| 1. |
- 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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| 2. |
- Harvey, Deborah J., et al.
(författare)
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Making the invisible visible : Determining an accurate national distribution of Elater ferrugineus in the United Kingdom using pheromones
- 2017
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Ingår i: Insect Conservation and Diversity. - : Wiley. - 1752-458X .- 1752-4598. ; 10:4, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- To date, conservation-status saproxylic beetle species in the UK have been monitored by chance findings or by monitor-based observational studies. Here, using Elater ferrugineus as our target species, we present the first national distribution survey carried out in the UK or across mainland Europe on such a species using chemicals produced by the insect. Over 3 years, mark-release-recapture studies were performed across the UK, using 416 lured (pheromone) traps monitored by volunteer recorders; the first survey in Europe to do so. Traps were baited with 7-methyloctyl- (Z)-4-decenoate, a compound previously identified as a female sex pheromone. The results were used to plot a distribution map and investigate factors that may influence the distribution, including summer temperatures, possible habitat availability and larval food source. The survey revealed a south-eastern distribution of E. ferrugineus in the UK, which was suggested by previous casual studies. A correlative model was fitted to the data, indicating that 55% of the variation in the distribution of E. ferrugineus was explained by climatic variables (temperature and wind speed).
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| 3. |
- Heydorn, Per, et al.
(författare)
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Long-term rearing affects pheromone-mediated flight behaviour of the Indian meal moth, Plodia interpunctella
- 2019
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Ingår i: Journal of Applied Entomology. - : Wiley. - 0931-2048 .- 1439-0418. ; 143:10, s. 1193-1195
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Tidskriftsartikel (refereegranskat)abstract
- The pest Plodia interpunctella (Hübner) is reared in many research laboratories. In a culture established in 1996, attraction of males to the female-produced sex pheromone in flight tunnel assays gradually decreased after ≈15 years of rearing. A new culture was established to enable comparison with the old culture regarding traits associated with mate finding. Female calling activity, pheromone titre and male antennal response to pheromone components did not differ between cultures. In contrast, very few males from the old culture reached the pheromone source in flight tunnel assays compared with 61%–81% of males from the other culture. Our results highlight the importance of maintaining viable insect cultures for research purposes and suggest frequent evaluation of traits involved in chemical communication in such cultures to ensure reliable results in experiments.
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| 4. |
- Jakobsson, Johan, et al.
(författare)
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Visual cues of oviposition sites and spectral sensitivity of Cydia strobilella L.
- 2017
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Ingår i: Journal of Insect Physiology. - : Elsevier BV. - 0022-1910. ; 101, s. 161-168
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Tidskriftsartikel (refereegranskat)abstract
- We investigated whether the spruce seed moth (Cydia strobilella L., Tortricidae: Grapholitini), an important pest in seed orchards of Norway spruce (Picea abies (L.) Karst.), can make use of the spectral properties of its host when searching for flowers to oviposit on. Spectral measurements showed that the flowers, and the cones they develop into, differ from a background of P. abies needles by a higher reflectance of long wavelengths. These differences increase as the flowers develop into mature cones. Electroretinograms (ERGs) in combination with spectral adaptation suggest that C. strobilella has at least three spectral types of photoreceptor; an abundant green-sensitive receptor with maximal sensitivity at wavelength λmax = 526 nm, a blue-sensitive receptor with λmax = 436 nm, and an ultraviolet-sensitive receptor with λmax = 352 nm. Based on our spectral measurements and the receptor properties inferred from the ERGs, we calculated that open flowers, which are suitable oviposition sites, provide detectable achromatic, but almost no chromatic contrasts to the background of needles. In field trials using traps of different spectral properties with or without a female sex pheromone lure, only pheromone-baited traps caught moths. Catches in baited traps were not correlated with the visual contrast of the traps against the background. Thus, visual contrast is probably not the primary cue for finding open host flowers, but it could potentially complement olfaction as a secondary cue, since traps with certain spectral properties caught significantly more moths than others.
