SwePub - sökning: L773:1872 8855 OR L773:1872 88...

Numrering	Referens	Omslagsbild	Hitta
1.	Andersson, Petter, et al. (författare) Immigration of olfactory searching insects into host plant patches : testing scaling rules for olfactory information 2011 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 5, s. 269-277 Tidskriftsartikel (refereegranskat)abstract Herbivorous insects are commonly faced with host plants being distributed in scattered patches across a landscape. Immigration rates into habitat patches may strongly depend on the sensory cues used in the patch location process, and immigration rates of insects can be predicted based on the scaling of sensory cues. Here, we tested recent estimates of the scaling of olfactory information to patch size, which predicts a scaling coefficientf z = -0.5 (A^z, where A = patch size, z = scaling coefficient). We predicted that immigration rates of olfactory searching insects into patches of different sizes should scale according to the estimated slope. We investigated attraction of the weevils Cionus tuberculosus and Cionus scrophulariae to odors from figwort Scrophularia nodosa and quantified immigration rates of weevils into differently sized patches. We also investigated oviposition rates of the sawfly Tenthredo scrophulariae. The slope in the regression between density and patch size for herbivores was then compared with the predicted scaling coefficient. Using olfactometers, we found that weevils were attracted to figwort odors. Weevil densities were significantly affected by patch size, and the slope in the relationship between density and patch size was z = -0.53. The slope in the relationship between larval densities of sawflies and patch size was less negative with a slope of z = -0.15, indicating differences in search behavior compared with the weevils. The density–patch size relationship for the weevils closely matched the predicted slope and supported the previous estimations of the scaling of olfactory informationto patch size.
2.	Bærholm Schnell, Ida, et al. (författare) Characterisation of insect and plant origins using DNA extracted from small volumes of bee honey 2010 Ingår i: Arthropod-Plant Interactions. - Dordrecht : Springer Science+Business Media B.V.. - 1872-8855 .- 1872-8847. ; 4:2, s. 107-116 Tidskriftsartikel (refereegranskat)abstract A DNA-based tool was validated that potentially enables the characterisation of both plant and insect of origin of small (approximately 1 ml) samples of bee honey. Using this method, mitochondrial, nuclear and chloroplast DNA (mtDNA, nuDNA, cpDNA) markers were successfully extracted, PCR amplified, and sequenced from a range of honeys, and the relative amount of plant nuDNA and cpDNA, and bee mtDNA in the samples was quantified using quantitative real-time PCR.Short, but taxonomically informative lengths of insect and plant organelle DNA could be routinely recovered from all honey samples tested, and longer organelle, and nuclear DNA sequences can be recovered from many. The data also enabled preliminary characterisation of the quality of these different DNA sources in honey. Although the absolute quantity of the different genetic markers varied considerably between sample, a general trend was observed of insect mtDNA dominating over plant organelle DNA, and with plant nuclear DNA at the lowest levels. Furthermore there was a clear correlation between the plant DNA content and the success of the PCR assays. To maximise successful characterisation of samples, future studies are recommended to focus on the use of organelle markers, and limit the size of PCR amplicons targeted, although with appropriate sample selection and assay optimisation, other approaches may be possible.
3.	Björkman, Maria, et al. (författare) Effects of plant competition and herbivore density on the development of the turnip root fly (Delia floralis) in an intercropping system 2009 Ingår i: Arthropod-plant interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 3, s. 55-62 Tidskriftsartikel (refereegranskat)abstract In this study, interactive effects of plant competition and herbivory on plant quality and herbivore development were examined in a greenhouse experiment where cabbage plants [Brassica oleracea L. var. capitata (Brassicaceae)] were intercropped with red clover [Trifolium pratense L. (Fabaceae)]. Cabbages were grown with two red clover densities and attack rates by the root feeding herbivore the turnip root fly, Delia floralis Fall. (Diptera: Anthomyiidae). Above ground and below ground cabbage biomass was reduced through intercropping and larval damage. Intercropping also resulted in lower nitrogen and higher carbon root levels compared with levels in the roots of monocultured cabbage. Furthermore, both root nitrogen and carbon levels increased with herbivory. Root neutral detergent fibre (NDF) and lignin content increased in response to both increased plant competition and higher egg densities. For lignin, an interaction effect was observed in the form of elevated levels in intercropped plants subjected to larval damage, while levels in roots of monocultured cabbage remained unchanged. The quality changes brought about by clover competition affected D. floralis development negatively, which resulted in reduced pupal weight. In addition, increased egg density also decreased larval growth. The effects on the development of D. floralis in relation to host plant quality are discussed.
