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Christoph Vorburger - One of the best experts on this subject based on the ideXlab platform.
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prior adaptation of parasitoids improves biological control of symbiont protected pests
Evolutionary Applications, 2020Co-Authors: Christoph Vorburger, Silvan RossbacherAbstract:There is increasing demand for sustainable pest management to reduce harmful effects of pesticides on the environment and human health. For pest Aphids, biological control with parasitoid wasps provides a welcome alternative, particularly in greenhouses. However, Aphids are frequently infected with the heritable bacterial endosymbiont Hamiltonella defensa, which increases resistance to parasitoids and thereby hampers biological control. Using the Black Bean Aphid (Aphis fabae) and its main parasitoid Lysiphlebus fabarum, we tested whether prior adaptation of parasitoids can improve the control of symbiont-protected pests. We had parasitoid lines adapted to two different strains of H. defensa by experimental evolution, as well as parasitoids evolved on H. defensa-free Aphids. We compared their ability to control caged Aphid populations comprising 60% unprotected and 40% H. defensa-protected Aphids, with both H. defensa strains present in the populations. Parasitoids that were not adapted to H. defensa had virtually no effect on Aphid population dynamics compared to parasitoid-free controls, but one of the adapted lines and a mixture of both adapted lines controlled Aphids successfully, strongly benefitting plant growth. Selection by parasitoids altered Aphid population composition in a very specific manner. Aphid populations became dominated by H. defensa-protected Aphids in the presence of parasitoids, and each adapted parasitoid line selected for the H. defensa strain it was not adapted to. This study shows, for the first time, that prior adaptation of parasitoids improves biological control of symbiont-protected pests, but the high specificity of parasitoid counter-resistance may represent a challenge for its implementation.
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Faithful vertical transmission but ineffective horizontal transmission of bacterial endosymbionts during sexual reproduction of the Black Bean Aphid, Aphis fabae
Ecological Entomology, 2017Co-Authors: Christoph Vorburger, Gabrielle Siegrist, Nicola RhynerAbstract:1. Insects are commonly infected with bacterial endosymbionts. In addition to the costs and benefits associated with harbouring these symbionts, their rates of vertical and horizontal transmission are important determinants of symbiont prevalence. 2. Aphids are cyclical parthenogens and show virtually perfect maternal transmission of endosymbionts during asexual reproduction. Less clear is the role of the annual sexual generation, during which overwintering eggs are produced. Data from pea Aphids (Acyrthosiphon pisum Harris) suggest that maternal transmission failures and horizontal transmission via males may occur under sexual reproduction at least occasionally. No such data exist for other Aphid species. 3. In the present study, the rates of maternal and paternal transmission of facultative endosymbionts during sexual reproduction in the Black Bean Aphid, Aphis fabae (Scopoli) were examined. Crosses were performed between clones infected with Hamiltonella defensa, clones infected with Regiella insecticola and clones without facultative endosymbionts, and eggs were overwintered under three different conditions. 4. Only one of 205 offspring from crosses testing for maternal transmission failed to inherit the symbiont present in the maternal clone, and in crosses testing for horizontal transmission, only one of 412 offspring acquired a facultative symbiont from the father. 5. These results show that in A. fabae, maternal transmission of H. defensa and R. insecticola is extremely reliable also during sexual reproduction, indicating that maternal transmission failures are unlikely to exert a significant influence on frequencies of infection in the field. Paternal transmission of endosymbionts was exceedingly rare, suggesting that this route of horizontal transmission may be less important than hitherto assumed.
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symbiont conferred protection against hymenopteran parasitoids in Aphids how general is it
Ecological Entomology, 2015Co-Authors: Christoph Vorburger, Luis CayetanoAbstract:1. Hosts are often targeted by multiple species of parasites, leading to a confluence of selective pressures on them. In response, hosts may either evolve defences that act very generally, or specific defences against particular parasites. Aphids are attacked by multiple species of endoparasitoid wasps, and there is clear evidence that heritable endosymbionts can confer resistance against some of these wasps. Less clear is how symbiont-conferred resistance in a single host acts against multiple parasitoid species. 2. This question was addressed in the Black Bean Aphid, Aphis fabae (Scopoli). Unprotected Aphids and Aphids protected by three different strains of the defensive endosymbiont Hamiltonella defensa were exposed to four species of parasitic wasps: the parthenogenetic species Lysiphlebus fabarum (Marshall), which was represented by three different asexual lines, and the sexual species Aphidius colemani (Viereck), Binodoxys angelicae (Halliday), and Aphelinus chaonia (Walker). 3. Hamiltonella defensa provided strong protection against L. fabarum and Aphidius colemani, but there was no evidence that H. defensa-infected Aphids were more resistant to the other parasitoid species. While Aphidius colemani was virtually unable to parasitise any Aphids harbouring H. defensa, there was variation among the three asexual lines of L. fabarum in how susceptible they were to the defence provided by the different symbiont strains, resulting in a significant genotype-by-genotype interaction. 4. The present results suggest that symbiosis with H. defensa does not provide Aphids with a general defence against parasitoid wasps, possibly because some species have evolved specific counter adaptations or because biological differences preclude the symbiont's effectiveness against these species.
