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Unelius, C. Rikard, ProfessorORCID iD iconorcid.org/0000-0001-7158-6393
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Publications (10 of 83) Show all publications
Zhao, T., Ganji, S., Bohman, B., Weinstein, P., Krokene, P., Borg-Karlsson, A.-K. & Unelius, C. R. (2019). Convergent evolution of semiochemicals across Kingdoms: bark beetles and their fungal symbionts. The ISME Journal, 13(6), 5-1545
Open this publication in new window or tab >>Convergent evolution of semiochemicals across Kingdoms: bark beetles and their fungal symbionts
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2019 (English)In: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 13, no 6, p. 5-1545Article in journal (Refereed) Published
Abstract [en]

Convergent evolution of semiochemical use in organisms from different Kingdoms is a rarely described phenomenon. Treekilling bark beetles vector numerous symbiotic blue-stain fungi that help the beetles colonize healthy trees. Here we show for the first time that some of these fungi are able to biosynthesize bicyclic ketals that are pheromones and other semiochemicals of bark beetles. Volatile emissions of five common bark beetle symbionts were investigated by gas chromatography-mass spectrometry. When grown on fresh Norway spruce bark the fungi emitted three well-known bark beetle aggregation pheromones and semiochemicals (exo-brevicomin, endo-brevicomin and trans-conophthorin) and two structurally related semiochemical candidates (exo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane and endo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1] nonane) that elicited electroantennogram responses in the spruce bark beetle Ips typographus. When grown on malt agar with 13C D-Glucose, the fungus Grosmannia europhioides incorporated 13C into exo-brevicomin and trans-conophthorin. The enantiomeric compositions of the fungus-produced ketals closely matched those previously reported from bark beetles. The production of structurally complex bark beetle pheromones by symbiotic fungi indicates cross-kingdom convergent evolution of signal use in this system. This signaling is susceptible to disruption, providing potential new targets for pest control in conifer forests and plantations.

Place, publisher, year, edition, pages
Nature Publishing Group, 2019
National Category
Chemical Sciences Ecology
Research subject
Natural Science, Ecological chemistry
Identifiers
urn:nbn:se:lnu:diva-71867 (URN)10.1038/s41396-019-0370-7 (DOI)000468529400012 ()30770902 (PubMedID)
Available from: 2018-03-27 Created: 2018-03-27 Last updated: 2019-06-12Bibliographically approved
Schiebe, C., Unelius, C. R., Ganji, S., Binyameen, M., Birgersson, G. & Schlyter, F. (2019). Styrene, (+)-trans-(1R,4S,5S)-4-Thujanol and Oxygenated Monoterpenes Related to Host Stress Elicit Strong Electrophysiological Responses in the Bark Beetle Ips typographus. Journal of Chemical Ecology, 45(5-6), 474-489
Open this publication in new window or tab >>Styrene, (+)-trans-(1R,4S,5S)-4-Thujanol and Oxygenated Monoterpenes Related to Host Stress Elicit Strong Electrophysiological Responses in the Bark Beetle Ips typographus
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2019 (English)In: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 45, no 5-6, p. 474-489Article in journal (Refereed) Published
Abstract [en]

Bark beetles kill apparently vigorous conifers during epidemics by means of pheromone-mediated aggregation. During non-endemic conditions the beetles are limited to use trees with poor defense, like wind-thrown. To find olfactory cues that help beetles to distinguish between trees with strong or weak defense, we collected volatiles from the bark surface of healthy felled or standing Picea abies trees. Furthermore, living trees were treated with methyl jasmonate in order to induce defense responses. Volatiles were analyzed by combined gas chromatography and electroantennographic detection (GC-EAD) on Ips typographus antennae. Compounds eliciting antennal responses were characterized by single sensillum recording for identification of specific olfactory sensory neurons (OSN). Release of monoterpene hydrocarbons decreased, while oxygenated compounds increased, from spring to early summer in felled trees. In both beetle sexes particular strong EAD activity was elicited by trace amounts of terpene alcohols and ketones. 4-Thujanol gave a very strong response and the absolute configuration of the tested natural product was assigned to be (+)-trans-(1R,4S,5S)-thujanol by stereoselective synthesis and enantioselective gas chromatography. One type of OSN responded to all ketones and five other OSN were characterized by the type of compounds that elicited responses. Three new OSN classes were found. Of the eight EAD-active compounds found in methyl jasmonate-treated bark, the known anti-attractant 1,8-cineole was the one most strongly induced. Our data support the hypothesis that highly active oxygenated host volatiles could serve as positive or negative cues for host selection in I. typographus and in other bark beetles.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Oxygenated monoterpenes, Styrene, 4-thujanol, GC-EAD, Single-sensillum recordings, SSR, Host chemistry, Plant defense
National Category
Chemical Sciences Ecology
Research subject
Natural Science, Ecological chemistry
Identifiers
urn:nbn:se:lnu:diva-86888 (URN)10.1007/s10886-019-01070-8 (DOI)000471639800006 ()31053976 (PubMedID)
Available from: 2019-07-18 Created: 2019-07-18 Last updated: 2019-07-18Bibliographically approved
Bohman, B., Weinstein, A. M., Unelius, C. R. & Lorenzo, M. G. (2018). Attraction of Rhodnius prolixus males to a synthetic female-pheromone blend. Parasites & Vectors, 11, Article ID 418.
Open this publication in new window or tab >>Attraction of Rhodnius prolixus males to a synthetic female-pheromone blend
2018 (English)In: Parasites & Vectors, ISSN 1756-3305, E-ISSN 1756-3305, Vol. 11, article id 418Article in journal (Refereed) Published
Abstract [en]

