract [en]

Essential oils extracted from the leaves of Libyan Rosemary (Rosmarinus officinalis L.), and Miswak (Salvadora persica L.) were evaluated for their acaricidal and repellent effects on Ixodes ricinus L. nymphs (Acari: Ixodidae) using a bioassay based on an “open filter paper method".  R. officinalis leaf essential oil diluted to 0.5 and 1µl/cm ² in acetone exhibited, respectively, 20% and 100% tick mortality after about 5 hours of exposure. A total of 50% and 95% of I. ricinus nymphs were killed by direct contact with the oil when exposed to lethal concentrations (LC) of 0.7µl/cm² (LC50) and 0.95 µl/cm² (LC95), respectively. The LC50 (0.5µl/cm²) was reached before the end of the first 24 hours of exposure time (ET), as tick mortality at 24 hours was 60%. S. persica leaf essential oil at 1µl/cm² showed a significant repellency effect against I. ricinus nymphs at 1.5 hours ET. A 95% repellency was observed at a repellent concentration (RC95) of 1µl/cm² of S. persica, but no significant mortality was recorded at this dose of S. persica oil. Gas chromatography-mass spectrometry analyses showed that the main monoterpenes in both oils were 1,8-cineol, α-pinene, and β-pinene, although in markedly different proportions. These results suggest that essential oils have substantial potential as alternative approaches for I. ricinus tick control.

Keywords
Rosmarinus officinalis, Salvadora persica, essential oils, acaricidal, Ixodes ricinus.
National Category
Zoology
Research subject
Biology with specialization in Systematics
Identifiers
urn:nbn:se:uu:diva-381130 (URN)10.1007/s10493-019-00373-5 (DOI)000468592300010 ()31089978 (PubMedID)
Available from: 2019-04-04 Created: 2019-04-04 Last updated: 2019-08-28Bibliographically approved
4. Toxicity against Ixodes ricinus nymphs of essential oils from the Libyan plants Artemisia herba alba, Origanum majorana and Juniperus phoenicea
Open this publication in new window or tab >>Toxicity against Ixodes ricinus nymphs of essential oils from the Libyan plants Artemisia herba alba, Origanum majorana and Juniperus phoenicea
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

ABSTRACT Ixodes ricinus (L.) (Acari: Ixodidae) is a major vector for the transmission of several important human pathogens. The aim of the study was to evaluate the in vitro efficacy of different concentrations of essential oils (Eos) on I. ricinus tick nymphs. Oils were obtained from the leaves of three plants native to Libya: white wormwood (Artemisia herba alba Asso), marjoram (Origanum majorana L.) and Arâr (Juniperus phoenicea L., English common name Phoenician juniper). Assays were done using the “open filter paper method". Two concentrations from each oil, 0.5 and 1µl/cm, were tested. And the toxic effect was measured in terms of the lethal concentrations (LC50, LC95) and lethal time (LT50, LT95). Mortality rates were obtained by counting the surviving nymphs every 30 minutes for the first five hours and then at 24, 48 and 72 h. A mortality of 100% was recorded at the higher concentration of oils (1µl/cm²) from A. herba alba and J. phoenicea at the first 2 hours of exposure. With O. majorana 100% mortality was only reached on the third day (72h), and this effect decreased noticeably with 0.5µl/cm² oil at the same exposure time. However, 50% of ticks showed a paralysis effect and less movement after 2 hours. Whereas the LC50 of mortality was reached within the first 24h of ET at 0.5µl/cm² of O. majorana, which produced 60% tick’s mortality. Chemical composition of the essential oils was elucidated by gas chromatography-mass spectrometry analyses. These results suggest that essential oils merit further investigation as components of alternative approaches for I. ricinus tick control.

 

Keywords
Libyan plants, Artemisia herba alba, Origanum majorana, Juniperus phoenicea, Acaricidal, Ixodes ricinus.
National Category
Zoology
Research subject
Biology with specialization in Systematics
Identifiers
urn:nbn:se:uu:diva-381133 (URN)
Available from: 2019-04-04 Created: 2019-04-04 Last updated: 2019-04-12

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