4.	Crespo, Leonardo, et al. (författare) Resistance to multiple cereal aphids in wheat-alien substitution and translocation lines 2013 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 7, s. 535-545 Tidskriftsartikel (refereegranskat)abstract Rhopalosiphum padi, Schizaphis graminum, and Sitobion avenae are three of the most destructive aphid species of wheat (Triticum aestivum L.). They can significantly reduce wheat yields directly by feeding and indirectly by transmitting viruses. This study aimed to search for resistance to these aphid species among lines derived from different rye (Secale cereale) origins and from Aegilops speltoides, all in the genetic background of the wheat cultivar Pavon F76. Resistance was quantified as aphid weight (R. padi, S. avenae, and S. graminum) and the number of aphids and percentage of infested leaf area exhibiting chlorosis (S. graminum). The most resistant genotypes reduced R. padi and S. avenae weight by 24.2 and 34.3 %, respectively, at the seedling stage, compared with Pavon F76 control plants. Strong S. graminum resistance was found only in A. speltoides-derived lines, the most resistant of which (7A.7S-L5) sustained just 3 % chlorosis and reduced S. graminum colony weight by 67.7 %. One line carrying the 1AL.1RS(am) wheat-rye translocation from Amigo wheat (originally from Insave rye) reduced S. avenae weight by 23.2 and 21.8 % in seedling and adult plants, respectively. Single genotypes carrying the complete 1R chromosome or the 1RS chromosome arm derived from E12165 wheat and Presto triticale proved to be resistant to both R. padi and S. avenae at the seedling stage. Further research should be conducted to unravel the genetic basis of resistance to these aphids in 1RS genotypes. The sources of resistance identified here may be useful for incorporating multiple aphid species resistance in wheat breeding programs, particularly for R. padi and S. avenae, to which no resistant wheats have been bred.
5.	Danielsson, Marie, et al. (författare) Arthropod infestation sites and induced defence can be traced by emission from single spruce needle 2019 Ingår i: Arthropod-Plant Interactions. - : Springer. - 1872-8855 .- 1872-8847. ; 13:2, s. 253-259 Tidskriftsartikel (refereegranskat)abstract Emissions of defence chemicals from Norway spruce seedlings can be induced by feeding arthropods or by exogenous hormonal application. Some defence chemicals may attract or repel associated arthropods. The aim of this study was to show that it is possible to detect and collect stress-induced volatiles from micro sites, such as at the scale of a single needle, in vivo by using SPME. Methyl jasmonate application on the stem of Norway spruce seedlings induced emission of (E)-beta-farnesene only from the needles closest to the application site. Emissions of (E)-beta-farnesene, (E,E)-alpha-farnesene and (E)-alpha-bisabolene were only detected from needles infested by the spider mite Oligonychus ununguis. The total volatile amount detected by SPME-GC-MS reached a considerable mass of 14 ng/needle/24 h, suggesting that emission from damaged and stressed conifers might have a larger impact on the macro climate than previously estimated.
6.	Erdei, Anna, et al. (författare) Insect chemical ecology: chemically mediated interactions and novel applications in agriculture 2020 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 14, s. 671-684 Tidskriftsartikel (refereegranskat)abstract Insect chemical ecology (ICE) evolved as a discipline concerned with plant-insect interactions, and also with a strong focus on intraspecific pheromone-mediated communication. Progress in this field has rendered a more complete picture of how insects exploit chemical information in their surroundings in order to survive and navigate their world successfully. Simultaneously, this progress has prompted new research questions about the evolution of insect chemosensation and related ecological adaptations, molecular mechanisms that mediate commonly observed behaviors, and the consequences of chemically mediated interactions in different ecosystems. Themed meetings, workshops, and summer schools are ideal platforms for discussing scientific advancements as well as identifying gaps and challenges within the discipline. From the 11th to the 22nd of June 2018, the 11th annual PhD course in ICE was held at the Swedish University of Agricultural Sciences (SLU) Alnarp, Sweden. The course was made up of 35 student participants from 22 nationalities (Fig. 1a) as well as 32 lecturers. Lectures and laboratory demonstrations were supported by literature seminars, and four broad research areas were covered: (1) multitrophic interactions and plant defenses, (2) chemical communication focusing on odor sensing, processing, and behavior, (3) disease vectors, and (4) applied aspects of basic ICE research in agriculture. This particular article contains a summary and brief synthesis of these main emergent themes and discussions from the ICE 2018 course. In addition, we also provide suggestions on teaching the next generation of ICE scientists, especially during unprecedented global situations.