Background: The triatomine bug Rhodnius prolixus Stal, 1859 (Heteroptera: Reduviidae) is the primary vector of Chagas disease in Colombia and Venezuela. An important step in controlling Chagas disease is monitoring the growth and spread of bug populations to inform effective management. Such monitoring could be carried out using pheromone traps. To develop effective pheromone traps, it is vital to understand the pheromone chemistry of R. prolixus. Previous studies have found that female R. prolixus metasternal gland secretions induce males to: leave shelters, take off, orientate during walking, aggregate around mating pairs, and mate. This study aims to identify a synthetic blend of female metasternal gland compounds that could be used to attract R. prolixus. Results: We investigated the electrophysiological activity of the ten most abundant compounds in female R. prolixus metasternal glands using single sensillum recordings. In total we obtained 60 recordings from basiconic sensilla in male R. prolixus. In 31 of these recordings, responses to individual compounds were observed. Each of the ten tested compounds elicited neuron responses in a minimum of eight recordings. Having confirmed their electrophysiological activity, we tested these ten compounds by presenting them to male Rhodnius prolixus in a 7 olfactometer. Male bugs showed a significant preference for the blend of metasternal gland compounds compared to the clean air control. Conclusions: A simple blend of ten compounds found in female R. prolixus metasternal glands is attractive to conspecific males. All compounds in the blend are either commercially available at low cost, or easily synthetically prepared from simple precursors. We hope that this blend will be evaluated as a lure for pheromone traps in field bioassays.

Place, publisher, year, edition, pages
BioMed Central, 2018
Keywords
Rhodnius prolixus, Chagas disease, SSR, Olfactometer, Pheromone, Metasternal gland, Trap, Volatiles
National Category
Biological Sciences Chemical Sciences
Research subject
Natural Science, Ecological chemistry
Identifiers
urn:nbn:se:lnu:diva-77398 (URN)10.1186/s13071-018-2997-z (DOI)000438713100001 ()30012183 (PubMedID)
Available from: 2018-08-29 Created: 2018-08-29 Last updated: 2019-05-20Bibliographically approved
Unelius, C. R., Bohman, B. & Nordlander, G. (2018). Comparison of Phenylacetates with Benzoates and Phenylpropanoates as Antifeedants for the Pine Weevil, Hylobius abietis. Journal of Agricultural and Food Chemistry, 66(44), 11797-11805
Open this publication in new window or tab >>Comparison of Phenylacetates with Benzoates and Phenylpropanoates as Antifeedants for the Pine Weevil, Hylobius abietis
2018 (English)In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 66, no 44, p. 11797-11805Article in journal (Refereed) Published
Abstract [en]

