| 1. |
- Andersson, Martin N, et al.
(författare)
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Characterization of olfactory sensory neurons in the white clover seed weevil, Apion fulvipes (Coleoptera: Apionidae).
- 2012
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Ingår i: Journal of Insect Physiology. - : Elsevier BV. - 1879-1611 .- 0022-1910. ; 58:10, s. 1325-1333
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Tidskriftsartikel (refereegranskat)abstract
- Seed-eating Apion weevils (Coleoptera: Apionidae) cause large economic losses in white and red clover seed production across Europe. Monitoring and control of clover weevils would be facilitated by semiochemical-based methods. Until now, however, nothing was known about physiological or behavioral responses to semiochemicals in this insect group. Here we analyzed the antenna of the white clover (Trifolium repens L.) specialist Apion fulvipes Geoffroy with scanning electron microscopy, and used single sensillum recordings with a set of 28 host compounds to characterize 18 classes of olfactory sensory neurons (OSNs). Nine of the OSN classes responded strongly to synthetic compounds with high abundance in clover leaves, flowers, or buds. Eight classes responded only weakly to the synthetic stimuli, whereas one collective class responded exclusively to volatiles released from a crushed clover leaf. The OSNs showed a remarkable degree of specificity, responding to only one or a few chemically related compounds. In addition, we recorded a marked difference in the temporal dynamics of responses between different neurons, compounds, and doses. The identified physiologically active compounds will be screened for behavioral activity, with the ultimate goal to develop an odor-based control strategy for this pest.
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| 2. |
- Carrasco, David, et al.
(författare)
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Characterization of olfactory sensory neurons in the red clover seed weevil, Protapion trifolii (Coleoptera : Brentidae) and comparison to the closely related species P. fulvipes
- 2019
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Ingår i: Journal of Insect Physiology. - : Elsevier BV. - 0022-1910 .- 1879-1611. ; 119
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Tidskriftsartikel (refereegranskat)abstract
- Protapion trifolii and P. fulvipes (Coleoptera: Brentidae) are major pests in European clover seed production. Previous studies have reported a high host plant fidelity of these weevils for red and white clover species, respectively, driven by host plant olfactory cues. Given the specific host preferences observed in these weevils, we aimed to elucidate to which extent such selectivity is reflected in their peripheral olfactory systems. Using an electrophysiological approach, we performed the first functional characterisation of olfactory sensory neurons (OSNs) in P. trifolii to a panel of volatile compounds emitted by red clover plants, and compared the results with the reported OSN types of P. fulvipes. Nineteen OSN classes were characterized in P. trifolii, with the majority of these neurons responding strongly to common volatiles released by the host plant. Based on response profiles, eight of these OSN classes have clear matches to OSN classes in P. fulvipes. The OSN colocalisation patterns and antennal frequency of these classes are similar in the two species. Additionally, the responses of these OSNs are generally highly conserved in the two species, with clear response shifts only revealed for two of the OSN classes. These response shifts in combination with additional response dissimilarities for compounds that vary in abundance between red and white clover plants may underlie the species-specific host preferences. Further behavioural and field experiments should focus on these differentially detected compounds to elucidate their potential role in host selection and use in semiochemical-based control of these pests.
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| 3. |
- 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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| 4. |
- Hederström, Veronica, et al.
(författare)
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Dispersal and spatiotemporal distribution of Protapion fulvipes in white clover fields : implications for pest management
- 2022
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Ingår i: Journal of Pest Science. - : Springer Science and Business Media LLC. - 1612-4758 .- 1612-4766. ; 95:2, s. 917-930
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Tidskriftsartikel (refereegranskat)abstract
- Yield loss caused by insect pests remains a substantial problem in agriculture. Chemical control, with potential negative effects on non-target organisms, is still the main tool for pest management. For pest species with limited dispersal capacity, rotation of the crop in time and space has potential as an alternative management measure. This is particularly important in organic farming, where most agrochemicals are prohibited, but also relevant as a complementary pest management strategy in conventional agriculture. Clover is an important crop used for animal feed and as green manure; however, seed-eating weevils can severely limit the seed yield. We hypothesized that the previous year’s clover seed fields constitute the major sources of weevil pests. Consequently, a greater distance to, and a smaller pest load from, this source should reduce the number of weevils colonizing the new seed fields. To map population dynamics and dispersal range of Protapion fulvipes, an economically important seed weevil specialized on white clover, we conducted field studies over four years in 45 white clover seed fields. We found that P. fulvipes overwinters close to its source field and disperses to new fields in early spring the following year. Pest abundance increased with pest load in the previous year’s seed field, but decreased by 68% per km distance to the previous year’s field. Thus, separation of seed production fields between years by 2–3 km would create a spatiotemporal pest management tool to reduce the pest infestation below the estimated economic injury level.
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| 5. |
- Hederström, Veronica, et al.