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climate effects on life cycle variation and population genetic architecture of the Black Bean Aphid aphis fabae
Molecular Ecology, 2011Co-Authors: Christoph Sandrock, Christoph Vorburger, Jabraeil RazmjouAbstract:Aphid species may exhibit different reproductive modes ranging from cyclical to obligate parthenogenesis. The distribution of life cycle variation in Aphids is generally determined by ecological forces, mainly climate, because only sexually produced diapausing eggs can survive harsh winters or periods of absence of suitable host plants. Aphids are thus interesting models to investigate intrinsic and environmental factors shaping the competition among sexual and asexual lineages. We conducted a Europe-wide sampling of Black Bean Aphids, Aphis fabae, and combined population genetic analyses based on microsatellite data with an experimental determination of life cycle strategies. Aphids were collected from broad Beans (Vicia faba) as well as some Chenopodiaceae, but we detected no genetic differentiation between Aphids from different host plants. Consistent with model predictions, life cycle variation was related to climate, with Aphids from areas with cold winters investing more in sexual reproduction than Aphids from areas with mild winters. Accordingly, only populations from mild areas exhibited a clear genetic signature of clonal reproduction. These differences arise despite substantial gene flow over large distances, which was evident from a very low geographic population structure and a lack of isolation-by-distance among 18 sites across distances of more than 1000 km. There was virtually no genetic differentiation between Aphids with different reproductive modes, suggesting that new asexual lineages are formed continuously. Indeed, a surprising number of A. fabae genotypes even from colder climates produced some parthenogenetic offspring under simulated winter conditions. From this we predict that a shift to predominantly asexual reproduction could take place rapidly under climate warming.
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host genotype affects the relative success of competing lines of Aphid parasitoids under superparasitism
Ecological Entomology, 2010Co-Authors: Christoph Vorburger, Bettina Eugster, Jorg Villiger, Corinne WimmerAbstract:1. In solitary parasitoids, only one individual can complete development in a given host. Therefore, solitary parasitoids tend to prefer unparasitised hosts for oviposition, yet under high parasitoid densities, superparasitism is frequent and results in fierce competition for the host's limited resources. This may lead to selection for the best intra-host competitors. 2. Increased intra-host competitive ability may evolve under a high risk of superparasitism if this trait exhibits genetic variation, and if competitive differences among parasitoid genotypes are consistent across environments, e.g. different host genotypes. 3. These assumptions were addressed in the Aphid parasitoid Lysiphlebus fabarum (Hymenoptera: Braconidae: Aphidiinae) and its main host, the Black Bean Aphid, Aphis fabae (Scopoli) (Hemiptera: Aphididae). Three parthenogenetic lines of L. fabarum were allowed to parasitise three Aphid clones singly and in all pairwise combinations (superparasitism). The winning parasitoid in superparasitised Aphids was determined by microsatellite analysis. 4. The proportions of singly parasitised Aphids that were mummified were similar for the three parasitoid lines and did not differ significantly among host clones. 5. Under superparasitism, significant biases in favour of one parasitoid line were observed for some combinations, indicating that there is genetic variation for intra-host competitive ability. However, the outcome of superparasitism was inconsistent across Aphid clones and thus influenced significantly by the host clone in which parasitoids competed. 6. Overall, this study shows that the fitness of Aphid parasitoids under superparasitism is determined by complex interactions with competitors as well as hosts, possibly hampering the evolution of improved intra-host competitive ability.
Jim Hardie - One of the best experts on this subject based on the ideXlab platform.