This study concludes an extensive investigation of antifeedants for the pine weevil, Hylobius abietis (Coleoptera: Curculionidae), an economically important pest of planted conifer seedlings. Building on the previously reported antifeedant effects of benzoates and phenylpropanoids (aromatic compounds with one- or three-carbon-atom substituents on the benzene ring), we here report the antifeedant effects of compounds with two-carbon-atom side chains (i.e., phenylacetates). We also present new results; the best antifeedants from the benzoate class were tested at 10-fold lower concentrations in order to find the optimal antifeedants. Generally, for all three compound classes, efficient antifeedants were found to have one or two methyl, chloro, or methoxy substituents on the aromatic ring. For monosubstituted phenylpropanoids, the substituent preferably should be in the para-position. In the search for synergistic antifeedant effects among the three compound classes, combinations of compounds from the three classes were tested in binary and ternary mixtures.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
pine weevil, Hylobius abietis, synergism, conifer-seedling protection, feeding deterrent, structure activity relationships
National Category
Ecology Chemical Sciences
Research subject
Natural Science, Ecological chemistry
Identifiers
urn:nbn:se:lnu:diva-79004 (URN)10.1021/acs.jafc.8b03830 (DOI)000449888000029 ()30350979 (PubMedID)
Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2018-12-06Bibliographically approved
El-Sayed, A. M., Unelius, C. R. & Suckling, D. M. (2018). Honey Norisoprenoids Attract Bumble Bee, Bombus terrestris, in New Zealand Mountain Beech Forests. Journal of Agricultural and Food Chemistry, 66(50), 13065-13072
Open this publication in new window or tab >>Honey Norisoprenoids Attract Bumble Bee, Bombus terrestris, in New Zealand Mountain Beech Forests
2018 (English)In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 66, no 50, p. 13065-13072Article in journal (Refereed) Published
Abstract [en]

Three varieties of honey of different dominant floral origin were found to attract social Hymenoptera, including the large earth bumble bee, Bombus terrestris, in a New Zealand mountain beech forest. This study was undertaken to identify volatile organic compounds that induce the attraction of bumble bees to honeybee (Apis mellifera) honey. We analyzed the chemical composition of the volatile organic compounds produced in three distinct varieties of honey (i.e., manuka, honeydew, and clover honey). The composition of the chemical profile of the three honey varieties differed in the quality and in the ratio of compounds in the headspace. o-Methoxyacetophenone was the main compound in the headspace of all three honey varieties. Among the 40 compounds identified in the headspace in the three varieties, only seven shared compounds (i.e., benzaldehyde, benzyl alcohol, phenylacetaldehyde, 2-phenylethanol, isophorone, 4-oxoisophorone, and o-methoxyacetophenone) were present in the headspace of the three honey varieties. The relative attractiveness of various blends of the seven common compounds found in the three honey varieties was tested for the attraction to bumble bees in a mountain beech forest. A binary blend of isophorone and 4-oxoisophorone at a ratio of 90:10 was the most attractive blend for both bumble bee workers and queens. A small number of honey bee workers were also attracted to the former binary blend. Our study represents the first identification of a honey-derived attractant for bumble bees and honey bees. The potential application of our finding for monitoring of bumble bees or to enhance crop pollination and help to tackle the current concern of a global pollination crisis is discussed.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
social hymenoptera, bumble bees, honey, attractant, isophorone, 3, 5, 5-trimethylcyclohex-2-enone, 4-oxoisophorone, o-methoxyacetophenone
National Category
Organic Chemistry Ecology
Research subject
Natural Science, Ecological chemistry
Identifiers
urn:nbn:se:lnu:diva-79744 (URN)10.1021/acs.jafc.8b04175 (DOI)000454382400003 ()30415534 (PubMedID)
Available from: 2019-01-24 Created: 2019-01-24 Last updated: 2019-01-24Bibliographically approved
Franco, T. A., Xu, P., Brito, N. F., Oliveira, D. S., Wen, X., Moreira, M. F., . . . Melo, A. C. A. (2018). Reverse chemical ecology-based approach leading to the accidental discovery of repellents for Rhodnius prolixus, a vector of Chagas diseases refractory to DEET. Insect Biochemistry and Molecular Biology, 103, 46-52
Open this publication in new window or tab >>Reverse chemical ecology-based approach leading to the accidental discovery of repellents for Rhodnius prolixus, a vector of Chagas diseases refractory to DEET
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2018 (English)In: Insect Biochemistry and Molecular Biology, ISSN 0965-1748, E-ISSN 1879-0240, Vol. 103, p. 46-52Article in journal (Refereed) Published
Abstract [en]