7.	Glinwood, Robert, et al. (författare) Airborne interactions between undamaged plants of different cultivars affect insect herbivores and natural enemies 2009 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 3, s. 215-224 Tidskriftsartikel (refereegranskat)abstract This study investigated the effects of airborne interaction between different barley cultivars on the behaviour of bird cherry-oat aphid Rhopalosiphum padi, the ladybird Coccinella septempunctata and the parasitoid Aphidius colemani. In certain cultivar combinations, exposure of one cultivar to air passed over a different cultivar caused barley to have reduced aphid acceptance and increased attraction of ladybirds and parasitoids. Parasitoids attacked aphids that had developed on plants under exposure more often than those from unexposed plants, leading to a higher parasitisation rate. Ladybirds, but not parasitoids, were more attracted to combined odours from certain barley cultivars than either cultivar alone. The results show that airborne interactions between undamaged plants can affect higher trophic levels, and that odour differences between different genotypes of the same plant species may be sufficient to affect natural enemy behaviour.
8.	Glinwood, Robert, et al. (författare) The role of visual and olfactory plant cues in aphid behaviour and the development of non-persistent virus management strategies. 2017 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 11, s. 1-13 Forskningsöversikt (refereegranskat)abstract Non-persistent viruses are transmitted by aphids in short feeding probes during the initial stages of aphid host plant selection behaviour. To control the transmission of these viruses, farmers rely on pesticides and cultural control practices, with varying success rates. As a result, there is a need for novel management practices that are more robust and specific to reducing aphid landing rates in crops. Aphid-plant-virus interactions involve a number of behaviours and processes to ensure survival of the insect vector and virus. So far, virus management tactics focused on reducing immigrating aphids in crops have emphasized the manipulation of visual rather than olfactory stimuli. An improved understanding of the synergistic or additive effects in which aphids use visual and olfactory stimuli to locate host plants could be used to improve on current non-persistent virus management tactics and develop novel strategies. The aim of this review is to evaluate current understanding of aphid vector behaviour and the ways that these behaviours have been exploited to develop management strategies, and to identify areas of research needed to further improve virus management.
9.	Höglund, Solveig, et al. (författare) Willow resistance to a galling insect is driven by a lack of induced susceptibility not an induced defense 2015 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 9, s. 447-455 Tidskriftsartikel (refereegranskat)abstract Gall-forming insects need to manipulate host plant's growth to access food resources. Because of this intimate relationship, a hypersensitive response (HR) is thought to be an important plant defense mechanism to kill the insect before a gall is formed. Few data exist, however, that unambiguously demonstrate that HR is causally linked to resistance against galling insects. Variation in Salix viminalis resistance to the gall midge Dasineura marginemtorquens is governed by only a few genes. Although the HR is considered to be an important resistance mechanism, an earlier study based on quantitative trait locus (QTL) analysis of data sets in which resistance was expressed, has shown that larval mortality is related to a single locus in a genomic region that does not contain a locus for HR, thus challenging previous suppositions that resistance is causally linked to the expression of a HR. The present study aims to test whether or not a HR causes the observed variation in willow resistance to D. marginemtorquens. By increasing the number of markers in the genomic region of interest and reanalyzing the QTL, we have enhanced the level of resolution, so permitting a more conclusive analysis than has previously been possible. The analysis identifies two genomic regions responding to gall midge attack. Importantly, the locus for resistance (measured as neonate larval mortality) and the locus for the HR are located in different regions, strongly contradicting the induced defense hypothesis. The analysis found that resistance and susceptibility were highly correlated because the allele associated with resistance was also associated with an absence of galls. It is suggested that a lack of induced susceptibility, rather than induced defense, explains the 'resistance' of S. viminalis to D. marginemtorquens.