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volatiles functioning as host cues in a blend become nonhost cues when presented alone to the Black Bean Aphid
Animal Behaviour, 2010Co-Authors: Ben Webster, J. A. Pickett, Toby J. A. Bruce, Jim HardieAbstract:Herbivorous insects recognize and locate their hosts by detecting characteristic blends of volatile compounds these plants emit. The possibility that insects may use the same compounds in a different context as nonhost cues has received relatively little attention. Volatiles normally emitted by the host but encountered without other host volatiles could theoretically function as nonhost cues. We hypothesized that insects might show a positive response to host volatile compounds when encountered together in a blend but avoid the same volatiles when encountered individually. To test this we examined the behavioural responses of the Black Bean Aphid, Aphis fabae, to physiologically relevant doses of volatile compounds emitted by its host, Vicia faba, which had been previously implicated in host recognition. Of 15 volatiles tested for behavioural activity, 10 caused Aphids to respond negatively, suggesting they were repellent. We then made a blend comprising each of these compounds at the concentration at which they elicited the most negative behavioural response. The resultant blend elicited a positive response, suggesting it was attractive/arrestant. This demonstrated that the same volatile compounds can function as both host and nonhost cues, depending upon the context in which they are perceived. Thus, background odour context needs to be considered for successful use of behaviourally active volatile compounds in integrated pest management strategies. Furthermore, the finding that odorants are perceived differently when combined suggests that there is an emergent property of odour perception whereby discrimination of odour quality can occur according to blend properties.
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between plant and diurnal variation in quantities and ratios of volatile compounds emitted by vicia faba plants
Phytochemistry, 2010Co-Authors: Ben Webster, Jim Hardie, Toby J. A. Bruce, Salvador A. Gezan, J. A. PickettAbstract:Ratios of volatile phytochemicals potentially offer a means for insects to recognise their host-plant species. However, for this to occur ratios of volatiles would need to be sufficiently consistent between plants and over time to constitute a host-characteristic cue. In this context we collected headspace samples from Vicia faba plants to determine how consistent ratios of key volatile phytochemicals used in host location by one of its insect pests, the Black Bean Aphid, Aphis fabae, were. These were (E)-2-hexenal, (Z)-3-hexen-1-ol, 1-hexanol, benzaldehyde, 6-methyl-5-hepten-2-one, octanal, (Z)-3-hexen-1-yl acetate, (R)-linalool, methyl salicylate, decanal, undecanal, (E)-caryophyllene, (E)-β-farnesene, (S)-germacrene D, and (E, E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, which had previously been found to be electrophysiologically and behaviourally active to A. fabae. Although the quantities of volatiles produced by V. faba showed large between plant and diurnal variation, correlations between quantities of compounds indicated that the ratios of certain pairs of volatiles were very consistent. This suggests that there is a host-characteristic cue available to A. fabae in the form of ratios of volatiles.
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Between plant and diurnal variation in quantities and ratios of volatile compounds emitted by Vicia faba plants.
Phytochemistry, 2009Co-Authors: Ben Webster, Jim Hardie, Toby J. A. Bruce, Salvador A. Gezan, John A. PickettAbstract:Ratios of volatile phytochemicals potentially offer a means for insects to recognise their host-plant species. However, for this to occur ratios of volatiles would need to be sufficiently consistent between plants and over time to constitute a host-characteristic cue. In this context we collected headspace samples from Vicia faba plants to determine how consistent ratios of key volatile phytochemicals used in host location by one of its insect pests, the Black Bean Aphid, Aphis fabae, were. These were (E)-2-hexenal, (Z)-3-hexen-1-ol, 1-hexanol, benzaldehyde, 6-methyl-5-hepten-2-one, octanal, (Z)-3-hexen-1-yl acetate, (R)-linalool, methyl salicylate, decanal, undecanal, (E)-caryophyllene, (E)-beta-farnesene, (S)-germacrene D, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, which had previously been found to be electrophysiologically and behaviourally active to A. fabae. Although the quantities of volatiles produced by V. faba showed large between plant and diurnal variation, correlations between quantities of compounds indicated that the ratios of certain pairs of volatiles were very consistent. This suggests that there is a host-characteristic cue available to A. fabae in the form of ratios of volatiles.
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olfactory recognition of host plants in the absence of host specific volatile compounds host location in the Black Bean Aphid aphis fabae
Communicative & Integrative Biology, 2008Co-Authors: Ben Webster, J. A. Pickett, Toby J. A. Bruce, Jim HardieAbstract:The Black Bean Aphid, Aphis fabae, responds behaviorally to the odor of its host plant faba Bean (Vicia faba) in olfactometer bioassays by spending more time in the treated than control regions. We have shown previously that a blend of fifteen volatile compounds emitted by V. faba elicits the same response as a headspace sample of an intact V. faba plant. Here we report that no single compound within this blend fully accounts for the behavioral response and that the responses to individual compounds are different when in the context of the blend. As none of the compounds are specific to the host, we have hypothesized that A. fabae responds preferentially to the blend of compounds when presented in a species-specific combination of volatiles or in ratios specific to V. faba. Future plans to test which of these two hypotheses pertain to host-seeking Aphis fabae are discussed.