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| 5. |
- Lassance, Jean Marc, et al.
(författare)
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Pheromones and Barcoding Delimit Boundaries between Cryptic Species in the Primitive Moth Genus Eriocrania (Lepidoptera : Eriocraniidae)
- 2019
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 45:5-6, s. 429-439
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Tidskriftsartikel (refereegranskat)abstract
- Animal classification is primarily based on morphological characters, even though these may not be the first to diverge during speciation. In many cases, closely related taxa are actually difficult to distinguish based on morphological characters alone, especially when there is no substantial niche separation. As a consequence, the diversity of certain groups is likely to be underestimated. Lepidoptera –moths and butterflies– represent the largest group of herbivorous insects. The extensive diversification in the group is generally assumed to have its origin in the spectacular radiation of flowering plants and the resulting abundance of ecological niches. However, speciation can also occur without strong ecological divergence. For example, reproductive isolation can evolve as the result of divergence in mate preference and the associated pheromone communication system. We combined pheromone trapping and genetic analysis to elucidate the evolutionary relationships within a complex of primitive moth species (Lepidoptera: Eriocraniidae). Mitochondrial and nuclear DNA markers provided evidence that Eriocrania semipurpurella, as currently defined by morphological characters, includes three cryptic species in Northern and Western Europe. Male moths of these cryptic species, as well as of the closely related E. sangii, exhibited relative specificity in terms of their attraction to specific ratios of two major pheromone components, (2S,6Z)-nonen-2-ol and (2R,6Z)-nonen-2-ol. Our data suggest strong assortative mating in these species in the absence of apparent niche separation, indicating that Eriocrania moths may represent an example of non-ecological speciation. Finally, our study argues in favour of combining pheromone investigations and DNA barcoding as powerful tools for identifying and delimitating species boundaries.
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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. |
- Svensson, Glenn P., et al.
(författare)
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Challenges of pheromone-based mating disruption of Cydia strobilella and Dioryctria abietella in spruce seed orchards
- 2018
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Ingår i: Journal of Pest Science. - : Springer Science and Business Media LLC. - 1612-4758 .- 1612-4766. ; 91, s. 639-650
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Tidskriftsartikel (refereegranskat)abstract
- Seed orchards function as the primary source of high-quality seeds for reforestation in many European countries, but their seed yields can be severely reduced due to seed- and cone-feeding insects. We evaluated various parameters of pheromone-based mating disruption for control of the moths Cydia strobilella and Dioryctria abietella, which are major pests in European Picea abies seed orchards. We applied different types of pheromone dispensers (rubber septa or wax droplets) at different densities and heights, and with different amounts of active components, covering whole orchards or part of an orchard. The efficacy of the treatment was evaluated by analysing male captures in pheromone-baited assessment traps, and presence of larvae in cones. A dramatic decrease (94–100%) in capture of males in traps occurred in all pheromone-treated plots compared to control plots for both moth species. In contrast, a subsequent reduction in larval numbers in cones was only achieved when wax droplets were used as the dispensing formulation at high density and at the highest pheromone dose tested, and only in half of the trials for each pest species. Electrophysiological recordings using antennae of male C. strobilella indicated elevated pheromone concentrations in a treated plot versus a control plot. Our results show that mating disruption has potential to reduce cone damage in spruce seed orchards caused by C. strobilella and D. abietella, but optimisation of the technique is required to achieve consistent and efficient population suppression of these pests.
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| 8. |
- Svensson, Glenn P., et al.
