1. Reliably predicting pest damage would allow farmers to reduce insecticide use without incurring economic losses and thus contribute to agricultural sustainability. However, means to predict pest severity are lacking. 2. We assessed... more
1. Reliably predicting pest damage would allow farmers to reduce insecticide use without incurring economic losses and thus contribute to agricultural sustainability. However, means to predict pest severity are lacking. 2. We assessed whether crop feeding injury caused by flea beetles in spring oilseed rape can be predicted from flea beetle pest densities in the previous season using 22 years of suction trap catches of flea beetles in combination with crop feeding injury data from 293 fields. 3. We found a strong positive relationship between the densities of flea beetles of the genus Phyllotreta in the summer and autumn activity period of the previous year and crop feeding injury caused by flea beetles in spring oilseed rape the following year. Autumn weather or the total cover of spring oilseed rape in the study region did not improve the prediction further. 4. Pest monitoring using suction traps is thus a promising tool to predict crop feeding injury and can reduce insecticide use in years with low pest pressures.
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Communication through airborne volatile organic compounds (VOCs) and root exudatesplays a vital role in the multifarious interactions of plants. Common ragweed (Ambrosia artemesiifolia L.) is one of the most troublesome invasive alien... more
Communication through airborne volatile organic compounds (VOCs) and root exudatesplays a vital role in the multifarious interactions of plants. Common ragweed (Ambrosia artemesiifolia L.) is one of the most troublesome invasive alien species in agriculture. Below- and boveground
chemical interactions of ragweed with crops might be an important factor in the invasive species’ success in agriculture. In laboratory experiments, we investigated the contribution of intra- and
interspecific airborne VOCs and root exudates of ragweed to its competitiveness. Wheat, soybean,
and maize were exposed to VOCs emitted from ragweed and vice versa, and the adaptation response
was measured through plant morphological and physiological traits. We observed significant changes
in plant traits of crops in response to ragweed VOCs, characterized by lower biomass production,
lower specific leaf area, or higher chlorophyll contents. After exposure to ragweed VOCs, soybean
and wheat produced significantly less aboveground dry mass, whereas maize did not. Ragweed
remained unaffected when exposed to VOCs from the crops or a conspecific. All crops and ragweed
significantly avoided root growth toward the root exudates of ragweed. The study shows that the
plant response to either above- or belowground chemical cues is highly dependent on the identity of
the neighbor, pointing out the complexity of plant–plant communication in plant communities.
chemical interactions of ragweed with crops might be an important factor in the invasive species’ success in agriculture. In laboratory experiments, we investigated the contribution of intra- and
interspecific airborne VOCs and root exudates of ragweed to its competitiveness. Wheat, soybean,
and maize were exposed to VOCs emitted from ragweed and vice versa, and the adaptation response
was measured through plant morphological and physiological traits. We observed significant changes
in plant traits of crops in response to ragweed VOCs, characterized by lower biomass production,
lower specific leaf area, or higher chlorophyll contents. After exposure to ragweed VOCs, soybean
and wheat produced significantly less aboveground dry mass, whereas maize did not. Ragweed
remained unaffected when exposed to VOCs from the crops or a conspecific. All crops and ragweed
significantly avoided root growth toward the root exudates of ragweed. The study shows that the
plant response to either above- or belowground chemical cues is highly dependent on the identity of
the neighbor, pointing out the complexity of plant–plant communication in plant communities.
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Trabajo presentado en Estocolmo (Suecia) entre el 29 de junio y el 3 de julio de 2015.Only in Sweden 360 million conifer seedlings are planted each year but a substantial proportion of these are killed by pine weevils (Hylobius abietis)... more
Trabajo presentado en Estocolmo (Suecia) entre el 29 de junio y el 3 de julio de 2015.Only in Sweden 360 million conifer seedlings are planted each year but a substantial proportion of these are killed by pine weevils (Hylobius abietis) and black spruce beetles (Hylastes cunicularius). A high survival rate is essential for a high primary production of forest raw materials and biomass. There is currently no suitable non-insecticide plant protection option for a large part of these seedlings. One option may, however, be to trigger the seedlings´ own induced defense by treating them with a plant activator at the nursery so that they are prepared when they later becomes attacked by pine weevils in the field. The induced defense is under natural conditions generally expressed after damage by, e.g. a pest insect, whereas constitutive defenses are permanently present. Constitutive defenses serves to inhibit an initial attack whereas the induced defense serves to actively and vigorously stop the attack. The induced defense is powerful but the time lag after an initial attack before the induced defenses are fully expressed may be detrimental for a plant when the pest pressure is high. This weakness of the induced defense can be circumvented by applying a plant activator to trigger the induced defense of the plant before it is exposed to attacks. There is a suitable plant activator to trigger the induced defense of conifers available. That is methyl jasmonate which is a substance that also is produced naturally when a plant is attacked. It triggers the production of traumatic resin channels and different types of chemical defense substances. In this talk I will present some recent results related to the potential of this method to protect conifer seedlings against pine weevils.Peer reviewe
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... It seems that the allelobiotic response is different from the effect caused by the stress related substances MeSA and MeJA. ... Biol Invasions 11:275–287 Field B, Jordan F, Osbourn A (2006) First encounters – deployment of... more
... It seems that the allelobiotic response is different from the effect caused by the stress related substances MeSA and MeJA. ... Biol Invasions 11:275–287 Field B, Jordan F, Osbourn A (2006) First encounters – deployment of defence-related natural products by plants. ...
