| 1. |
- Svensson, Glenn, et al.
(författare)
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Chemical ecology and insect conservation: optimising pheromone-based monitoring of the threatened saproxylic click beetle Elater ferrugineus
- 2012
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Ingår i: Journal of Insect Conservation. - : Springer Science and Business Media LLC. - 1366-638X .- 1572-9753. ; 16:4, s. 549-555
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Tidskriftsartikel (refereegranskat)abstract
- Elater ferrugineus is a saproxylic click beetle inhabiting old deciduous trees in Europe. It is threatened throughout its area of distribution due to habitat loss. No efficient monitoring method has been available for this species, but observed attraction of females to (R)-(+)-γ-decalactone, which is a male-produced sex pheromone of its prey, the scarab beetle Osmoderma eremita, has led to the development of an odour lure for monitoring. In addition, four esters have recently been identified from the pheromone-producing gland in female E. ferrugineus, and a blend of these esters is highly attractive to conspecific males in the field, revealing an alternative odour-based method for monitoring this species. However, no rigorous analysis has been performed to check whether all four esters show biological activity in male E. ferrugineus, and whether its own sex pheromone is a more potent lure than the prey kairomone for monitoring of E. ferrugineus. In this study, we reinvestigated the E. ferrugineus sex pheromone, using electrophysiological and behavioural analyses, and found that only one of the esters, 7-methyloctyl (Z)-4-decenoate, is active. In addition, trapping experiments revealed that 7-methyloctyl (Z)-4-decenoate is a much more efficient attractant for male E. ferrugineus than the prey pheromone is for conspecific females, or any sex of O. eremita. With a very efficient odour lure at hand, novel information about current distribution, local population sizes, and dispersal ranges in E. ferrugineus can now be obtained, which can aid in conservation efforts to protect this threatened insect and its habitat.
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| 2. |
- 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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| 3. |
- 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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| 4. |
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| 5. |
- Larsson, Mattias C., et al.
(författare)
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Monitoring spatiotemporal variation in abundance and dispersal by a pheromone-kairomone system in the threatened saproxylic beetles Osmoderma eremita and Elater ferrugineus
- 2011
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Ingår i: Journal of Insect Conservation. - : Springer Science and Business Media LLC. - 1366-638X .- 1572-9753. ; 15:Published online 31 March, s. 891-902
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Tidskriftsartikel (refereegranskat)abstract
- Pheromone monitoring could provide unique spatial and temporal information about rare and threatened insect species for conservation purposes. Pheromone traps may be especially valuable in detecting fluctuations and declines in vulnerable species, if trap catch can be related to population density. We exploited the pheromone-kairomone system of the hermit beetle Osmoderma eremita and its predator, the red click beetle Elater ferrugineus, to monitor variation in their flight activity during 7 years (2001–2002, 2005–2009). Spatial and temporal flight activity of O. eremita and E. ferrugineus were highly correlated over individual trap replicates and trap days. Yearly flight activities of both species were correlated within two core sites included during all years of the study, and positively affected by temperature both within and between years. Flight activity could not be directly translated to variation in abundance in either species, however. Dispersal rate was likely the main factor explaining flight activity in O. eremita. Normalizing the flight activity of E. ferrugineus against that of O. eremita did not eliminate most of the variability, however, suggesting that flight activity of E. ferrugineus was governed both by dispersal rate and by population density. Higher fluctuations in population density of E. ferrugineus likely render it more vulnerable to local extinction, which may explain the greater rarity of this species. We suggest that preserving large assemblies of suitable hollow trees would be absolutely essential for buffering against stochastic population fluctuations and securing the long-term persistence of E. ferrugineus.
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| 6. |
- Larsson, Mattias, et al.
