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Monika Hilker - One of the best experts on this subject based on the ideXlab platform.
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phenotypic plasticity of mate recognition systems prevents sexual interference between two sympatric Leaf Beetle species
Evolution, 2016Co-Authors: Tobias Otte, Monika Hilker, Sven GeiselhardtAbstract:Maladaptive sexual interactions among heterospecific individuals (sexual interference) can prevent the coexistence of animal species. Thus, the avoidance of sexual interference by divergence of mate recognition systems is crucial for a stable coexistence in sympatry. Mate recognition systems are thought to be under tight genetic control. However, we demonstrate that mate recognition systems of two closely related sympatric Leaf Beetle species show a high level of host-induced phenotypic plasticity. Mate choice in the mustard Leaf Beetles, Phaedon cochleariae and P. armoraciae, is mediated by cuticular hydrocarbons (CHCs). Divergent host plant use causes a divergence of CHC phenotypes, whereas similar host use leads to their convergence. Consequently, both species exhibit significant behavioral isolation when they feed on alternative host species, but mate randomly when using a common host. Thus, sexual interference between these syntopic Leaf Beetles is prevented by host-induced phenotypic plasticity rather than by genotypic divergence of mate recognition systems.
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electrophysiological responses of the blue willow Leaf Beetle phratora vulgatissima to volatiles of different salix viminalis genotypes
Entomologia Experimentalis Et Applicata, 2007Co-Authors: Patricia Fernandez, Torsten Meiners, Christer Bjorkman, Monika HilkerAbstract:Among numerous other factors, host-plant volatiles may affect selection of food plants by herbivorous insects. The blue willow Leaf Beetle, Phratora vulgatissima (L.) (Coleoptera: Chrysomelidae), is known to differentiate between willow species and genotypes. However, so far no knowledge is available on the physiological abilities of this Leaf Beetle to respond to willow volatiles. In this study, we recorded electroantennograms of male and female P. vulgatissima to volatiles from two Salix viminalis L. (Salicaceae) genotypes: Jorr and 78021. The headspace of these genotypes were analysed by coupled gas chromatography-mass spectrometry. In addition to known green Leaf volatiles (GLV), several terpenoid components were found. Both males and females of P. vulgatissima showed strong responses to the GLVs (Z)-3-hexenol and (Z)-3-hexenyl acetate, and moderate responses to (E)-ocimene and β-caryophyllene. Females, but not males, also responded to R-(+)-limonene. This work represents a further step to identify substances relevant for the orientation of P. vulgatissima to host plants.
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host location in oomyzus gallerucae hymenoptera eulophidae an egg parasitoid of the elm Leaf Beetle xanthogaleruca luteola coleoptera chrysomelidae
Oecologia, 1997Co-Authors: Torsten Meiners, Monika HilkerAbstract:Eggs of the elm Leaf Beetle Xanthogaleruca luteola are often heavily attacked by the chalcidoid wasp Oomyzus gallerucae. We studied the chemical signals mediating interactions between the egg parasitoid, its host, and the plant Ulmus campestris. Olfactometer bioassays with O. gallerucae showed that volatiles of the host-plant complex attract the parasitoid. In order to determine the source of attractive volatiles within this host-plant-complex, we tested separately the effect of odours of eggs, gravid elm Leaf Beetle females, faeces of the Beetles and elm twigs (with undamaged leaves and leaves damaged either mechanically or by feeding of the Beetles). Odours of faeces of the elm Leaf Beetle were attractive, whereas neither volatiles from eggs nor from gravid females acted as attractants. Volatiles from undamaged or damaged plants did not elicit a positive reaction in O. gallerucae, whereas volatiles from feeding-damaged plants onto which host eggs had been deposited were attractive. This latter result suggests that it is not feeding but deposition of host eggs onto elm leaves that induces the production of plant volatiles attractive to the egg parasitoid. Investigations of the search patterns of O. gallerucae within the habitat by laboratory bioassays revealed that the egg parasitoid encounters host eggs by chance. Contact kairomones from faeces were demonstrated to be important in microhabitat acceptance, while contact kairomones isolated from the host eggs are relevant for host recognition.
Gaylord A. Desurmont - One of the best experts on this subject based on the ideXlab platform.
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seasonal decline in plant defence is associated with relaxed offensive oviposition behaviour in the viburnum Leaf Beetle pyrrhalta viburni
Ecological Entomology, 2014Co-Authors: Gaylord A. Desurmont, Ann E Hajek, Anurag AgrawalAbstract:1. Plant defence of Viburnum shrubs against oviposition by its specialist herbivore, the viburnum Leaf Beetle [VLB Pyrrhalta viburni(Paykull)], involves an egg-crushing wound response in twigs. Although the response is variable among Viburnum species, it can have a strong impact on egg survivorship. Beetles typically aggregate egg masses with conspecifics along infested twigs, forming clusters that can overwhelm the twig response. It was investigated whether twig responses and Beetle oviposition behaviour vary seasonally. 2. In a field experiment, twig defences decreased towards the end of the VLB oviposition period: wound response of the North American Viburnum dentatum L. and the European V. opulus L. was reduced by 100% and 54%, respectively, in September compared with the July to August period. 3. Oviposition trials demonstrated a corresponding behavioural change: VLB females displayed aggregative oviposition in August, but not in September. 4. Further tests revealed that late-season VLB females reverted to aggregative oviposition after being kept on uninfested twigs, whereas females kept on heavily infested twigs did not. This behavioural change suggests that relaxation of aggregative oviposition originates from cues associated with high densities of egg masses. 5. Relaxation of aggregative oviposition may be adaptive (and beneficial for invasion) on shrubs with low levels of defences by reducing intra-specific competition.