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<p>Responses of winged <i>Myzus persicae</i> in olfactometer experiments when presented with test solutions containing different doses of (A) (E)-nerolidol, and (B) (3E, 7E) 4, 8, 12-trimethyl-1, 3, 7, 11-tridecatetraene... more
<p>Responses of winged <i>Myzus persicae</i> in olfactometer experiments when presented with test solutions containing different doses of (A) (E)-nerolidol, and (B) (3E, 7E) 4, 8, 12-trimethyl-1, 3, 7, 11-tridecatetraene (TMTT), alongside hexane control. Error bars indicate ± SEM. *P≤0.05 Wilcoxon test.</p
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Chemical interaction through airborne volatile organic compounds (VOCs) and root exudates plays a vital role in the mutualistic interactions between plants. In response to these chemical cues, a single plant can exhibit a multitude of... more
Chemical interaction through airborne volatile organic compounds (VOCs) and root exudates plays a vital role in the mutualistic interactions between plants. In response to these chemical cues, a single plant can exhibit a multitude of adaption responses. Nowadays, one of the most troublesome invasive alien species (IAS) in agriculture is common ragweed ( Ambrosia artemesiifolia L.), which causes severe yield losses in various crops. Given that little is known about how chemical cues of this invader contribute to its invasiveness, we investigated the effects of airborne VOCs and root exudates released by common ragweed on growth and allocation patterns of wheat, soybean and maize, and the effects of these crops on common ragweed. Exposure to VOCs released by ragweed induced a significant reduction in the aboveground dry mass of soybean and wheat, whereas maize showed no changes in its biomass production. In contrast, ragweed itself was completely unaffected when exposed to crops or a...
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Samodling av specifika sortkombinationer mobiliserar kornets forsvar mot bladloss, vilket kan vara en viktig del av ett forebyggandevaxtskydd i ekologisk produktion. Men vilka sorter ska mansamodla? Ett pagaende SLU- och Formasprojekt... more
Samodling av specifika sortkombinationer mobiliserar kornets forsvar mot bladloss, vilket kan vara en viktig del av ett forebyggandevaxtskydd i ekologisk produktion. Men vilka sorter ska mansamodla? Ett pagaende SLU- och Formasprojekt kommer ge svar.
Plants can detect the presence of their neighbours and modify their growth behaviour accordingly. But the extent to which this neighbour detection is mediated by abiotic stressors is not well known. In this study we tested the acclimation... more
Plants can detect the presence of their neighbours and modify their growth behaviour accordingly. But the extent to which this neighbour detection is mediated by abiotic stressors is not well known. In this study we tested the acclimation response of Zea mays L. seedlings through belowground interactions to the presence of their siblings exposed to brief mechano stimuli. Maize seedling simultaneously shared the growth solution of touched plants or they were transferred to the growth solution of previously touched plants. We tested the growth preferences of newly germinated seedlings toward the growth solution of touched (T_solution) or untouched plants (C_solution). The primary root of the newly germinated seedlings grew significantly less towards T_solution than to C_solution. Plants transferred to T_solution allocated more biomass to shoots and less to roots. While plants that simultaneously shared their growth solution with the touched plants produced more biomass. Results show t...