(författare)
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White clover pollinators and seed set in relation to local management and landscape context
- 2024
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Ingår i: Agriculture, Ecosystems and Environment. - 0167-8809 .- 1873-2305. ; 365
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Tidskriftsartikel (refereegranskat)abstract
- Bees are declining, which is worrisome since they both have intrinsic conservation value and play a major role as pollinators in both natural and managed ecosystems. Land use change and lack of suitable habitats are often suggested as driving forces of bee decline. To propose mitigation measures to halt bee decline, it is important to understand how land use relates to bee abundance and diversity, and to explore consequences for their provision of pollination services. White clover, Trifolium repens, is an outcrossing mass-flowering crop, which could serve as an abundant, although ephemeral, food resource for bees. We investigated how the bee community in 39 fields of white clover grown for seed, related to local field management (organic, conventional without insecticides and conventional with insecticides) and landscape context (proportion semi-natural land), and how this pollinator community related to white clover seed set. The honey bee, Apis mellifera, was the most commonly observed bee species, and two generalist bumble bee species, Bombus terrestris and B. lapidarius, were the subsequently most common. We observed fewer non-Apis bees, and a lower bee species richness in organic white clover seed fields compared to conventional fields independent of insecticide treatment. Bee species richness in both conventional and organic fields were positively related to the proportion of semi-natural land in the landscape, likely because of a larger species pool in such landscapes. Initial seed set in immature inflorescences was positively related to bee abundance, whereas final seed set in mature inflorescences was unrelated to bee abundance, possibly as a consequence of seed-eating weevils consuming a large proportion of the seeds. We conclude that both bee visitation and seed set in white clover benefit from conventional management and that landscapes rich in semi-natural habitats will make future crop production more resilient. The observed positive relationship between bee abundance and initial seed set suggests that if we can mitigate pest impacts and increase bee abundance in clover seed fields, the final seed yield can be increased. Thus, bee decline should be considered and mitigated both to maintain biodiversity in general and for crop seed production specifically.
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| 6. |
- Lundin, Ola, et al.
(författare)
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The role of pollinators, pests and different yield components for organic and conventional white clover seed yields
- 2017
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Ingår i: Field Crops Research. - : Elsevier BV. - 0378-4290 .- 1872-6852. ; 210, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- A high and stable seed production of both organic and conventional white clover (Trifolium repens L.) is needed to meet market requirements. Seed yields of white clover are, however, known to vary greatly, and organic yields are often considerably lower than conventional yields. Our aim in this study was to estimate the roles of pollinators, pests and different yield components for organic and conventional white clover seed yields. We surveyed pollinators (honey bees, bumble bees and solitary bees), reared the main insect pests (Protapion fulvipes Geoffroy and Hypera spp. weevils) from flowers and measured the yield components (inflorescences per area, flowers per inflorescence, seeds per flower and weight per seed) in organic, conventional untreated and conventional insecticide treated plots in 27 white clover seed fields over two years in southernmost Sweden. Unexpectedly, densities of bees other than honey bees were higher in insecticide treated plots compared to organic plots, but pollinator densities were not related to seed set. The lower pollinator visitation in organic plots might have been caused by pest damage to the flowers, as P. fulvipes and Hypera spp. weevils were more common in organic plots than in conventional insecticide treated plots. The abundances of both P. fulvipes and Hypera spp. weevils were negatively related to seed set, with P. fulvipes being most damaging for seed set. Seed yield was considerably lower (42%) in organic plots compared to conventional insecticide treated plots, and this was driven by a lower (36%) seed set. Taken together, our results indicate that pollinator densities are not limiting yields in either conventional or organic white clover seed production, whereas P. fulvipes crop damage is an important factor limiting organic yields via negative effects on seed set. Research efforts to raise white clover seed yield with minimized environmental impacts should include a focus on integrated pest management of P. fulvipes, including the development of control methods accepted in organic farming.
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| 7. |
- Nyabuga, Franklin, et al.
(författare)
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Field Abundance Patterns and Odor-Mediated Host Choice by Clover Seed Weevils, Apion fulvipes and Apion trifolii (Coleoptera: Apionidae)
- 2015
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Ingår i: Journal of Economic Entomology. - : Oxford University Press (OUP). - 0022-0493 .- 1938-291X. ; 108:2, s. 492-503
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Tidskriftsartikel (refereegranskat)abstract
- The clover seed weevils Apion fulvipes Geoffroy, 1785 and Apion trifolii L., 1768 (Coleoptera: Apionidae) cause major losses to seed production of white clover (Trifolium repens L.) and red clover (Trifolium pratense L.), respectively. Clover is important as animal forage and an alternative to inorganic fertilizers. Because clover is mainly pollinated by bees, the use of insecticides in management of these weevils is discouraged. To gain basic knowledge for development of alternative management strategies, we investigated weevil field abundance over two growing seasons, as well as feeding and olfactory host preferences by A. fulvipes and A. trifolii. Field trap catches in southern Sweden revealed that white clover was dominated by A. fulvipes and red clover by A. trifolii. For both weevil species, female catches were positively correlated to the number of clover buds and flowers in the field. In feeding and olfactory bioassays, females of A. fulvipes and A. trifolii showed a preference for T. repens and T. pratense, respectively. However, the feeding preference was lost when the antennae were removed, indicating a significant role of olfaction in host choice. Male weevils of both species did not show clear olfactory or feeding preferences for host plant species. The field study and laboratory bioassays demonstrate that, at least for female weevils, olfaction is important for selection of host plants. We discuss these novel results in the context of managing these important pests of clover by exploiting olfaction and behavioral attraction to host plant volatiles.
