| 1. |
- Pålsson, Katinka, et al.
(författare)
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Tick repellent substances in the essential oil of Tanacetum vulgare
- 2008
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Ingår i: Journal of medical entomology. - 0022-2585 .- 1938-2928. ; 45:1, s. 88-93
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Tidskriftsartikel (refereegranskat)abstract
- The repellent effect of the essential oils of flower heads of the aromatic plant tansy, Tanacetum vulgare L. (Asteraceae), originating from Sweden, was tested against host-seeking nymphs of the common tick Ixodes ricinus (L.). The essential oils were obtained by steam distillation (SD) and by using an online solvent extraction separation setup. Further fractionations of the SD oils were obtained by medium-pressure liquid chromatography on silica gel. The volatiles of the essential oils and the fractions that exhibited strong tick repellency (90-100%) were collected by solid phase microextraction and identified by gas chromatography-mass spectrometry. The chemical analyses of the oils show that the populations of T. vulgare from Uppsala and Stockholm may represent different chemotypes, but that they exhibited similar tick repellency. Main volatiles detected from oils of T vulgare collected at Uppsala were a-pinene (27%), beta-pinene (11%), pinocamphone (11%), 1,3,3-trimethylcyclohex-l-ene-4-carboxaldehyde (11%), and 1,8-cineole (10%). In the sample collected in Stockholm, the main components were beta-thujone (39%) and camphor (23%) followed by a-thujone (11%) and 1,8-cineole (8%). When constituents in the oils, e.g., alpha-terpineol, 4-terpineol, alpha + beta-thujone, 1,8-cineol, verbenol, and verbenone, were tested separately (each diluted 0.5%, vol:vol), 64-72% tick repellency was obtained.
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| 2. |
- Garboui, Samira, et al.
(författare)
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Tick repellent properties of three Libyan plants
- 2009
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Ingår i: Journal of medical entomology. - : Oxford University Press (OUP). - 0022-2585 .- 1938-2928. ; 46:6, s. 1415-1419
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Tidskriftsartikel (refereegranskat)abstract
- Specimens of Salvadora persica Wallich (Salvadoraceae), Pistacia atlantica Desfontaines (Anacardiaceae), and Juniperus phoenicea L. (Cupressaceae) were collected at The Green Mountain in northeastern Libya. The tick-repellent effects of the essential oils from the plants were evaluated using host-seeking nymphs of Ixodes ricinus L. (Acari: Ixodidae) in the laboratory. Significant tick repellent effects were observed for the oils of all three species, but the duration of action was short. The oils were obtained by steam distillation. Volatile compounds of the essential oils were collected by solid phase microextraction and the constituents were identified by gas chromatography-mass spectrometry.
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| 3. |
- Jaenson, T. G. T., et al.
(författare)
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Evaluation of extracts and oils of mosquito (Diptera : Culicidae) repellent plants from Sweden and Guinea-Bissau
- 2006
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Ingår i: Journal of medical entomology. - : Oxford University Press (OUP). - 0022-2585 .- 1938-2928. ; 43:1, s. 113-119
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Tidskriftsartikel (refereegranskat)abstract
- In laboratory tests, ethyl acetate extracts of Hyptis, suaveolens Poit. from Guinea-Bissau and Rhododendon tomentosum (Stokes) H. Harmaja (formerly Ledum palustre L.) and Myrica gale L. significantly reduced probing activity of Aedes aegypti (L.). In the field in southern Sweden, extracts of leaves of R. tomentosum, M. gale, and Achillea millefolium L. significantly reduced biting by Aedes mosquitoes. Volatile compounds from M. gale, R. tomentosum, A. millefolium, and H. suaveolens were collected by solid phase microextraction (SPME). Alternatively, compounds in the plants were subjected to extraction by organic solvents of different polarities or by steam distillation and collection by SPME. Compounds collected were identified by gas chromatography-mass spectrometry. Leaves of H. suaveolens contained mainly beta-caryophyllene, bergamotene, and terpinolene. The volatile fraction of an ethyl acetate extract of H. suaveolens was collected by SPME and included beta-caryophyllene, (-) -sabinene, beta-pinene, limonene, alpha-pinene, and bergamotene. The main volatiles detected were alpha-pinene, alpha-phellandrene, myrcene, and limonene from M. gale leaves or inflorescences; pcymene, sabinene, and terpinyl acetate from leaves of R. tornentoston; and (-)-germacrene D, beta-pinene, sabinene, and alpha-pinene from A. millefolium leaves or inflorescences. The selected plant species contained numerous volatiles known to have insecticidal, acaricidal, pesticidal, and/orinsect repellent properties.
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| 4. |
- Lindh, Jenny, et al.
(författare)
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Oviposition Responses of Anopheles gambiae s.s. (Diptera Culicidae) and Identification of Volatiles from Bacteria-Containing Solutions :
- 2008
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Ingår i: Journal of medical entomology. - : Oxford University Press (OUP). - 0022-2585 .- 1938-2928. ; 45:6, s. 1039-1049
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a dual-choice oviposition bioassay was used to screen responses of gravid An. gambiae toward 17 bacterial species, previously isolated from Anopheles gambiae s.l. (Diptera: Culicidae) midguts or oviposition sites. The 10 isolates from oviposition sites have been identified by phylogenetic analyses of their 16S rRNA genes. Eight of the 10 isolates were gram-positive, out of which six belonged to the Bacilli class. Solid phase microextraction and gas chromatography coupled to mass spectrometry (GC-MS) were used to identify the volatiles emitted From the bacterial isolates, Aromatic and aliphatic alcohols, aliphatic ketones, alkylpyrazines, dimethyl oligosulfides, and indole were among the chemical compounds identified from the headspace above bacteria-containing saline. The mosquitoes laid significantly more eggs in six of the bacteria-containing solutions compared with the sterile solution. These six bacteria did not emit any compounds in common that could explain the positive oviposition response. Instead. the bacteria were grouped according to principal component analysis (PCA) based on the relative amouts of volatile emitted. The PCA-plots facilitated the identification of 13 putative oviposition attractants for An. gambiae mosquitoes.
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| 5. |
- Oliveira, E., et al.
(författare)
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High Levels of Hybridization between Molecular Forms of Anopheles gambiae from Guinea Bissau
- 2008
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Ingår i: Journal of medical entomology. - 0022-2585 .- 1938-2928. ; 45:6, s. 1057-1063
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Tidskriftsartikel (refereegranskat)abstract
- In the malaria vector Anopheles gambiae Giles sensu stricto, two molecular forms denoted M and S are considered units of incipient speciation within this species. Very low hybrid frequencies and significant genetic differentiation have been found in sympatric M- and S-form populations, We studied the molecular form composition and the degree of genetic differentiation at 15 microsatellites in two samples of An. gambiae collected ill two consecutive years from Bissau, Guinea Bissau. High frequencies of M/S hybrids (19-24%) were found in this area. Coincidently, very low levels of genetic differentiation were detected between forms when analysis involved microsatellites mapped at chromosome-3 (mean F-st 0.000-0.002). The single exception was the X-linked AGXH678, for which high differentiation was measured (F-st 0.158-0.301). This locus maps near the centromere of chromosome X, a low recombination region in which selection is likely to promote divergence between M and S forms. These results strongly suggest that the degree of isolation between M and S forms, considered the units of incipient speciation within An. gambiae, is not homogenous throughout the species distribution range.
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| 6. |
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