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Communication between vascular plants through volatile organic compounds (VOCs) impacts on ecosystem functioning. However, nothing is known about that between non-vascular plants. To investigate plant–plant VOCs interaction in bryophytes... more
Communication between vascular plants through volatile organic compounds (VOCs) impacts on ecosystem functioning. However, nothing is known about that between non-vascular plants. To investigate plant–plant VOCs interaction in bryophytes we exposed rare peatland moss Hamatocaulis vernicosus to VOCs of its common competitor Sphagnum flexuosum in an air-flow system of connected containers under artificial light, supplemented or unsupplemented by far-red (FR) light. When exposed to VOCs of S. flexuosum, shoots of H. vernicosus elongated and emitted six times higher amounts of a compound chemically related to β-cyclocitral, which is employed in stress signalling and allelopathy in vascular plants. The VOCs emission was affected similarly by FR light addition, possibly simulating competition stress. This is the first evidence of plant–plant VOCs interaction in non-vascular plants, analogous to that in vascular plants. The findings open new possibilities for understanding the language and...
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Foraging strategies of birds can influence trophic plant-insect networks with impacts on primary plant production. Recent experiments show that some forest insectivorous birds can use herbivore induced plant volatiles (HIPVs) to locate... more
Foraging strategies of birds can influence trophic plant-insect networks with impacts on primary plant production. Recent experiments show that some forest insectivorous birds can use herbivore induced plant volatiles (HIPVs) to locate herbivore-infested trees, but it is unclear how birds combine or prioritise visual and olfactory information when making foraging decisions. Here we investigated attraction of ground-foraging birds to HIPVs and visible prey in short vegetation on farmland in a series of foraging choice experiments. Birds showed an initial preference for HIPVs when visual information was the same for all choice options (i.e. one experimental setup had all options with visible prey, another setup with hidden prey). However, if the alternatives within an experimental setup included visible prey (without HIPV) in competition with HIPV-only, then birds preferred the visual option over HIPVs. Our results show that olfactory cues can play an important role in birds’ foraging choices when visual information contains little variation; however, visual cues are preferred when variation is present. This suggests certain aspects of bird foraging decisions in agricultural habitats are mediated by olfactory interaction mechanisms between birds and plants. We also found that birds from variety of dietary food guilds were attracted to HIPVs; hence, the ability of birds to use plant cues is probably more general than previously thought, and may influence the biological pest control potential of birds on farmland
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Biological control, or biocontrol, is the exploitation of living agents (incl. viruses) to combat pestilential organisms (incl. pathogens, pests, and weeds) for diverse purposes to provide human benefits. Thus, during the last century the... more
Biological control, or biocontrol, is the exploitation of living agents (incl. viruses) to combat pestilential organisms (incl. pathogens, pests, and weeds) for diverse purposes to provide human benefits. Thus, during the last century the practices and concepts involved have evolved in separate streams associated with distinct scientific and taxonomic disciplines. In parallel developments, there have been increasing references to biological control in industrial contexts and legislation, resulting in conceptual and terminological disintegration. The aim of this paper is to provide a global conceptual and terminological platform that facilitates future development of the field. We review use of previously suggested terms in key fields (e.g., phytopathology, entomology, and weed science), eliminate redundant terminology, identify three principles that should underpin the concept, and then present a new framework for biological control, rooted in seminal publications. The three princip...
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Aims Cultivar mixtures can increase productivity through complementarity in resource use, but reported results are often conflicting and the role of plasticity in shaping plant-plant interactions is poorly understood. We aim to determine... more
Aims Cultivar mixtures can increase productivity through complementarity in resource use, but reported results are often conflicting and the role of plasticity in shaping plant-plant interactions is poorly understood. We aim to determine if individual cultivars show different phenotypic responses when grown in a mixture, whether these responses depend on the neighboring cultivar identity, and how they contribute to variations in productivity and nitrogen (N) use. Methods Five spring barley cultivars were field-grown in pure stands and in mixtures during 2 years. Plant traits related to development, growth, N use, and reproduction were measured to identify temporal patterns of plastic responses to neighboring plants. Results Plants in mixtures were shorter and developed slower early in the season, but later on they grew faster and produced more grain than the corresponding pure stands. Some cultivars showed complementary N accumulation only when grown together with specific neighbors...
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... Frieda Prest. Isabe. Seba. Chris. Hulda Alva # # ns ns Lina ns ns ns ns ns Kara ns ns Barke # ns # ns ns ns ... J Agric Food Chem 53:86318638 Otway SJ, Hector A, Lawton JH (2005) Resource dilution effects on specialist insect... more
... Frieda Prest. Isabe. Seba. Chris. Hulda Alva # # ns ns Lina ns ns ns ns ns Kara ns ns Barke # ns # ns ns ns ... J Agric Food Chem 53:86318638 Otway SJ, Hector A, Lawton JH (2005) Resource dilution effects on specialist insect herbivores in a grassland biodiversity experiment. ...
