| 1. |
- Anderbrant, Olle, et al.
(författare)
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Pheromone of the elm bark beetle Scolytus laevis (Coleoptera Scolytidae) : stereoisomers of 4-methyl-3-heptanol reduce interspecific competition
- 2010
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Ingår i: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 20:3, s. 179-187
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Tidskriftsartikel (refereegranskat)abstract
- Stereoisomers of 4-methyl-3-heptanol (MH) are pheromone components of several Scolytus bark beetles. The elm bark beetle Scolytus laevis (Coleoptera: Scolytidae) has in previous studies been caught in traps baited with commercial MH containing all four stereoisomers, but the lure has been considered a weak attractant. In this study, we addressed the question whether stereospecific responses by S. laevis to stereoisomers of MH might contribute to its niche separation from other sympatric Scolytus species. Using GC-MS, we analyzed extracts of hindguts and abdomens from male and female S. laevis and the sympatric S. triarmatus. We also tested all four MH-stereoisomers individually and in combinations in the field to determine their role for S. laevis. All four stereoisomers were synthesized via a boronic ester method with 1,2-dicyclohexylethanediol as chiral director. In addition, the (3S,4R)-stereoisomer of MH was prepared through enantioselective, lipase-mediated transesterification of a mixture of the four stereoisomers of MH. Females of both species contained small amounts of syn-MH, and males contained trace amounts of anti-MH. The anti stereoisomer (3R,4S)-MH was attractive to male and female S. laevis, whereas the syn stereoisomer (3S,4S)-MH acted as an inhibitor or deterrent and reduced the catch when added to the attractive isomer. The syn isomer is the main aggregation pheromone component of the larger and sympatric S. scolytus and possibly also of S. triarmatus. The avoidance response of S. laevis to the (3S,4S)-stereoisomer may reduce interspecific competition for host trees.
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| 2. |
- Anderbrant, Olle, et al.
(författare)
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Release of sex pheromone and its precursors in the pine sawfly Diprion pini (Hym., Diprionidae)
- 2005
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Ingår i: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 15:3, s. 147-151
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Tidskriftsartikel (refereegranskat)abstract
- The first identification of a sex pheromone of a pine sawfly (Hymenoptera, Diprionidae) dates back almost thirty years. Since then, female-produced pheromones of over twenty diprionid species have been investigated by solvent extraction followed by separation and identification. However, no study has shown what the females actually release. Collection of airborne compounds using absorbtion on charcoal filter as well as solid phase microextraction (SPME) followed by analysis employing gas chromatography combined with mass spectrometry (GC-MS), revealed an unusual system in Diprion pini, in which the pheromone precursor alcohol, 3,7-dimethyl-2-tridecanol, is released together with acetic, propionic, butyric and isobutyric acids. The corresponding acetate, propionate and butyrate esters of 3,7-dimethyl-2-tridecanol were also found in the samples. All esters were electrophysiologically active, and the propionate and isobutyrate were attractive in trapping experiments. Based on these and earlier reported results, it seems that at least in part of its range, the pheromone response of D. pini is not very specific with regard to the functional group, as long as this is an ester.
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| 3. |
- Axelsson, Petter, et al.
(författare)
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Leaf ontogeny interacts with Bt modification to affect innate resistance in GM aspens
- 2011
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Ingår i: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 21:3, s. 161-169
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Tidskriftsartikel (refereegranskat)abstract
- Bioassays with a non-target slug (Deroceras spp.) and chemical analyses were conducted using leaf tissue from already existing genetically modified insect-resistant aspen trees to examine whether genetic modifications to produce Bacillus thuringiensis (Bt) toxins could affect plant phytochemistry, which in turn might influence plant-herbivore interactions. Three major patterns emerged. First, two independent modifications for Bt resistance affected the phytochemical profiles of leaves such that both were different from the isogenic wild-type (Wt) control leaves, but also different from each other. Among the contributors to these differences are substances with a presumed involvement in resistance, such as salicortin and soluble condensed tannins. Second, bioassays with one Bt line suggest that the modification somehow affected innate resistance ("Innate" is used here in opposition to the "acquired" Bt resistance) in ways such that slugs preferred Bt over Wt leaves. Third, the preference test suggests that the innate resistance in Bt relative to Wt plants may not be uniformly expressed throughout the whole plant and that leaf ontogeny interacts with the modification to affect resistance. This was manifested through an ontogenetic determined increase in leaf consumption that was more than four times higher in Bt compared to Wt leaves. Our result are of principal importance, as these indicate that genetic modifications can affect innate resistance and thus non-target herbivores in ways that may have commercial and/or environmental consequences. The finding of a modification-ontogeny interaction effect on innate resistance may be especially important in assessments of GM plants with a long lifespan such as trees.