(författare)
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Pheromones for monitoring rare and threatened insects: exploiting a pheromone-kairomone system to estimate prey and predator abundance
- 2009
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Ingår i: Conservation Biology. - : Wiley. - 0888-8892 .- 1523-1739. ; 23:6, s. 1516-1525
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Tidskriftsartikel (refereegranskat)abstract
- Pheromone-based monitoring is a promising new method for assessing the conservation status of many threatened insect species. We examined the versatility and usefulness of pheromone-based monitoring by integrating a pheromone–kairomone trapping system and pitfall trapping system in the monitoring of two saproxylic beetles, the hermit beetle Osmoderma eremita (Coleoptera: Scarabaeidae) and its predator Elater ferrugineus (Coleoptera: Elateridae), which live inside hollow trees. We performed mark–recapture studies of both species with unbaited pitfall traps in oak hollows combined with pheromone-baited funnel traps suspended from oak branches to intercept dispersing individuals. For O. eremita, the integrated trapping system showed that the population in the study sites may be considerably higher than estimates based on extrapolation from pitfall trapping alone (approximately 3400 vs. 1100 or 1800 individuals, respectively). Recaptures between odor-baited funnel traps showed that males and females had similar dispersal rates, but estimating the number of dispersing individuals was problematic due to declining recapture probability between subsequent capture events. Our conservative estimate, assuming a linear decrease in capture probability, suggested that around 1900 individuals, or at least half of the O. eremita population, may perform flights from their natal host trees, representing higher dispersal rates than previous estimates. E. ferrugineus was rarely caught in pitfall traps. One hundred thirty-nine individuals, likely almost exclusively females, were caught in odor-baited funnel traps with approximately 4% recapture probability. If recapture probability over consecutive capture events follows that of O. eremita, this would correspond to a total population size of 2500–3000 individuals of the predator; similar to its supposed prey O. eremita. Our results demonstrate that pheromone-based monitoring is a valuable tool in the study of species or life-history stages that would otherwise be inaccessible.
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| 7. |
- Rahmani, Rizan, et al.
(författare)
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Identification and synthesis of putative pheromone components of the threatened salt marsh bagworm moth, Whittleia retiella (Lepidoptera: Psychidae)
- 2020
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 46, s. 115-127
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Tidskriftsartikel (refereegranskat)abstract
- Whittleia retiella (Newman, 1847) is a threatened salt marsh species of the bagworm moth family Psychidae. For its preservation it is necessary to develop efficient tools to survey its distribution and habitat requirements in order to use appropriate conservation methods. Such tools may be pheromone-based monitoring systems, which have documented efficacy in establishing the occurrence of cryptic insect species in nature. By using gas chromatography combined with electroantennographic detection (GC-EAD), we found two compounds in female W. retiella headspace samples and whole-body extracts that elicited electrophysiological activity in male antennae. Gas chromatograpy coupled with mass spectrometry (GC-MS) operating in electron impact (EI) mode and comparison of the analytical data with those of synthetic reference compounds showed the chemical structures of these putative pheromone components to be (1S)-1-methylpropyl (5Z)-dec-5-enoate and 1-methylethyl (5Z)-dec-5-enoate. Field assays using baits loaded with synthetic compounds revealed that conspecific males were attracted to (1S)-1-methylpropyl (5Z)-dec-5-enoate alone or in combination with 1-methylethyl (5Z)-dec-5-enoate, whereas 1-methylethyl (5Z)-dec-5-enoate neither attracted nor repelled males in the field assays when tested alone. This study shows the potential of using (1S)-1-methylpropyl (5Z)-dec-5-enoate for monitoring W. retiella to gather more detailed information about the geographic distribution and habitat needs of this rare moth.
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| 8. |
- Svensson, Glenn, et al.
(författare)
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Should I stay or should I go? Modelling dispersal strategies in saproxylic insects based on pheromone capture and radio telemetry: a case study on the threatened hermit beetle Osmoderma eremita
- 2011
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Ingår i: Biodiversity and Conservation. - : Springer Science and Business Media LLC. - 0960-3115 .- 1572-9710. ; 20:13, s. 2883-2902
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Tidskriftsartikel (refereegranskat)abstract
- To predict how organisms cope with habitat fragmentation we must understand their dispersal biology, which can be notoriously difficult. We used a novel, multi-pronged approach to study dispersal strategies in the endangered saproxylic hermit beetle Osmoderma eremita, exploiting its pheromone system to intercept high numbers of dispersing individuals, which is not possible with other methods. Mark-release-recapture, using unbaited pitfall traps inside oak hollows and pheromone-baited funnel traps suspended from tree branches, was combined with radio telemetry (in females only) to record displacements. Dispersal, modelled as a probability distribution of net displacement, did not differ significantly between sexes (males versus females recaptured), observation methods (females recaptured versus radio-tracked), or sites of first capture (pitfall trap in tree versus pheromone trap – distance from original dispersal point unknown). A model including all observed individuals yielded a mean displacement of 82 m with 1% dispersing1 km. Differences in body length were small between individuals captured in pitfall versus pheromone traps, indicating that dispersal is rarely a condition-dependent response in O. eremita. Individuals captured in pheromone traps were consistently lighter, indicating that most dispersal events occur relatively late in life, which agrees with trap catch data. In addition, most (79%) females captured in pheromone traps were mated, showing that females typically mate before leaving their natal tree. Our data show that integrating odour attractants into insect conservation biology provides a means to target dispersing individuals and could greatly improve our knowledge of dispersal biology in threatened species.
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| 9. |
- 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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| 10. |
- 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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