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Research Interests: Biomass, Plant Biology, Biology, Resource Allocation, Pheromones, and 15 moreAllelopathy, Medicine, Relative Growth Rate, Growth, Experimental Botany, Plant Roots, Biomass Allocation, Biomass production, Gramineae, Specific leaf area, Plant Community, Leaf Area, Dry Weight, Hordeum vulgare L, and Mass Fractions
Increased botanical diversity can lead to suppression of insect pests. One route by which botanical diversity is increased in crops is through the occurrence of weeds, which increasingly interact with crop plants as organic production... more
Increased botanical diversity can lead to suppression of insect pests. One route by which botanical diversity is increased in crops is through the occurrence of weeds, which increasingly interact with crop plants as organic production expands. However, the mechanisms by which this might affect insect herbivores are poorly understood. This study examined whether volatile chemical interactions between weeds and barley, Hordeum vulgare L. (Poaceae), can affect plant acceptance by the bird cherry oat aphid, Rhopalosiphum padi L. (Hemiptera: Aphididae). In laboratory experiments, exposure of barley to volatiles from Chenopodium album L. (Amaranthaceae) and Solanum nigrum L. (Solanaceae) resulted in significantly reduced aphid acceptance compared with unexposed plants. In a series of field experiments in which the occurrence of weeds was manipulated in plots of barley, significantly lower aphid acceptance was recorded on barley plants grown in plots with C. album compared with barley plants in weedless plots. The results indicate that interaction between weeds and barley can affect aphid–plant interactions in the field as well as in the laboratory and provide further evidence that the effects of chemical interactions between visibly undamaged plants can extend to higher trophic levels.
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Plant volatiles provide herbivorous arthropods with information that allows them to discriminate between host and non-host plants. Volatiles may also indicate plant stress status, and natural enemies can use herbivore-induced plant... more
Plant volatiles provide herbivorous arthropods with information that allows them to discriminate between host and non-host plants. Volatiles may also indicate plant stress status, and natural enemies can use herbivore-induced plant volatiles as cues for prey location. Neighbouring plants may also make use of volatile cues to prepare for herbivore attack. Since both constitutive and inducible plant volatile emissions can be modified by plant breeding, the possibility exists to improve plant resistance against important pests both directly and indirectly via improved biological control. So far this approach has been tested only in the realm of research, predominantly using transgenic Arabidopsis with modified composition of terpenoids or C6 green leaf compounds. However, several studies have shown that it is indeed possible both to reduce herbivory and to enhance natural enemy attraction simultaneously. If such effects can be translated into increased and more stable yields in importa...
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The response of the bird cherry-oat aphid, Rhopalosiphum padi, to barley plants was investigated following exposure of the plants to root allelochemicals from the aggressive weed couch-grass, Elytrigia (Agropyron) repens. Plants were... more
The response of the bird cherry-oat aphid, Rhopalosiphum padi, to barley plants was investigated following exposure of the plants to root allelochemicals from the aggressive weed couch-grass, Elytrigia (Agropyron) repens. Plants were treated either with root exudates from living couch-grass plants or with previously identified couch-grass root compounds 15-hydroxyindole-3-acetic acid, DL-5-hydroxytryptophan, L-5-hydroxytryptophan hydrate, and 6-hydroxy-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (carboline)] either separately or in mixtures. In choice and no-choice settling tests, aphid acceptance of barley plants was significantly reduced following treatment with root exudates, and the carboline when tested alone or in combination with the other compounds. In contrast, the other compounds without the carboline were less active in reducing aphid acceptance. In a probing bioassay, individual substances were either neutral or stimulatory to aphids, indicating that the reduced ...
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Methyl salicylate (MeSA) is a volatile shown to act as an inducer of plant defense against pathogens and certain herbivores, particularly aphids. It has been shown to have potential for aphid pest management, but knowledge on its mode of... more
Methyl salicylate (MeSA) is a volatile shown to act as an inducer of plant defense against pathogens and certain herbivores, particularly aphids. It has been shown to have potential for aphid pest management, but knowledge on its mode of action is lacking, particularly induced plant-mediated effects. This study investigated the effects of exposing plants to MeSA on the host searching, host acceptance and feeding behavior of the bird cherry-oat aphid Rhopalosiphum padi. Barley plants were exposed to volatile MeSA for 24 h, after which biological effects were tested immediately after the exposure (Day 0), and then 1, 3 and 5 days after the end of the exposure. Aphid settling on MeSA-exposed plants was significantly reduced on days 0, 1 and 3, but not on day 5. In olfactometer tests, aphids preferred the odor of unexposed plants on days 1 and 3, but not on day 0 or 5. Analysis of volatiles from exposed and unexposed plants showed higher levels of MeSA from exposed plants, most likely a...