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| 4. |
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| 5. |
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| 6. |
- Berg, Alexander
(författare)
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Cuticular hydrocarbons on old museum specimens of the spiny mason wasp, Odynerus spinipes (Hymenoptera: Vespidae: Eumeninae), shed light on the distribution and on regional frequencies of distinct chemotypes
- 2021
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Ingår i: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 31, s. 311-322
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Tidskriftsartikel (refereegranskat)abstract
- The mason wasp Odynerus spinipes shows an exceptional case of intrasexual cuticular hydrocarbon (CHC) profile dimorphism. Females of this species display one of two CHC profiles (chemotypes) that differ qualitatively and quantitatively from each other. The ratio of the two chemotypes was previously shown to be close to 1:1 at three sites in Southern Germany, which might not be representative given the Palearctic distribution of the species. To infer the frequency of the two chemotypes across the entire distributional range of the species, we analyzed with GC-MS the CHC profile of 1042 dry-mounted specimens stored in private and museum collections. We complemented our sampling by including 324 samples collected and preserved specifically for studying their CHCs. We were capable of reliably identifying the chemotypes in 91% of dry-mounted samples, some of which collected almost 200 years ago. We found both chemotypes to occur in the Far East, the presumed glacial refuge of the species, and their frequency to differ considerably between sites and geographic regions. The geographic structure in the chemotype frequencies could be the result of differential selection regimes and/or different dispersal routes during the colonization of the Western Palearctic. The presented data pave the route for disentangling these factors by providing information where to geographically sample O. spinipes for population genetic analyses. They also form the much-needed basis for future studies aiming to understand the evolutionary and geographic origin as well as the genetics of the astounding CHC profile dimorphism that O. spinipes females exhibit.
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| 7. |
- Bichao, H., et al.
(författare)
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Molecular receptive ranges of olfactory receptor neurones responding selectively to terpenoids, aliphatic green leaf volatiles and aromatic compounds, in the strawberry blossom weevil Anthonomus rubi
- 2005
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Ingår i: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 15:4, s. 211-226
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Tidskriftsartikel (refereegranskat)abstract
- An important question in insect-plant interactions is which of the numerous plant compounds contribute to the perception of odour qualities in herbivorous insects and are likely to be used as cues in host-searching behaviour. In order to identify which plant-produced volatiles the strawberry blossom weevil Anthonomus rubi detects, we have used electrophysiological recordings from single olfactory neurones linked to gas chromatography and mass spectrometry. We here present 15 receptor neurone types specialised for naturally produced compounds present in the host and nonhost plants and two types for two aggregation pheromone components. The active compounds were terpenoids, aromatic and aliphatic esters, alcohols and aldehydes, some of which are induced by feeding activity of the weevils. The neurones were characterised by a strong response to one or two primary odorants and weaker responses to a few others having similar chemical structure. With one exception, the molecular receptive range of each neurone type was within one chemical group. Enantiomers of linalool separated on a chiral column activated two neurone types with different enantioselectivity. Inhibition by linalool of another neurone type, excited by alpha-pinene, indicated an additional mechanism for coding the information about this compound. Altogether, detection of 54 compounds by olfactory receptor neurones is shown, of which 40 have been chemically identified in this study. Thus A. rubi has the ability to detect a large number of odorants that may be used in host selection behaviour.