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identification of volatile compounds used in host location by the Black Bean Aphid aphis fabae
Journal of Chemical Ecology, 2008Co-Authors: Ben Webster, Samuel Dufour, Claudia Birkemeyer, Jim Hardie, Michael Alexander Birkett, Toby J. A. Bruce, J. A. PickettAbstract:Behavioral and electrophysiological responses of winged Aphis fabae to volatiles of faba Bean, Vicia faba (var. Sutton dwarf), plants were studied and semiochemicals used in host location were identified. In olfactometer bioassays, Aphids spent significantly more time in the region of the olfactometer where V. faba volatiles from an intact plant were present than in control regions with clean air. This response also occurred when an air entrainment sample of a V. faba plant was used as the odor source. Coupled gas chromatography–electroantennography revealed the presence of 16 electrophysiologically active compounds in the air entrainment sample. Fifteen of these were identified as (Z)-3-hexen-1-ol, 1-hexanol, (E)-2-hexenal, benzaldehyde, 6-methyl-5-hepten-2-one, octanal, (Z)-3-hexen-1-yl acetate, (R)-(−)-linalool, methyl salicylate, decanal, undecanal, (E)-caryophyllene, (E)-β-farnesene, (S)-(−)-germacrene D, and (E,E,)-4,8,12-trimethyl-1,3,7,11-tridecatetraene. An olfactometer response was observed to a 15-component synthetic blend that comprised all identified compounds at the same concentration and ratio as in the natural sample, with the Aphids spending significantly more time in the treated regions of the olfactometer where volatiles were present than in the control regions. These data are discussed in the context of insect host location and crop protection.
J. A. Pickett - One of the best experts on this subject based on the ideXlab platform.
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volatiles functioning as host cues in a blend become nonhost cues when presented alone to the Black Bean Aphid
Animal Behaviour, 2010Co-Authors: Ben Webster, J. A. Pickett, Toby J. A. Bruce, Jim HardieAbstract:Herbivorous insects recognize and locate their hosts by detecting characteristic blends of volatile compounds these plants emit. The possibility that insects may use the same compounds in a different context as nonhost cues has received relatively little attention. Volatiles normally emitted by the host but encountered without other host volatiles could theoretically function as nonhost cues. We hypothesized that insects might show a positive response to host volatile compounds when encountered together in a blend but avoid the same volatiles when encountered individually. To test this we examined the behavioural responses of the Black Bean Aphid, Aphis fabae, to physiologically relevant doses of volatile compounds emitted by its host, Vicia faba, which had been previously implicated in host recognition. Of 15 volatiles tested for behavioural activity, 10 caused Aphids to respond negatively, suggesting they were repellent. We then made a blend comprising each of these compounds at the concentration at which they elicited the most negative behavioural response. The resultant blend elicited a positive response, suggesting it was attractive/arrestant. This demonstrated that the same volatile compounds can function as both host and nonhost cues, depending upon the context in which they are perceived. Thus, background odour context needs to be considered for successful use of behaviourally active volatile compounds in integrated pest management strategies. Furthermore, the finding that odorants are perceived differently when combined suggests that there is an emergent property of odour perception whereby discrimination of odour quality can occur according to blend properties.
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between plant and diurnal variation in quantities and ratios of volatile compounds emitted by vicia faba plants
Phytochemistry, 2010Co-Authors: Ben Webster, Jim Hardie, Toby J. A. Bruce, Salvador A. Gezan, J. A. PickettAbstract:Ratios of volatile phytochemicals potentially offer a means for insects to recognise their host-plant species. However, for this to occur ratios of volatiles would need to be sufficiently consistent between plants and over time to constitute a host-characteristic cue. In this context we collected headspace samples from Vicia faba plants to determine how consistent ratios of key volatile phytochemicals used in host location by one of its insect pests, the Black Bean Aphid, Aphis fabae, were. These were (E)-2-hexenal, (Z)-3-hexen-1-ol, 1-hexanol, benzaldehyde, 6-methyl-5-hepten-2-one, octanal, (Z)-3-hexen-1-yl acetate, (R)-linalool, methyl salicylate, decanal, undecanal, (E)-caryophyllene, (E)-β-farnesene, (S)-germacrene D, and (E, E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, which had previously been found to be electrophysiologically and behaviourally active to A. fabae. Although the quantities of volatiles produced by V. faba showed large between plant and diurnal variation, correlations between quantities of compounds indicated that the ratios of certain pairs of volatiles were very consistent. This suggests that there is a host-characteristic cue available to A. fabae in the form of ratios of volatiles.