10.	Kännaste, Astrid, et al. (författare) Infestation by a Nalepella species induces emissions of alpha- and beta-farnesenes, (-)- linalool and aromatic compounds in Norway spruce clones of different susceptibility to the large pine weevil 2008 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 2:1, s. 31-41 Tidskriftsartikel (refereegranskat)abstract The emissions of spruce grafts (Picea abies), caused by infestation of an acarid species of the genus Nalepella were investigated. Volatiles of three clones, both healthy and infested, with different susceptibility to the large pine weevil Hylobius abietis were collected by solid phase micro extraction (SPME) and analyzed by gas chromatograph coupled to mass-spectrometry (GC-MS). In addition, enantiomers of the main chiral compounds were separated by a two dimensional-gas chromatograph (2D-GC). In the characteristic flower-like fragrances emitted by the infested grafts large amounts of E-beta-farnesene, E, E-alpha-farnesene, (-)-linalool, methyl salicylate and minute amounts of benzyl alcohol, E-anethole, methyl benzoate, neral and geranial were found. All together, these compounds could explain the characteristic scent emitted by the infested seedlings. Large differences in the emissions of E-beta-farnesene, E, E-alpha-farnesene and methyl salicylate were found between but not within the clones.
11.	Lafage, Denis, et al. (författare) Responses of ground-dwelling spider assemblages to changes in vegetation from wet oligotrophic habitats of Western France 2019 Ingår i: Arthropod-Plant Interactions. - : Springer Netherlands. - 1872-8855 .- 1872-8847. ; 13:4, s. 653-662 Tidskriftsartikel (refereegranskat)abstract While many arthropod species are known to depend, directly or indirectly, on certain plant species or communities, it remains unclear to what extent vegetation shapes spider assemblages. In this study, we tested whether the activity-density, composition, and diversity of ground-dwelling spiders were driven by changes in vegetation structure. Field sampling was conducted using pitfall traps in bogs, heathlands, and grasslands of Brittany (Western France) in 2013. A total of 8576 spider individuals were identified up to the species level (for a total of 141 species), as well as all plant species in more than 300 phytosociological relevés. A generalised linear model showed that spider activity-density was negatively influenced by mean vegetation height and mean Ellenberg value for moisture. Indices of diversity (ɑ, β, and functional diversities) increased with increasing vegetation height and shrub cover. Variables driving spider composition were mean vegetation height, dwarf shrub cover, and low shrub cover (results from a redundancy analysis). Spiders, some of the most abundant arthropod predators, are thus strongly influenced by vegetation structure, including ground-dwelling species. Although later successional states are usually seen as detrimental to local biodiversity in Europe, our results suggest that allowing controlled development of the shrub layer could have a positive impact on the diversity of ground-dwelling spiders.
12.	Lenoir, Lisette (författare) Effects of ants on plant diversity in semi-natural grasslands 2009 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 3, s. 163-172 Tidskriftsartikel (refereegranskat)abstract Ants (L. niger and L. flavus) build conspicuous mounds that are covered with vegetation. The aim of this study was to investigate whether the vegetation on ant mounds in semi-natural grasslands differed from that around the mounds. Another aim was to investigate whether the changes in the vegetation on ant mounds were influenced by grazing management or by habitat characteristics, semi-dry versus moist. Here, the total number of plant species and total plant cover were lower on ant mounds than in patches off-mound. The plant cover of perennials that form rosettes was twice as high on mounds inhabited by L. niger than on those inhabited by L. flavus. Only a few plant species were restricted to either ant mounds or adjacent field and the effects of ants on the plant diversity in semi-natural grasslands seemed to be low. Grazing management did not affect the differences in the vegetation on ant mounds and in equal-sized patches off-mound, whereas habitat characteristics affected ant-induced changes in vegetation cover of some plant species.
13.	Markovic, Dimitrije, et al. (författare) Plant response to touch affects the behaviour of aphids and ladybirds : Plant touching affects aphids and ladybirds 2014 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 8, s. 171-181 Tidskriftsartikel (refereegranskat)abstract Touching between leaves of the same plant and/or by neighbouring plants is one of the most common mechanical stimuli to which an individual plant has to respond on a daily basis. The possible ecological implications of a plant’s response to touch on plant–insect interactions have not been explicitly investigated. We examined whether plant response to 1 min daily touching over a period of 6 days affects host plant acceptance by the bird cherry-oat aphid Rhopalosiphum padi L. on maize and by the black bean aphid Aphis fabae Scop. on bean, as well as olfactory preference of an aphid predator, seven-spotted ladybird Coccinella septempunctata L. Maize plants responded to touch with significant reduction in plant height, total plant biomass, leaf weight, leaf surface, shoot/ root ratio and specific leaf area (SLA), while bean plants responded with reduced stem height and reduced SLA. Both aphid species showed significantly reduced acceptance of touched plants compared with untouched plants. The two aphid species and male and female ladybirds preferred volatiles from untouched plants over those from touched plants. Volatiles in the headspace of touched and untouched plants were collected and identified. Stepwise discriminant analyses identified (E)-nerolidol and (E)-bcaryophyllene in maize and 6-methyl-5-hepten-2-one and an unidentified sesquiterpene in bean as the best discriminating compounds in the volatile profiles of touched plants. Our study suggests that touch-induced changes in plants can potentially affect host plant selection by aphids and habitat searching by ladybirds. Thus, touch-induced changes in plants may have significant effects at higher trophic levels.