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oviposition strategy as a means of local adaptation to plant defence in native and invasive populations of the viburnum Leaf Beetle
Proceedings of The Royal Society B: Biological Sciences, 2012Co-Authors: Gaylord A. Desurmont, Franck Herard, Anurag AgrawalAbstract:Herbivores have been hypothesized to adapt locally to variation in plant defences and such adaptation could facilitate novel associations in the context of biological invasions. Here, we show that in the native range of the viburnum Leaf Beetle (VLB, Pyrrhalta viburni ), two populations of geographically isolated hosts— Viburnum opulus and Viburnum tinus—have divergent defences against VLB oviposition: negative versus positive density-dependent egg-crushing wound responses, respectively. Populations of Beetles coexisting with each host show an adaptive behavioural response: aggregative versus non-aggregative oviposition on V .o pulusand V. tinus, respectively. In parallel, we show that in North America, where VLB is invasive, defences of three novel hosts are negatively density-dependent, and Beetles’ oviposition behaviour is aggregative. Thus, local adaptation to plant defences has the potential to facilitate the invasion of herbivores onto novel hosts.
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predation by podisus maculiventris say hemiptera pentatomidae on viburnum Leaf Beetle pyrrhalta viburni paykull coleoptera chrysomelidae under laboratory and field conditions
Environmental Entomology, 2008Co-Authors: Gaylord A. Desurmont, Paul A. WestonAbstract:To evaluate the potential of Podisus maculiventris (Say) (Heteroptera: Pentatomidae) as a biological control agent against viburnum Leaf Beetle, Pyrrhalta viburni (Paykull) (Coleoptera: Chrysomelidae), laboratory trials were conducted to measure prey consumption of P. maculiventris over nymphal development. Field trials tested the impact of augmentative releases of P. maculiventris nymphs on populations of P. viburni, using both open shrubs and caged branches of Viburnum trilobum. In the laboratory,P.maculiventris nymphs successfully developed while preying onP.viburni larvae and adults. Each nymph consumed an average of 100.6 larvae or 16.9 adults. Immature development duration was comparable between nymphs feeding on P. viburni adults and those given Galleria mellonella (L.) (Lepidoptera: Pyralidae) larvae as prey. In Þeld trials, inundative releases of 30 P. maculiventris nymphs on naturally infested V. trilobum shrubs signiÞcantly reduced pest defoliation on shrubs infested with3,000 larvae but had no effect on shrubs with heavier infestations. On caged branches, individual nymphs successfully developed when feeding only onP. viburni larvae. These results show that P. viburni larvae and adults are suitable prey for P. maculiventris and this predator could potentially be developed as a biological control agent against P. viburni.
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influence of prey size and environmental factors on predation by podisus maculiventris hemiptera pentatomidae on viburnum Leaf Beetle coleoptera chrysomelidae
Canadian Entomologist, 2008Co-Authors: Gaylord A. Desurmont, Paul A. WestonAbstract:Experiments were conducted under laboratory conditions to determine the influence of the relative sizes of predator and prey, temperature, presence of refugia, size of the search area, and host-plant species on the predation performance of Podisus maculiventris (Say) nymphs against viburnum Leaf Beetle, Pyrrhalta viburni (Paykull), a new landscape pest in North America that feeds on the foliage of species of Viburnum L. (Caprifoliaceae). Predator handling time was positively correlated with body mass of the prey for all instars of P. maculiventris, but the rate of increase of handling time relative to prey mass decreased as predator age increased. Temperature was positively correlated with predation rates, but the presence of refugia did not have an impact on predation. The influence of host-plant species and size of the search area was tested on southern arrowwood (Viburnum dentatum L.) and American cranberrybush (Viburnum opulus L. var. americanum Aiton). There was a significant interaction between plan...
Torsten Meiners - One of the best experts on this subject based on the ideXlab platform.