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olfactory recognition of host plants in the absence of host specific volatile compounds host location in the Black Bean Aphid aphis fabae
Communicative & Integrative Biology, 2008Co-Authors: Ben Webster, J. A. Pickett, Toby J. A. Bruce, Jim HardieAbstract:The Black Bean Aphid, Aphis fabae, responds behaviorally to the odor of its host plant faba Bean (Vicia faba) in olfactometer bioassays by spending more time in the treated than control regions. We have shown previously that a blend of fifteen volatile compounds emitted by V. faba elicits the same response as a headspace sample of an intact V. faba plant. Here we report that no single compound within this blend fully accounts for the behavioral response and that the responses to individual compounds are different when in the context of the blend. As none of the compounds are specific to the host, we have hypothesized that A. fabae responds preferentially to the blend of compounds when presented in a species-specific combination of volatiles or in ratios specific to V. faba. Future plans to test which of these two hypotheses pertain to host-seeking Aphis fabae are discussed.
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identification of volatile compounds used in host location by the Black Bean Aphid aphis fabae
Journal of Chemical Ecology, 2008Co-Authors: Ben Webster, Samuel Dufour, Claudia Birkemeyer, Jim Hardie, Michael Alexander Birkett, Toby J. A. Bruce, J. A. PickettAbstract:Behavioral and electrophysiological responses of winged Aphis fabae to volatiles of faba Bean, Vicia faba (var. Sutton dwarf), plants were studied and semiochemicals used in host location were identified. In olfactometer bioassays, Aphids spent significantly more time in the region of the olfactometer where V. faba volatiles from an intact plant were present than in control regions with clean air. This response also occurred when an air entrainment sample of a V. faba plant was used as the odor source. Coupled gas chromatography–electroantennography revealed the presence of 16 electrophysiologically active compounds in the air entrainment sample. Fifteen of these were identified as (Z)-3-hexen-1-ol, 1-hexanol, (E)-2-hexenal, benzaldehyde, 6-methyl-5-hepten-2-one, octanal, (Z)-3-hexen-1-yl acetate, (R)-(−)-linalool, methyl salicylate, decanal, undecanal, (E)-caryophyllene, (E)-β-farnesene, (S)-(−)-germacrene D, and (E,E,)-4,8,12-trimethyl-1,3,7,11-tridecatetraene. An olfactometer response was observed to a 15-component synthetic blend that comprised all identified compounds at the same concentration and ratio as in the natural sample, with the Aphids spending significantly more time in the treated regions of the olfactometer where volatiles were present than in the control regions. These data are discussed in the context of insect host location and crop protection.
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methyl salicylate and 1r 5s myrtenal are plant derived repellents for Black Bean Aphid aphis fabae scop homoptera Aphididae
Journal of Chemical Ecology, 1994Co-Authors: Jim Hardie, Lester J. Wadhams, J. A. Pickett, Rufus I Isaacs, C M WoodcockAbstract:Methyl salicylate and (−)-(1R,5S)-myrtenal stimulate specific olfactory cells in the primary rhinaria on the sixth and fifth antennal segments, respectively, of the Black Bean Aphid.Aphis fabae. In behavioral studies employing a linear track olfactometer, both compounds were repellent toA. fabae and also inhibited attraction to volatiles from its host, broad Bean (Vicia faba). Methyl salicylate is associated with secondary metabolite-based defense in plants, and the monoterpenoid (−)-(1R,5S)-myrtenal is metabolically related to (−)-(1S,5S)-α-pinene, an abundant component of defensive resins produced by gymnosperms. It is argued that these two compounds are employed byA. fabae as indicators of nutritionally unsuitable or nonhost plants.
Ben Webster - One of the best experts on this subject based on the ideXlab platform.