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| 8. |
- Birgersson, Göran
(författare)
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Aggregation pheromones of bark beetles, Pityogenes quadridens and P-bidentatus, colonizing Scotch pine: olfactory avoidance of interspecific mating and competition
- 2013
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Ingår i: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 23, s. 251-261
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Tidskriftsartikel (refereegranskat)abstract
- The bark beetles Pityogenes bidentatus and Pityogenes quadridens (Coleoptera, Curculionidae, Scolytinae) are sibling species that feed and reproduce in bark areas on branches of Scotch pine, Pinus sylvestris. To identify aggregation pheromone components of both species, hindguts and head/thoraxes of males and females of both species feeding in hosts were extracted in pentane and analyzed by gas chromatography and mass spectrometry. Hindguts of male P. bidentatus contained grandisol as the major component along with small amounts of (4S)-cis-verbenol and other monoterpenes. Dose-response bioassays in the laboratory showed the components were attractive at 0.2 ng/min to walking beetles from a distance of a parts per thousand yen25 cm. In the field in southern Sweden, grandisol and (4S)-cis-verbenol were weakly attractive alone when released at rates of 0.05 and 0.5 mg/day, respectively, from a slow-rotating trap pair. Catch increased 3.6- to 13-fold when the two components were released together. The male proportion of the catch was 0.8 early in the flight period, declined to 0.5 on the peak flight day, and then declined further during the next 2 weeks to 0.2 on the last day of the flight period. Hindguts of male P. quadridens contained (2S,5R)- and (2S,5S)-chalcogran, as well as (E)-2-(3,3-dimethylcyclohexylidene)ethanol (E-grandlure 2) and E/Z-mixture of 2-(3,3-dimethylcyclohexylidene)acetaldehyde (grandlures 3 and 4), while female hindguts had only a trace amount of chalcogran. Laboratory studies proved E-grandlure 2 is an essential pheromone component for P. quadridens. Field bioassays with a slow-rotating trap pair in which the attractiveness of blends containing various candidate components were compared with that of less complete mixtures, showed that chalcogran and E-grandlure 2 were synergistic aggregation pheromone components of P. quadridens. Field tests also showed that grandisol (from P. bidentatus) reduced attraction of P. quadridens to its aggregation pheromone, whereas E-grandlure 2 and chalcogran (from P. quadridens) reduced response of P. bidentatus to its aggregation pheromone. Our results suggest that aggregation pheromone components from males of each species not only attract conspecifics but also aid individuals in avoiding interspecific mating and competition for food and spatial resources within the bark phloem layer.
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| 9. |
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| 10. |
- De Facci, Monica, et al.
(författare)
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Chemical composition of anal droplets of the eusocial gall-inducing thrips Kladothrips intermedius
- 2014
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Ingår i: Chemoecology. - : Springer Science and Business Media LLC. - 1423-0445 .- 0937-7409. ; 24:3, s. 85-94
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Tidskriftsartikel (refereegranskat)abstract
- The eusocial Acacia gall-inducing thrips Kladothrips intermedius (Thysanoptera: Phlaeothripinae) secretes defensive anal droplets when threatened. In addition to harmful substances, droplets of other thysanopteran species are known to contain semiochemicals such as alarm pheromones and/or repellents against enemies. Both Kl. intermedius larval stages and adult castes (soldiers and dispersers) produce anal droplets. In addition, a recent study has shown that soldier droplets may contain an alarm pheromone. Using multiple sampling methods (extraction in solvent, solid phase microextraction and direct injection), we analyzed the content of adults and second instar larvae anal droplets by gas chromatography coupled to mass spectrometry. Anal droplets comprised of a set of saturated and monounsaturated short-chain fatty acids, including three compounds with a terminal double bond (7-octenoic acid, 8-nonenoic acid and 9-decenoic acid). The latter are here reported for the first time in an insect species. In addition, putative unsaturated wax esters similar to those found in the secretion of other social insects were also detected in droplets. In order to investigate the physiological activity of the acids, single sensillum recordings were performed on adult Kl. intermedius as well as on adults of its kleptoparasite, Koptothrips dyskritus, targeting olfactory receptor neurons in the antennal sensilla basiconica. While olfactory perception of the acids in these species cannot be completely excluded, our analyses indicate that sensilla basiconica are not strongly sensitive to these droplet compounds.
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