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| 8. |
- Ottosson, Niklas, et al.
(författare)
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The protonation state of small carboxylic acids at the water surface from photoelectron spectroscopy
- 2011
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 13:26, s. 12261-12267
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Tidskriftsartikel (refereegranskat)abstract
- We report highly surface sensitive core-level photoelectron spectra of small carboxylic acids (formic, acetic and butyric acid) and their respective carboxylate conjugate base forms (formate, acetate and butyrate) in aqueous solution. The relative surface propensity of the carboxylic acids and carboxylates is obtained by monitoring their respective C1s signal intensities from a solution in which their bulk concentrations are equal. All the acids are found to be enriched at the surface relative to the corresponding carboxylates. By monitoring the PE signals of acetic acid and acetate as a function of total concentration, we find that the protonation of acetic acid is nearly complete in the interface layer. This is in agreement with literature surface tension data, from which it is inferred that the acids are enriched at the surface while (sodium) formate and acetate, but not butyrate, are depleted. For butyric acid, we conclude that the carboxylate form co-exists with the acid in the interface layer. The free energy cost of replacing an adsorbed butyric acid molecule with a butyrate ion at 1.0 M concentration is estimated to be > 5 kJ mol(-1). By comparing concentration dependent surface excess data with the evolution of the corresponding photoemission signals it is furthermore possible to draw conclusions about how the distribution of molecules that contribute to the excess is altered with bulk concentration.
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| 9. |
- Wang, Hong-Lei, et al.
(författare)
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Identification of the sex pheromone of the spruce seed moth, Cydia strobilella L.
- 2010
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 1573-1561 .- 0098-0331. ; 36:3, s. 305-313
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Tidskriftsartikel (refereegranskat)abstract
- The spruce seed moth, Cydia strobilella L., is a serious pest on cones of spruce (Picea spp.) in the Holarctic region. Previous studies from different parts of its area of distribution have reported conflicting results on the composition of its sex pheromone. By gas chromatography with electroantennographic detection, coupled gas chromatography-mass spectrometry, a Y-tube olfactometer bioassay, and field trials, the sex pheromone of Swedish populations of the species was identified as (8E,10E)-dodecadienyl acetate and (8E,10Z)-dodecadienyl acetate. About 0.5 pg of each pheromone component was extracted per female. The most attractive blend of EE- and EZ-isomers was about 6:4, respectively, and 0.3 microg of the blend per rubber septum was the most attractive dosage for field trapping. Monounsaturated components previously reported as sex pheromone components/attractants for C. strobilella, (E)-8-dodecenyl acetate in Canadian populations and (Z)-8-dodecenol in Polish and Dutch populations, did not attract any C. strobilella in this study. Large numbers of C. jungiella Clerck were trapped by using (8E,10Z)-dodecadienyl acetate alone, whereas (Z)-8-dodecenol attracted Pammene splendidulana Guenée and P. rhediella Clerck.
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| 10. |
- Westberg, Sara, et al.
(författare)
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Treatment Efficacy and Immune Stimulation by AdCD40L Gene Therapy of Spontaneous Canine Malignant Melanoma
- 2013
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Ingår i: Journal of immunotherapy (1997). - 1524-9557 .- 1537-4513. ; 36:6, s. 350-358
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Tidskriftsartikel (refereegranskat)abstract
- Malignant melanoma is a serious disease in both humans and dogs, and the high metastatic potential results in poor prognosis for many patients. Its similarities with human melanoma make spontaneous canine melanoma an excellent model for comparative studies of novel therapies and tumor biology. We report a pilot study of local adenovector CD40L (AdCD40L) immunogene treatment in 19 cases of canine melanoma (14 oral, 4 cutaneous, and 1 conjunctival). Three patients were World Health Organization stage I, 2 were stage II, 10 stage III, and 4 stage IV. One to 6 intratumoral injections of AdCD40L were given every 7 days, followed by cytoreductive surgery in 9 cases and only immunotherapy in 10 cases. Tumor tissue was infiltrated with T and B lymphocytes after treatment, suggesting immune stimulation. The best overall response included 5 complete responses, 8 partial responses, and 4 stable and 2 progressive disease statuses according to the World Health Organization response criteria. Median survival was 160 days (range, 20-1141 d), with 3 dogs still alive at submission. Our results suggest that local AdCD40L therapy is safe and could have beneficial effects in dogs, supporting further treatment development. Clinical translation to human patients is in progress.
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