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volatiles functioning as host cues in a blend become nonhost cues when presented alone to the Black Bean Aphid
Animal Behaviour, 2010Co-Authors: Ben Webster, J. A. Pickett, Toby J. A. Bruce, Jim HardieAbstract:Herbivorous insects recognize and locate their hosts by detecting characteristic blends of volatile compounds these plants emit. The possibility that insects may use the same compounds in a different context as nonhost cues has received relatively little attention. Volatiles normally emitted by the host but encountered without other host volatiles could theoretically function as nonhost cues. We hypothesized that insects might show a positive response to host volatile compounds when encountered together in a blend but avoid the same volatiles when encountered individually. To test this we examined the behavioural responses of the Black Bean Aphid, Aphis fabae, to physiologically relevant doses of volatile compounds emitted by its host, Vicia faba, which had been previously implicated in host recognition. Of 15 volatiles tested for behavioural activity, 10 caused Aphids to respond negatively, suggesting they were repellent. We then made a blend comprising each of these compounds at the concentration at which they elicited the most negative behavioural response. The resultant blend elicited a positive response, suggesting it was attractive/arrestant. This demonstrated that the same volatile compounds can function as both host and nonhost cues, depending upon the context in which they are perceived. Thus, background odour context needs to be considered for successful use of behaviourally active volatile compounds in integrated pest management strategies. Furthermore, the finding that odorants are perceived differently when combined suggests that there is an emergent property of odour perception whereby discrimination of odour quality can occur according to blend properties.
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between plant and diurnal variation in quantities and ratios of volatile compounds emitted by vicia faba plants
Phytochemistry, 2010Co-Authors: Ben Webster, Jim Hardie, Toby J. A. Bruce, Salvador A. Gezan, J. A. PickettAbstract:Ratios of volatile phytochemicals potentially offer a means for insects to recognise their host-plant species. However, for this to occur ratios of volatiles would need to be sufficiently consistent between plants and over time to constitute a host-characteristic cue. In this context we collected headspace samples from Vicia faba plants to determine how consistent ratios of key volatile phytochemicals used in host location by one of its insect pests, the Black Bean Aphid, Aphis fabae, were. These were (E)-2-hexenal, (Z)-3-hexen-1-ol, 1-hexanol, benzaldehyde, 6-methyl-5-hepten-2-one, octanal, (Z)-3-hexen-1-yl acetate, (R)-linalool, methyl salicylate, decanal, undecanal, (E)-caryophyllene, (E)-β-farnesene, (S)-germacrene D, and (E, E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, which had previously been found to be electrophysiologically and behaviourally active to A. fabae. Although the quantities of volatiles produced by V. faba showed large between plant and diurnal variation, correlations between quantities of compounds indicated that the ratios of certain pairs of volatiles were very consistent. This suggests that there is a host-characteristic cue available to A. fabae in the form of ratios of volatiles.
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Between plant and diurnal variation in quantities and ratios of volatile compounds emitted by Vicia faba plants.
Phytochemistry, 2009Co-Authors: Ben Webster, Jim Hardie, Toby J. A. Bruce, Salvador A. Gezan, John A. PickettAbstract:Ratios of volatile phytochemicals potentially offer a means for insects to recognise their host-plant species. However, for this to occur ratios of volatiles would need to be sufficiently consistent between plants and over time to constitute a host-characteristic cue. In this context we collected headspace samples from Vicia faba plants to determine how consistent ratios of key volatile phytochemicals used in host location by one of its insect pests, the Black Bean Aphid, Aphis fabae, were. These were (E)-2-hexenal, (Z)-3-hexen-1-ol, 1-hexanol, benzaldehyde, 6-methyl-5-hepten-2-one, octanal, (Z)-3-hexen-1-yl acetate, (R)-linalool, methyl salicylate, decanal, undecanal, (E)-caryophyllene, (E)-beta-farnesene, (S)-germacrene D, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, which had previously been found to be electrophysiologically and behaviourally active to A. fabae. Although the quantities of volatiles produced by V. faba showed large between plant and diurnal variation, correlations between quantities of compounds indicated that the ratios of certain pairs of volatiles were very consistent. This suggests that there is a host-characteristic cue available to A. fabae in the form of ratios of volatiles.
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olfactory recognition of host plants in the absence of host specific volatile compounds host location in the Black Bean Aphid aphis fabae
Communicative & Integrative Biology, 2008Co-Authors: Ben Webster, J. A. Pickett, Toby J. A. Bruce, Jim HardieAbstract:The Black Bean Aphid, Aphis fabae, responds behaviorally to the odor of its host plant faba Bean (Vicia faba) in olfactometer bioassays by spending more time in the treated than control regions. We have shown previously that a blend of fifteen volatile compounds emitted by V. faba elicits the same response as a headspace sample of an intact V. faba plant. Here we report that no single compound within this blend fully accounts for the behavioral response and that the responses to individual compounds are different when in the context of the blend. As none of the compounds are specific to the host, we have hypothesized that A. fabae responds preferentially to the blend of compounds when presented in a species-specific combination of volatiles or in ratios specific to V. faba. Future plans to test which of these two hypotheses pertain to host-seeking Aphis fabae are discussed.