14.	Mehrabi, Sara, 1982-, et al. (författare) The constitutive expression and induction of three β-1,3-glucanases by bird cherry-oat aphid in relation to aphid resistance in 15 barley breeding lines 2016 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 10:2, s. 101-111 Tidskriftsartikel (refereegranskat)abstract In this study, 15 closely related barley genotypes were analyzed for the abundance of three β-1,3-glucanase transcripts immediately before and during infestation by the bird cherry-oat aphid (Rhopalosiphum padi L.). The barley lines are doubled haploid lines in backcross (BC) generations BC1 and BC2 from a cross between cultivar Lina and a wild barley accession. Previously, they have been characterized as susceptible (S) or resistant (R) to R. padi based on their ability to support nymphal growth. Here we also tested whether resistance was manifested as reduced aphid settling on the plants. Indeed, aphid numbers were lower on R than on S lines in all cases where there were significant differences between R and S lines. The choice of β-1,3-glucanase sequences is based on earlier results comparing two S and two R genotypes, suggesting that at least two of the three studied sequences are susceptibility factors. The comparisons of transcript abundance in plants with aphids showed for two of the β-1,3-glucanase sequences that there were several cases where an S genotype had significantly higher abundance than an R genotype, and in no case did an R line have significantly higher abundance than an S line. Thus, there was some support for the idea that β-1,3-glucanase sequences are susceptibility factors in the interaction between barley and R. padi.
15.	Nilsson, Ulf, et al. (författare) Male and female Trybliographa rapae (Hymenoptera: Figitidae) behavioural responses to food plant, infested host plant and combined volatiles 2012 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 6, s. 251-258 Tidskriftsartikel (refereegranskat)abstract Many parasitoids use volatiles produced by plants as important cues during their food and host search process. We investigated the attraction of the parasitic wasp Trybliographa rapae Westwood (Hymenoptera: Figitidae) to volatiles emitted from plants infested by the cabbage root fly Delia radicum L. (Diptera: Anthomyiidae), as well as to volatiles from a nectar food plant. Behavioural choice tests showed that male parasitoids were not attracted to any volatiles from plants infested by D. radicum or from nectar plants, while females showed clear attraction to both volatile sources. Young females were more attracted to combined volatiles of host and food plants over those from only the host plant, whereas older females showed no differences in attraction to the two odour sources. This suggests that intercropping attractive flowers with host plants could potentially be used to recruit newly emerged parasitoids from surrounding fields while older parasitoids invest more energy in host location than in additional food search. Volatiles from a whole infested plant were chosen over those emitted from separated above- and below-ground parts from infested plants. It is important to consider the availability of both energy and host resources for parasitoids when designing an eco-compatible management of a vegetable crop system.
16.	Puentes, Adriana, et al. (författare) Direct effects of elevated temperature on a tri-trophic system: Salix, leaf beetles and predatory bugs 2015 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 9, s. 567-575 Tidskriftsartikel (refereegranskat)abstract The net effect of climatic change on biotic interactions will depend on how each interacting species is individually affected. Elevated temperatures are predicted to have differential effects on species across trophic levels, due to asymmetric sensitivity to temperature changes. In this study, we examined the direct effects of three temperature regimes (16, 20 and 24 A degrees C) that reflect present and, potentially, future climate conditions on the response of Salix spp. plants, an important bioenergy crop, and its most damaging herbivore (Phratora vulgatissima) and an efficient natural enemy (the omnivorous predator Orthotylus marginalis). We found that plant growth, herbivore oviposition and enemy egg-foraging rate correlated positively with temperature. In the event of elevated temperatures following global climatic changes, these species could potentially respond in tandem. Still, the strength of responses varied among species, with herbivore and natural enemy exhibiting a similar and steeper rate of response relative to plants. Additionally, the herbivore's response was influenced by plant quality with altered oviposition rates depending on whether it was fed the (previously determined) resistant Salix dasyclados or susceptible S. viminalis. This indicates that host plant chemistry has the potential to mediate differential responses to temperature. Together, our results suggest that indirect effects of elevated temperatures, leading to a disruption of trophic associations, may be less likely or less severe in this tri-trophic system.