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The pine weevil ( Hylobius abietis ) is one of the most important forest pests in Europe, yet there is very little known about its detailed feeding behaviour. We study the temporal feeding pattern of individual pine weevils of both sexes... more
The pine weevil ( Hylobius abietis ) is one of the most important forest pests in Europe, yet there is very little known about its detailed feeding behaviour. We study the temporal feeding pattern of individual pine weevils of both sexes for 24 hours with two treatments, intact and girdled seedlings. Properties of a meal, such as feeding duration, size and ingestion rate are of particular interest. The shortest interval considered to separate one feeding bout from another, the meal criterion, has never been published and it is only available for a few other insect species. Video recordings are analysed for feeding behaviour (e.g. duration of feeding activity, interval length between feeding activities, movements between and within feeding scars). We measured general activity patterns as there is insufficient knowledge on the daily behavioural patterns. We thereby got an in-depth view of the pine weevil feeding activity that would otherwise be difficult to assess.
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Introduction Sevenspotted ladybird, Coccinella septempunctata (L.), has a pronounced seasonal migration rhythm, and is a very mobile species in the landscape. Adults hibernate in well recognisable sites such as ridges, hills, mountains,... more
Introduction Sevenspotted ladybird, Coccinella septempunctata (L.), has a pronounced seasonal migration rhythm, and is a very mobile species in the landscape. Adults hibernate in well recognisable sites such as ridges, hills, mountains, water towers etc. The distribution of ladybirds within such a hibernating site is patchy, and the number of ladybirds in an aggregation can be high, sometimes exceeding 200 individuals per m (Majerus 1994; Hodek and Honek 1996). This aggregated distribution may be mediated by a putative aggregation pheromone, pyrazine (Al abassi et al 1998). The seasonal migrations to and from hibernating sites are important traits in the population biology of the sevenspotted ladybird, and the mobility and dynamic redistribution of adults in the landscape has inspired investigations of both the principles and mechanistic aspects of foraging behaviour. In a recent review, the general principle for the foraging behaviour of C. septempunctata is described as a ‘journey...
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BACKGROUND The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) movement in stored products is mediated by food volatiles and other semiochemicals. RESULTS In 2-way olfactometer assays, T. castaneum was more... more
BACKGROUND The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) movement in stored products is mediated by food volatiles and other semiochemicals. RESULTS In 2-way olfactometer assays, T. castaneum was more attracted to wheat bran previously infested with conspecifics than to uninfested bran. Chemical analysis showed that 1-pentadecene was present in the headspace of T. castaneum infested wheat bran, but not detectable in the headspace of uninfested bran. An olfactometer was used to test the effect on T. castaneum behavior of 1-pentadecene, and of volatiles from wheat bran with and without 1-pentadecene. The lowest concentration of 1-pentadecene exhibited an attractive effect, compared to the control (n-hexane). Slightly higher concentrations showed a neutral effect, while the highest concentrations repelled T. castaneum. Wheat bran with a low 1-pentadecene concentration was more attractive than wheat bran alone, whereas higher concentrations of 1-pentadecene were repellent. CONCLUSION The results provide important information on intraspecific, semiochemical-mediated behaviour in T. castaneum, which could potentially be used to develop new methods to monitor the flour beetles in stored products.
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Tribolium castaneum is one of the most economically important insects that damages stored products. The effects of several infested or uninfested raw feed materials (wheat bran, coarse wheat meal, corn feed flour), feed products (compound... more
Tribolium castaneum is one of the most economically important insects that damages stored products. The effects of several infested or uninfested raw feed materials (wheat bran, coarse wheat meal, corn feed flour), feed products (compound feed for pigs and for laying hens) and flour mixed with brewer's yeast on the food-searching behaviour of T. castaneum adults were studied in a total of 48 combinations. Preference and olfactometer tests revealed that all the tested uninfested and intraspecific infested substrates were significantly more attractive to T. castaneum than the control (represented by part of an arena or olfactometer arm without substrate). We determined that all infested substrates were 2–9 times more attractive than uninfested in the preference test, while in the olfactometer test, they were 3–8 times more attractive. In comparing the attractiveness of the infested and uninfested substrates, in both tests wheat bran was found to be the most attractive substrate to...