Rhodnius prolixus is one of the most important vectors of Chagas disease in Central and South America for which repellents and attractants are sorely needed. Repellents like DEET, picaridin, and IR3535 are widely used as the first line of defense against mosquitoes and other vectors, but they are ineffective against R. prolixus. Our initial goal was to identify in R. prolixus genome odorant receptors sensitive to putative sex pheromones. We compared gene expression of 21 ORs in the R. prolixus genome, identified 4 ORs enriched in male (compared with female) antennae. Attempts to de-orphanize these ORs using the Xenopus oocyte recording system showed that none of them responded to putative sex pheromone constituents. One of the them, RproOR80, was sensitive to 4 compounds in our panel of 109 odorants, namely, 2-heptanone, gamma-octalactone, acetophenone, and 4-methylcychohexanol. Interestingly, these compounds, particularly 4-methylcyclohexanol, showed strong repellency activity as indicated not only by a significant decrease in residence time close to a host, but also by a remarkable reduction in blood intake. 4-Methylcyclohexanol-elicited repellency activity was abolished in RNAi-treated insects. In summary, our search for pheromone receptors led to the discovery of repellents for R. prolixus.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Odorant receptor, Rhodnius prolixus, Repellent, RNAi, DEET, Acetophenone, 4-Methylcyclohexanol, gamma-Octalactone, 2-Heptanone
National Category
Ecology Organic Chemistry
Research subject
Natural Science, Ecological chemistry
Identifiers
urn:nbn:se:lnu:diva-79751 (URN)10.1016/j.ibmb.2018.10.004 (DOI)000452814900005 ()30401626 (PubMedID)
Available from: 2019-01-23 Created: 2019-01-23 Last updated: 2019-01-23Bibliographically approved
Harper, A. R., Unelius, C. R., Townsend, R. J. & Suckling, D. M. (2017). Dose reduction and alternatives to the phenol pheromone in monitoring and management of the grass grub Costelytra zealandica. Pest Management Science, 73(11), 2252-2258
Open this publication in new window or tab >>Dose reduction and alternatives to the phenol pheromone in monitoring and management of the grass grub Costelytra zealandica
2017 (English)In: Pest Management Science, ISSN 1526-498X, E-ISSN 1526-4998, Vol. 73, no 11, p. 2252-2258Article in journal (Refereed) Published
Abstract [en]

BACKGROUNDEndemic New Zealand grass grub Costelytra zealandica is a pest of introduced pasture that uses phenol as a sex pheromone. The pheromone could be used to monitor and manage grass grub populations, but the irritating properties and toxicity of phenol for human handlers, as well as the possible ecotoxicological effects, pose obstacles to the deployment of the pheromone. This study aimed to limit the use of phenol by dose-response studies and investigation into alternative attractants and synergists to phenol. RESULTSNo difference in trap catch was seen across the range of 1-100mg of phenol, while rates below this (0.001-0.1mg) caused a large drop in catches. Our results indicated that 1mg loading in lures was enough to indicate beetle presence over 1 week. 4-Hydroxybenzaldehyde and p-cresol proved unattractive in this study, both as single attractants and as synergists with phenol. Phenyl acetate, phenyl benzoate and diphenyl carbonate all formed phenol under hydrolytic conditions to act as successful propheromones, while phenyl acetate was found to be as attractive as phenol on its own. CONCLUSIONThis study described several ways to reduce or avoid the use of phenol in the field while maintaining lure effectiveness. (c) 2017 Society of Chemical Industry

Place, publisher, year, edition, pages
Wiley-Blackwell, 2017
Keywords
grass grub, Costelytra zealandica, pheromone, monitoring, attractant, phenol, propheromone, phenyl acetate, phenyl benzoate, diphenyl carbonate, 4-hydroxybenzaldehyde, p-cresol, trapping
National Category
Ecology Chemical Sciences
Research subject
Natural Science, Ecological chemistry
Identifiers
urn:nbn:se:lnu:diva-68551 (URN)10.1002/ps.4599 (DOI)000412079400009 ()28444864 (PubMedID)
Available from: 2017-11-01 Created: 2017-11-01 Last updated: 2017-11-01Bibliographically approved
Bergström, M., Ganji, S., Naidu Veluru, R. & Unelius, C. R. (2017). N-Iodosuccinimide (NIS) in Direct Aromatic Iodination. European Journal of Organic Chemistry (22), 3234-3239
Open this publication in new window or tab >>N-Iodosuccinimide (NIS) in Direct Aromatic Iodination
2017 (English)In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 22, p. 3234-3239Article in journal (Refereed) Published
Abstract [en]