17.	Radonjic, Andja, et al. (författare) The phytopathogen powdery mildew affects food-searching behavior and survival of Coccinella septempunctata 2018 Ingår i: Arthropod-Plant Interactions. - : SPRINGER. - 1872-8855 .- 1872-8847. ; 12:5, s. 685-690 Tidskriftsartikel (refereegranskat)abstract The diet of entomophagous coccinellids is mainly based on aphids and other food sources such as pollen, nectar, or fungal spores. Knowledge of their foraging behavior on plants infected by powdery mildew and their survival on fungal spores is currently limited. In this study, we investigated the olfactory response of Coccinella septempunctata to odor emission of barley plants infected by powdery mildew and their survival on fungal spores in the presence or absence of aphids. Odors released by powdery-mildew infected plants were more attractive for ladybirds compared to those of uninfected controls. After 3days, the survival rate of ladybirds feeding only on powdery-mildew spores was less than 50%, while for ladybirds feeding exclusively on Rhopalosiphum padi aphids, the survival rate was close to 90%. After 15days, the highest survival rate (almost 80%) was observed for ladybirds feeding on plants with both aphids and powdery mildew. Molecular analyses confirmed the presence of fungal spores in ladybird guts when feeding either on powdery mildew or on a mixed diet. Our results provide new insights into foraging behavior of entomophagous coccinellids revealing the potential of powdery mildew to be utilized as important non-essential food in a mixed diet, but also its lethal effect if consumed alone.
18.	Schiestl, Florian P., et al. (författare) Generalized olfactory detection of floral volatiles in the highly specialized Greya-Lithophragma nursery pollination system 2021 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 15:2, s. 209-221 Tidskriftsartikel (refereegranskat)abstract Volatiles are of key importance for host-plant recognition in insects. In the pollination system of Lithophragma flowers and Greya moths, moths are highly specialized on Lithophragma, in which they oviposit and thereby pollinate the flowers. Floral volatiles in Lithophragma are highly variable between species and populations, and moths prefer to oviposit into Lithophragma flowers from populations of the local host species. Here we used gas chromatography coupled with electroantennographic detection (GC-EAD) to test whether Greya moths detect specific key volatiles or respond broadly to many volatiles of Lithophragma flowers. We also addressed whether olfactory detection in Greya moths varies across populations, consistent with a co-evolutionary scenario. We analyzed flower volatile samples from three different species and five populations of Lithophragma occurring across a 1400 km range in the Western USA, and their sympatric female Greya politella moths. We showed that Greya politella detect a broad range of Lithophragma volatiles, with a total of 23 compounds being EAD active. We chemically identified 15 of these, including the chiral 6, 10, 14-trimethylpentadecan-2-one (hexahydrofarnesyl acetone), which was not previously detected in Lithophragma. All investigated Lithophragma species produced the (6R, 10R)-enantiomer of this compound. We showed that Greya moths detected not only volatiles of their local Lithophragma plants, but also those from allopatric populations/species that they not encounter in local populations. In conclusion, the generalized detection of volatiles and a lack of co-divergence between volatiles and olfactory detection may be of selective advantage for moths in tracking hosts with rapidly evolving, chemically diverse floral volatiles.
19.	Solis-Montero, L., et al. (författare) High incidence of pollen theft in natural populations of a buzz-pollinated plant 2015 Ingår i: Arthropod-Plant Interactions. - 1872-8855 .- 1872-8847. ; 9:6, s. 599-611 Tidskriftsartikel (refereegranskat)abstract More than 20,000 angiosperm species possess non-dehiscent anthers that open through small pores at the anther's tip. These flowers are visited by bees that use vibrations to remove pollen, a phenomenon known as buzz pollination. However, some floral visitors fail to transfer pollen efficiently, either through a mismatch of flower and insect size, or because they are unable to buzz-pollinate. These visitors collect pollen, but provide little or no pollination, behaving as pollen thieves. Although pollen theft is widespread in plants, few studies have quantified the incidence of pollen thieves for buzz-pollinated plants. We use observations of natural populations and floral manipulations of Solanum rostratum (Solanaceae) to investigate the incidence of pollen theft, find morphological and behavioural differences between pollinators and thieves, measure the pollination efficiency of visitors, and characterize the reproductive ecology of this herb. We found that most visitors act as thieves, with < 20 % of all bees contacting the stigma. Insect visitors that regularly failed to contact the stigma (illegitimate visitors), included buzzing and non-buzzing bees, were significantly smaller, visited fewer flowers per bout, and stayed longer in each flower than (legitimate) visitors that regularly contact the stigma. Few flowers visited solely by illegitimate visitors set fruit. Our results show that S. rostratum requires insect visitation to set seed and natural populations experience moderate pollen limitation. We conclude that insect size, relative to the flower, is the main determinant of whether a visitor acts as a pollinator or a pollen thief in S. rostratum.