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identification of volatile compounds used in host location by the Black Bean Aphid aphis fabae
Journal of Chemical Ecology, 2008Co-Authors: Ben Webster, Samuel Dufour, Claudia Birkemeyer, Jim Hardie, Michael Alexander Birkett, Toby J. A. Bruce, J. A. PickettAbstract:Behavioral and electrophysiological responses of winged Aphis fabae to volatiles of faba Bean, Vicia faba (var. Sutton dwarf), plants were studied and semiochemicals used in host location were identified. In olfactometer bioassays, Aphids spent significantly more time in the region of the olfactometer where V. faba volatiles from an intact plant were present than in control regions with clean air. This response also occurred when an air entrainment sample of a V. faba plant was used as the odor source. Coupled gas chromatography–electroantennography revealed the presence of 16 electrophysiologically active compounds in the air entrainment sample. Fifteen of these were identified as (Z)-3-hexen-1-ol, 1-hexanol, (E)-2-hexenal, benzaldehyde, 6-methyl-5-hepten-2-one, octanal, (Z)-3-hexen-1-yl acetate, (R)-(−)-linalool, methyl salicylate, decanal, undecanal, (E)-caryophyllene, (E)-β-farnesene, (S)-(−)-germacrene D, and (E,E,)-4,8,12-trimethyl-1,3,7,11-tridecatetraene. An olfactometer response was observed to a 15-component synthetic blend that comprised all identified compounds at the same concentration and ratio as in the natural sample, with the Aphids spending significantly more time in the treated regions of the olfactometer where volatiles were present than in the control regions. These data are discussed in the context of insect host location and crop protection.
Toby J. A. Bruce - One of the best experts on this subject based on the ideXlab platform.
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volatiles functioning as host cues in a blend become nonhost cues when presented alone to the Black Bean Aphid
Animal Behaviour, 2010Co-Authors: Ben Webster, J. A. Pickett, Toby J. A. Bruce, Jim HardieAbstract:Herbivorous insects recognize and locate their hosts by detecting characteristic blends of volatile compounds these plants emit. The possibility that insects may use the same compounds in a different context as nonhost cues has received relatively little attention. Volatiles normally emitted by the host but encountered without other host volatiles could theoretically function as nonhost cues. We hypothesized that insects might show a positive response to host volatile compounds when encountered together in a blend but avoid the same volatiles when encountered individually. To test this we examined the behavioural responses of the Black Bean Aphid, Aphis fabae, to physiologically relevant doses of volatile compounds emitted by its host, Vicia faba, which had been previously implicated in host recognition. Of 15 volatiles tested for behavioural activity, 10 caused Aphids to respond negatively, suggesting they were repellent. We then made a blend comprising each of these compounds at the concentration at which they elicited the most negative behavioural response. The resultant blend elicited a positive response, suggesting it was attractive/arrestant. This demonstrated that the same volatile compounds can function as both host and nonhost cues, depending upon the context in which they are perceived. Thus, background odour context needs to be considered for successful use of behaviourally active volatile compounds in integrated pest management strategies. Furthermore, the finding that odorants are perceived differently when combined suggests that there is an emergent property of odour perception whereby discrimination of odour quality can occur according to blend properties.
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between plant and diurnal variation in quantities and ratios of volatile compounds emitted by vicia faba plants
Phytochemistry, 2010Co-Authors: Ben Webster, Jim Hardie, Toby J. A. Bruce, Salvador A. Gezan, J. A. PickettAbstract:Ratios of volatile phytochemicals potentially offer a means for insects to recognise their host-plant species. However, for this to occur ratios of volatiles would need to be sufficiently consistent between plants and over time to constitute a host-characteristic cue. In this context we collected headspace samples from Vicia faba plants to determine how consistent ratios of key volatile phytochemicals used in host location by one of its insect pests, the Black Bean Aphid, Aphis fabae, were. These were (E)-2-hexenal, (Z)-3-hexen-1-ol, 1-hexanol, benzaldehyde, 6-methyl-5-hepten-2-one, octanal, (Z)-3-hexen-1-yl acetate, (R)-linalool, methyl salicylate, decanal, undecanal, (E)-caryophyllene, (E)-β-farnesene, (S)-germacrene D, and (E, E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, which had previously been found to be electrophysiologically and behaviourally active to A. fabae. Although the quantities of volatiles produced by V. faba showed large between plant and diurnal variation, correlations between quantities of compounds indicated that the ratios of certain pairs of volatiles were very consistent. This suggests that there is a host-characteristic cue available to A. fabae in the form of ratios of volatiles.