N-Iodosuccinimide (NIS) in pure trifluoroacetic acid (TFA) offers a time-efficient and general method for the iodination of a wide range of mono-and disubstituted benzenes at room temperature, as demonstrated in this paper. The starting materials were generally converted into mono-iodinated products in less than 16 hours at room temperature, without byproducts. A few deactivated substrates needed addition of sulfuric acid to increase the reaction rate. Another exception was methoxybenzenes that preferentially were iodinated by NIS in acetonitrile with only catalytic amounts of TFA.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2017
Keywords
Iodine-mediated reactions, Regioselectivity, Iodination, Electrophilic substitution, Arenes
National Category
Organic Chemistry
Research subject
Chemistry, Organic Chemistry
Identifiers
urn:nbn:se:lnu:diva-66906 (URN)10.1002/ejoc.201700173 (DOI)000403682000014 ()
Available from: 2017-07-14 Created: 2017-07-14 Last updated: 2018-05-17Bibliographically approved
Bohman, B., Flematti, G. R. & Unelius, C. R. (2017). Practical one-pot stereospecific preparation of vicinal and 1,3-diols. Tetrahedron Letters, 58(1), 75-77
Open this publication in new window or tab >>Practical one-pot stereospecific preparation of vicinal and 1,3-diols
2017 (English)In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 58, no 1, p. 75-77Article in journal (Refereed) Published
Abstract [en]

A facile one-pot synthesis providing vicinal diols and 1,3-diols in >95% stereoisomeric purity from commercially available enantiopure hydroxy esters has been developed. The esters were reduced with DIBALH and alkylated in situ with 4-pentenylmagnesium bromide, which after workup generated the title diols as diastereomeric pairs. These pairs were easily separated by preparative chromatography, affording products with retained stereoisomeric purity from the starting materials. This method represents an expedient preparation of many common natural products, such as cerambycid beetle pheromones and intermediates towards bicyclic acetal bark beetle pheromones. (C) 2016 Elsevier Ltd. All rights reserved.

Keywords
Diols, DIBALH, Grignard, Acetals, Pheromone
National Category
Biological Sciences
Research subject
Natural Science, Ecological chemistry
Identifiers
urn:nbn:se:lnu:diva-60803 (URN)10.1016/j.tetlet.2016.11.101 (DOI)000392038800018 ()
Available from: 2017-02-21 Created: 2017-02-21 Last updated: 2018-05-31Bibliographically approved
Unelius, C. R., Suckling, D. M., Brown, R. L., Jósvai, J. K. & El-Sayed, A. M. (2016). Combining odours isolated from phylogenetically diverse sources yields a better lure for yellow jackets. Pest Management Science, 72(4), 760-769
Open this publication in new window or tab >>Combining odours isolated from phylogenetically diverse sources yields a better lure for yellow jackets
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2016 (English)In: Pest Management Science, ISSN 1526-498X, E-ISSN 1526-4998, Vol. 72, no 4, p. 760-769Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Invasive wasps have major impacts on bird populations and other biodiversity in New Zealand beech forests, and new solutions are needed for their management. Baits were combined from four phylogenetically diverse sources (protein and carbohydrate) to improve attraction to a level that could be used as the basis for more powerful attract-and-kill systems. Many compounds from honey, scale insect honeydew, fermenting brown sugar and green-lipped mussels were highly attractive and, when combined, outcompeted known attractants.

RESULTS: The equivolumetric lure (equal parts of 3-methylbut-1-yl acetate, 2-ethyl-1-butanol, 1-octen-3-ol, 3-octanone, methyl phenylacetate and heptyl butanoate), gave a 5-10-fold improvement over the known attractant, octyl butanoate, and other previously patented lures. An economically optimised lure of the same compounds, but in a ratio of 2:1.6:1:1:2:2.4, was equally attractive as the equal-ratio lure. Pilot mass trapping attempts with this latter lure revealed that >400 wasps trap(-1)  day(-1) could be caught at the peak of the season.

CONCLUSION: The new lures are comprised of compounds from animals, plants and fungi, thus targeting the omnivorous behaviour of these wasps. © 2015 Society of Chemical Industry.

National Category
Ecology
Research subject
Natural Science, Ecological chemistry
Identifiers
urn:nbn:se:lnu:diva-47108 (URN)10.1002/ps.4050 (DOI)000371543900015 ()26017013 (PubMedID)2-s2.0-84959233188 (Scopus ID)
External cooperation:
Available from: 2015-11-10 Created: 2015-11-10 Last updated: 2017-12-01Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-7158-6393

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