(författare)
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Floral scent of joshua trees (Yucca brevifolia sensu lato) : Divergence in scent profiles between species but breakdown of signal integrity in a narrow hybrid zone
- 2016
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Ingår i: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 103:10, s. 1793-1802
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Tidskriftsartikel (refereegranskat)abstract
- PREMISE OF THE STUDY: The role of floral scent in facilitating reproductive isolation between closely related plants remains poorly understood. Yucca brevifolia and Yucca jaegeriana are pollinated by different moth species in allopatry, but in a narrow contact zone, pollinator–host specificity breaks down, resulting in hybridization between species. We explored the chemical basis for reproductive isolation and hybridization in these Joshua trees by characterizing the floral scent of each species in allopatry, analyzing scent profiles from trees in the contact zone, and matching these data with genotypic and phenotypic data. METHODS: We analyzed floral volatiles using gas chromatography–mass spectrometry, tested for species divergence of scent profiles and classified trees in the contact zone as hybrid or either parental species. We used floral and vegetative morphological data and genotypic data to classify trees and analyzed whether certain trait combinations were more correlated than others with respect to assignment of trees and whether frequencies of classified tree types differed depending on which data set was used. KEY RESULTS: The Joshua tree floral scent included oxygenated 8-carbon compounds not reported for other yuccas. The two species differed (P < 0.001) in scent profiles. In the contact zone, many hybrids were found, and phenotypic traits were generally weakly correlated, which may be explained by extensive gene flow between species or by exposure to different selection pressures. CONCLUSIONS: Although the two Joshua tree species produce distinct floral scent profiles, it is insufficient to prevent attraction of associated pollinators to both hosts. Instead, floral morphology may be the key trait mediating gene flow between species.
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| 9. |
- Svensson, Glenn P., et al.
(författare)
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Identification and field evaluation of (E)-11,13-tetradecadienal as sex pheromone of the strawberry tortrix (Acleris comariana)
- 2019
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Ingår i: Journal of Applied Entomology. - : Wiley. - 0931-2048 .- 1439-0418. ; 143:5, s. 535-541
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Tidskriftsartikel (refereegranskat)abstract
- The strawberry tortrix (Acleris comariana Lienig and Zeller) (Lepidoptera: Tortricidae), is a major pest of strawberry in Denmark and southern Sweden. Chemical and electrophysiological analyses revealed a single compound, (E)-11,13-tetradecadienal (E11,13-14:Ald), in gland extracts of females eliciting a strong antennal response in conspecific males. Also (Z)-11,13-tetradecadienal (Z11,13-14:Ald) was found to be antennally active, but not detected in gland extracts. The corresponding alcohol and acetate of E11,13-14:Ald, which are biologically active in other Acleris species, were not produced by females and did not trigger electrophysiological response in males. Trapping experiments at a commercial strawberry farm in southern Sweden showed that E11,13-14:Ald and Z11,13-14:Ald, alone or in combination, attracted large numbers of males. Trap catches increased with increasing dose of E11,13-14:Ald, with traps baited with 100 µg and 1,000 µg being most attractive. Our results confirm the widespread use of E11,13-14:Ald as a key sex pheromone component in the genus Acleris. The identification of a highly attractive sex pheromone is a first step in developing pheromone-based methods for monitoring and control of A. comariana in European strawberry production.
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| 10. |
- Tröger, Armin, et al.
(författare)
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The Pattern of Straight Chain Hydrocarbons Released by Yucca Flowers (Asparagaceae)
- 2019
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 45:1, s. 46-49
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Tidskriftsartikel (refereegranskat)abstract
- The hydrocarbon pattern in the floral scent of Yucca species was found to comprise a group of unbranched, mid-chain alkanes, alkenes, and an alkadiene. In Y. reverchonii, highly dominant (Z)-8-heptadecene is accompanied by (6Z,9Z)-6,9-heptadecadiene and heptadecane as minor components and by traces of other saturated and unsaturated hydrocarbons with similar chain length. Some of these volatiles proved to be perceived by the antennae of Tegeticula cassandra (pollinating seed-eater of Yucca) and Prodoxus decipiens (herbivore on Yucca). The possible biosynthesis of the compounds is discussed.
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