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Between plant and diurnal variation in quantities and ratios of volatile compounds emitted by Vicia faba plants.
Phytochemistry, 2009Co-Authors: Ben Webster, Jim Hardie, Toby J. A. Bruce, Salvador A. Gezan, John A. PickettAbstract:Ratios of volatile phytochemicals potentially offer a means for insects to recognise their host-plant species. However, for this to occur ratios of volatiles would need to be sufficiently consistent between plants and over time to constitute a host-characteristic cue. In this context we collected headspace samples from Vicia faba plants to determine how consistent ratios of key volatile phytochemicals used in host location by one of its insect pests, the Black Bean Aphid, Aphis fabae, were. These were (E)-2-hexenal, (Z)-3-hexen-1-ol, 1-hexanol, benzaldehyde, 6-methyl-5-hepten-2-one, octanal, (Z)-3-hexen-1-yl acetate, (R)-linalool, methyl salicylate, decanal, undecanal, (E)-caryophyllene, (E)-beta-farnesene, (S)-germacrene D, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, which had previously been found to be electrophysiologically and behaviourally active to A. fabae. Although the quantities of volatiles produced by V. faba showed large between plant and diurnal variation, correlations between quantities of compounds indicated that the ratios of certain pairs of volatiles were very consistent. This suggests that there is a host-characteristic cue available to A. fabae in the form of ratios of volatiles.
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olfactory recognition of host plants in the absence of host specific volatile compounds host location in the Black Bean Aphid aphis fabae
Communicative & Integrative Biology, 2008Co-Authors: Ben Webster, J. A. Pickett, Toby J. A. Bruce, Jim HardieAbstract:The Black Bean Aphid, Aphis fabae, responds behaviorally to the odor of its host plant faba Bean (Vicia faba) in olfactometer bioassays by spending more time in the treated than control regions. We have shown previously that a blend of fifteen volatile compounds emitted by V. faba elicits the same response as a headspace sample of an intact V. faba plant. Here we report that no single compound within this blend fully accounts for the behavioral response and that the responses to individual compounds are different when in the context of the blend. As none of the compounds are specific to the host, we have hypothesized that A. fabae responds preferentially to the blend of compounds when presented in a species-specific combination of volatiles or in ratios specific to V. faba. Future plans to test which of these two hypotheses pertain to host-seeking Aphis fabae are discussed.
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identification of volatile compounds used in host location by the Black Bean Aphid aphis fabae
Journal of Chemical Ecology, 2008Co-Authors: Ben Webster, Samuel Dufour, Claudia Birkemeyer, Jim Hardie, Michael Alexander Birkett, Toby J. A. Bruce, J. A. PickettAbstract:Behavioral and electrophysiological responses of winged Aphis fabae to volatiles of faba Bean, Vicia faba (var. Sutton dwarf), plants were studied and semiochemicals used in host location were identified. In olfactometer bioassays, Aphids spent significantly more time in the region of the olfactometer where V. faba volatiles from an intact plant were present than in control regions with clean air. This response also occurred when an air entrainment sample of a V. faba plant was used as the odor source. Coupled gas chromatography–electroantennography revealed the presence of 16 electrophysiologically active compounds in the air entrainment sample. Fifteen of these were identified as (Z)-3-hexen-1-ol, 1-hexanol, (E)-2-hexenal, benzaldehyde, 6-methyl-5-hepten-2-one, octanal, (Z)-3-hexen-1-yl acetate, (R)-(−)-linalool, methyl salicylate, decanal, undecanal, (E)-caryophyllene, (E)-β-farnesene, (S)-(−)-germacrene D, and (E,E,)-4,8,12-trimethyl-1,3,7,11-tridecatetraene. An olfactometer response was observed to a 15-component synthetic blend that comprised all identified compounds at the same concentration and ratio as in the natural sample, with the Aphids spending significantly more time in the treated regions of the olfactometer where volatiles were present than in the control regions. These data are discussed in the context of insect host location and crop protection.