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ABSTRACTEnvironmentally induced changes in the epigenome help individuals to quickly adapt to fluctuations in the conditions of their habitats. Here we explored those changes in Arabidopsis thaliana plants subjected to multiple biotic and... more
ABSTRACTEnvironmentally induced changes in the epigenome help individuals to quickly adapt to fluctuations in the conditions of their habitats. Here we explored those changes in Arabidopsis thaliana plants subjected to multiple biotic and abiotic stresses, and identified transposable element (TE) activation in plants infested with the green peach aphid, Myzus persicae. We performed a genome-wide analysis of DNA methylation, mRNA expression, mRNA degradation and small RNA accumulation. Our results demonstrate that aphid feeding induces loss of methylation of hundreds of loci, mainly TEs. This loss of methylation has the potential to regulate gene expression and we found evidence that it is involved in the control of key plant immunity genes. Accordingly, we find that mutant plants deficient in epigenetic silencing show increased resistance to M.persicae infestation. Collectively, our results show that changes in DNA methylation play a significant role in the regulation of the plant t...
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Page 1. Plant Volatiles Mediate Tritrophic Interactions Barley, aphids and ladybirds Velemir Ninkovic Department of Entomology Uppsala Doctoral thesis Swedish University of Agricultural Sciences Uppsala 2002 Page 2. Acta ...
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Abstract Volatile organic compounds are important mediators of mutualistic interactions between plants and their physical and biological surroundings. Volatiles rapidly indicate competition or potential threat before these can take place,... more
Abstract Volatile organic compounds are important mediators of mutualistic interactions between plants and their physical and biological surroundings. Volatiles rapidly indicate competition or potential threat before these can take place, and they regulate and coordinate adaptation responses in neighbouring plants, fine‐tuning them to match the exact stress encountered. Ecological specificity and context‐dependency of plant–plant communication mediated by volatiles represent important factors that determine plant performance in specific environments. In this review, we synthesise the recent progress made in understanding the role of plant volatiles as mediators of plant interactions at the individual and community levels, highlighting the complexity of the plant receiver response to diverse volatile cues and signals and addressing how specific responses shape plant growth and survival. Finally, we outline the knowledge gaps and provide directions for future research. The complex dialogue between the emitter and receiver based on either volatile cues or signals determines the outcome of information exchange, which shapes the communication pattern between individuals at the community level and determines their ecological implications at other trophic levels.
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Plant volatiles provide herbivorous arthropods with information that allows them to discriminate between host and non-host plants. Volatiles may also indicate plant stress status, and natural enemies can use herbivore-induced plant... more
Plant volatiles provide herbivorous arthropods with information that allows them to discriminate between host and non-host plants. Volatiles may also indicate plant stress status, and natural enemies can use herbivore-induced plant volatiles as cues for prey location. Neighbouring plants may also make use of volatile cues to prepare for herbivore attack. Since both constitutive and inducible plant volatile emissions can
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Many plant species are able to perceive mechanical stimuli and respond with physiological, morphological or biochemical adjustments. Such changes in plant status may be detected by herbivory insects providing them with reliable cues about... more
Many plant species are able to perceive mechanical stimuli and respond with physiological, morphological or biochemical adjustments. Such changes in plant status may be detected by herbivory insects providing them with reliable cues about host plant quality. The broader ecological significance of induced plant responses to mechanical stimuli on herbivore insect behavior has not been explicitly investigated. In this study examined whether plant response to 1 min daily touching treatment over a period of 6 days affects olfactory response and 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. Both tested aphid species showed significantly reduced acceptance of touched plants compared with untouched plants. Volatiles released by touched and untouched plants were collected and identified by gas chromatography-mass spectrometry (GC/MS). Stepwise discriminant analyses identified (E)-nerolidol and (E)-β-caryophyllene 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. Olfactory bioassay demonstrated aphid avoidance of volatiles emitted by touched plants. Our study suggests that even brief mechanical stimuli can induce changes in plants that have potential to affect host plant selection and acceptance by aphids. The link between plant response to mechanical stimuli and insect behaviour identified in our study represents a new phenomenon that contributes to the broader ecological significance of induced plant responses to mechanical stress.