20.	Tedore, Cynthia, et al. (författare) Immunological dependence of plant-dwelling animals on the medicinal properties of their plant substrates: a preliminary test of a novel evolutionary hypothesis 2015 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 9:5, s. 437-446 Tidskriftsartikel (refereegranskat)abstract We present preliminary evidence for a novel evolutionary hypothesis, i.e., that animals living on plants high in antimicrobial secondary metabolites could, via drift or selection, evolve weakened immune defenses and an immunological dependence on the antimicrobial properties of their plant substrate and/or the volatile mix in the air surrounding their plant. Animals experience immunological stress during developmental transitions, so we evaluated our hypothesis by testing for an effect of plant substrate on hatching success in the jumping spider Lyssomanes viridis, a species that constructs its egg sacs on Liquidambar styraciflua leaves. Compared with other sympatric species, L. styraciflua is known to be high in potent volatile broad-spectrum antimicrobial compounds, most notably, the monoterpene terpinen-4-ol, a well-studied antimicrobial agent known from tea tree oil. We found that L. viridis experience higher hatching success on L. styraciflua than on other sympatric species or plastic substrate controls and that L. viridis has a chemically mediated preference for this plant. In contrast to other spiders' compact, densely woven egg sacs, L. viridis' egg sacs are sparsely woven and the eggs widely spaced, maximizing the eggs' surface area exposed to volatiles coming off the leaf. Similar architectures exist in distantly related taxa, suggesting convergent evolution. Our theoretical framework and preliminary results open up an unexplored frontier-the possibility that any number of plant-dwelling species may depend upon on the antimicrobial properties of the plant tissues they inhabit.
21.	Valterova, Irena, et al. (författare) Male bumble bee pheromonal components in the scent of deceit pollinated orchids; unrecognized pollinator cues? 2007 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 1:3, s. 137-145 Tidskriftsartikel (refereegranskat)abstract The pollination of the non-rewarding Orchis pauciflora was studied. The most abundant visitors of O. pauciflora were B. terrestris queens. The fragrance of O. pauciflora inflorescence was dominated by a sesquiterpene (E)-beta-farnesene. (E,E)-alpha-Farnesene, (E)-2,3-dihydrofarnesol, geranylcitronellol, and the monoterpenes limonene and 1,8-cineol were found among less abundant constituents. The sesqui- and diterpenes detected in O. pauciflora fragrance are frequent constituents of male marking pheromones of many bumble bee species. Enantioselective analysis of O. pauciflora scent and B. terrestris male marking pheromone revealed the presence of the (S)-isomer of (E)-2,3-dihydrofarnesol in both samples, and electrophysiological experiments showed that mainly the (S)-isomer activated the antennal receptors. In field experiments, O. pauciflora inflorescences were enriched with the main compound (E)-beta-farnesene resulting in significantly increased pollinia export. We here discuss the chemical similarities between orchid and bumble bees and whether the presence of bumble bee male pheromone components in O. pauciflora fragrance increases its fitness.
22.	Weber, Daniela, et al. (författare) Genetic variation in herbivore resistance within a strawberry crop wild relative (Fragaria vesca L.) 2020 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 14, s. 31-40 Tidskriftsartikel (refereegranskat)abstract To decrease the dependency on chemical pesticides, the resistance of cultivated strawberry to pests needs to be increased. While genetic resources within domesticated varieties are limited, wild genotypes are predicted to show high heritable variation in useful resistance traits. We collected 86 wild accessions of Fragaria vesca L. from central Sweden and screened this germplasm for antibiosis (pest survival and performance) and antixenosis (pest preference) traits active against the strawberry leaf beetle (Galerucella tenella L.). First, extensive common garden experiments were used to study antibiosis traits in the sampled plant genotypes. Heritable genetic variation among plant genotypes was found for several antibiosis traits. Second, controlled cafeteria experiments were used to test for plant genetic variation in antixenosis traits. The leaf beetles avoided egg laying on plant genotypes possessing high antibiosis. This indicates a high degree of concordance between antibiosis and antixenosis and that the beetles' egg-laying behavior optimizes the fitness of their offspring. The existence of high genetic variation in key resistance traits suggests that wild woodland strawberry contains untapped resources that are sought to reduce pesticide dependence in cultivated strawberry. Given that only a very small portion of the species' distribution area was sampled, even higher variation may be expected at the continental scale. As a whole, the genetic resources identified in this study serve to strengthen the position of woodland strawberry as a key crop wild relative.
23.	Åhman, Inger, et al. (författare) Impact of herbivory and pollination on performance and competitive ability of oilseed rape transformed for pollen beetle resistance 2009 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 3, s. 105-113 Tidskriftsartikel (refereegranskat)abstract Competitive ability of transgenic oilseed rape transformed with a pea lectin gene was estimated by comparisons of its performance when grown in a mixture with its non-transgenic counterpart and when grown singly, with and without pollen beetles present. The experiments were carried out in cages, once with bumblebees as pollinators and once without. In the absence of herbivory but with the presence of bumblebees, singly grown plant lines without lectin generally performed better than lines with lectin. Pollen beetles affected plant growth and reproduction, but there were no consistent differences between the lectin and non-lectin plant lines indicating that the transgenic trait did not protect plants from pest attack. Herbivory reduced the number of seeds when bumblebees were present. In the absence of bumblebees, however, plants produced more seeds with pollen beetles than without, indicating that some pollination was carried out by the beetles. Efficient pollination affected the competitive abilities of the lines; lectin lines were more competitive with bumblebees present and the reverse was true when bumblebees were absent. In the presence of bumblebees, lectin lines gained from being grown mixed with its non-transgenic counterpart. Because the transgenic plants expressed pea lectin in developing pollen it is possible that pollen quality in those plants was reduced, which may explain why the lectin lines had an advantage over non-lectin lines when exchange of pollen between the two plant types was facilitated by bumblebees.
24.	Åhman, Inger (författare) Quantitative trait locus for resistance to the aphid Rhopalosiphum padi L. in barley (Hordeum vulgare L.) is not linked with a genomic region for gramine concentration 2020 Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 14, s. 57-65 Tidskriftsartikel (refereegranskat)abstract Gramine is an indole alkaloid found in certain grass species. Results of previous studies have diverged as to whether this compound might cause resistance to aphids or not. In a breeding program aiming to introduce resistance to the cereal pest Rhopalosiphum padi L. in barley, a cultivar has been crossed with the progenitor of cultivated barley, Hordeum vulgare ssp. spontaneum, and an F-1-derived population of doubled haploid (DH) lines was screened both for seedling gramine concentration and resistance to R. padi. The resistance was measured as individual aphid growth in the laboratory. The present study aims to determine if there is a genetic relationship between aphid growth retardation and gramine concentration. To do so, the lines were genotyped with a 384 SNP oligonucleotide pool assay and QTL analyses were performed for both traits. A previously identified aphid resistance locus on the distal part of chromosome 2HS was thereby confirmed, with resistance inherited from H. v. ssp. spontaneum, whereas one or more QTL for gramine concentration were potentially indicated on chromosome 3H, thus corroborating that the two traits are not linked genetically.
25.	Althin, Rikard, et al. (författare) Swedish employment offices: A new model for evaluating effectiveness 2010 Ingår i: European Journal of Operational Research. - : Elsevier. - 0377-2217 .- 1872-6860. ; 207:3, s. 1535-1544 Tidskriftsartikel (refereegranskat)abstract We measure how well Swedish employment offices perform in delivering the services required of them by the Swedish government. In contrast to earlier studies we use a dynamic efficiency framework, which allows us to better model the intertemporal nature of these services, explicitly allowing for placements of intermediate nature across periods. Rather than using second stage analysis to assess the effects of varying local labor market conditions and differences in client characteristics on performance, we include a measure of the office’s expected work load directly in the model. This measure, derived from duration analysis, is designed to capture the variation across offices in resources needed before an average individual can obtain employment. It is estimated from the characteristics of all unemployed individual and local labor market conditions.The empirical results demonstrate an increase in the office’s expected work loads over time and point to substantial differences in performance across offices. The results also point toward more than optimal placements in intermediate outputs such as non-matching jobs, training, and continued unemployment.

Skapa referenser, mejla, bekava och länka

Länka till träfflistan

Träfflista för sökning "L773:1872 8855 OR L773:1872 8847 "

Avgränsa träffmängd

År