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electrophysiological responses of the blue willow Leaf Beetle phratora vulgatissima to volatiles of different salix viminalis genotypes
Entomologia Experimentalis Et Applicata, 2007Co-Authors: Patricia Fernandez, Torsten Meiners, Christer Bjorkman, Monika HilkerAbstract:Among numerous other factors, host-plant volatiles may affect selection of food plants by herbivorous insects. The blue willow Leaf Beetle, Phratora vulgatissima (L.) (Coleoptera: Chrysomelidae), is known to differentiate between willow species and genotypes. However, so far no knowledge is available on the physiological abilities of this Leaf Beetle to respond to willow volatiles. In this study, we recorded electroantennograms of male and female P. vulgatissima to volatiles from two Salix viminalis L. (Salicaceae) genotypes: Jorr and 78021. The headspace of these genotypes were analysed by coupled gas chromatography-mass spectrometry. In addition to known green Leaf volatiles (GLV), several terpenoid components were found. Both males and females of P. vulgatissima showed strong responses to the GLVs (Z)-3-hexenol and (Z)-3-hexenyl acetate, and moderate responses to (E)-ocimene and β-caryophyllene. Females, but not males, also responded to R-(+)-limonene. This work represents a further step to identify substances relevant for the orientation of P. vulgatissima to host plants.
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host location in oomyzus gallerucae hymenoptera eulophidae an egg parasitoid of the elm Leaf Beetle xanthogaleruca luteola coleoptera chrysomelidae
Oecologia, 1997Co-Authors: Torsten Meiners, Monika HilkerAbstract:Eggs of the elm Leaf Beetle Xanthogaleruca luteola are often heavily attacked by the chalcidoid wasp Oomyzus gallerucae. We studied the chemical signals mediating interactions between the egg parasitoid, its host, and the plant Ulmus campestris. Olfactometer bioassays with O. gallerucae showed that volatiles of the host-plant complex attract the parasitoid. In order to determine the source of attractive volatiles within this host-plant-complex, we tested separately the effect of odours of eggs, gravid elm Leaf Beetle females, faeces of the Beetles and elm twigs (with undamaged leaves and leaves damaged either mechanically or by feeding of the Beetles). Odours of faeces of the elm Leaf Beetle were attractive, whereas neither volatiles from eggs nor from gravid females acted as attractants. Volatiles from undamaged or damaged plants did not elicit a positive reaction in O. gallerucae, whereas volatiles from feeding-damaged plants onto which host eggs had been deposited were attractive. This latter result suggests that it is not feeding but deposition of host eggs onto elm leaves that induces the production of plant volatiles attractive to the egg parasitoid. Investigations of the search patterns of O. gallerucae within the habitat by laboratory bioassays revealed that the egg parasitoid encounters host eggs by chance. Contact kairomones from faeces were demonstrated to be important in microhabitat acceptance, while contact kairomones isolated from the host eggs are relevant for host recognition.
Jonathan A Newman - One of the best experts on this subject based on the ideXlab platform.
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climate and host plant availability impact the future distribution of the bean Leaf Beetle cerotoma trifurcata
Global Change Biology, 2014Co-Authors: Emily A Berzitis, Jordan N Minigan, Rebecca H Hallett, Jonathan A NewmanAbstract:The bean Leaf Beetle, Cerotoma trifurcata, has become a major pest of soybean throughout its North American range. With a changing climate, there is the potential for this pest to further expand its distribution and become an increasingly severe pest in certain regions. To examine this possibility, we developed bioclimatic envelope models for both the bean Leaf Beetle, and its most important agronomic host plant, soybean (Glycine max). These two models were combined to examine the potential future pest status of the Beetle using climate change projections from multiple general circulation models (GCMs) and climate change scenarios. Despite the broad tolerances of soybean, incorporation of host plant availability substantially decreased the suitable and favourable areas for the bean Leaf Beetle as compared to an evaluation based solely on the climate envelope of the Beetle, demonstrating the importance of incorporating biotic interactions in these predictions. The use of multiple GCM-scenario combinations also revealed differences in predictions depending on the choice of GCM, with scenario choice having less of an impact. While the Norwegian model predicted little northward expansion of the Beetle from its current northern range limit of southern Ontario and overall decreases in suitable and favourable areas over time, the Canadian and Russian models predict that much of Ontario and Quebec will become suitable for the Beetle in the future, as well as Manitoba under the Russian model. The Russian model also predicts expansion of the suitable and favourable areas for the Beetle over time. Two predictions that do not depend on our choice of GCM include a decrease in suitability of the Mississippi Delta region and continued favourability of the southeastern United States.
Jan Christian Habel - One of the best experts on this subject based on the ideXlab platform.
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ecological separation versus geographical isolation population genetics of the water lily Leaf Beetle galerucella nymphaeae coleoptera chrysomelidae
Biological Journal of The Linnean Society, 2015Co-Authors: Robert Lechner, Ralph Kuehn, Thomas Schmitt, Jan Christian HabelAbstract:Many sedentary species with specific habitat demands occur in isolated populations and thus show strong intraspecific genetic differentiation, shaped either by geographical isolation or by local ecological adaptation to specific environmental conditions. The water-lily Leaf Beetle Galerucella nymphaeae has two ecotypes: one only found feeding as a specialist on just a few host plant species of the family Polygonaceae, and the other on various representatives of the family Nymphaeaceae as a generalist. To test whether the differentiation in ecotypes is also reflected in the population genetic structure, we combined amplified fragment length polymorhism data (> 500 polymorphic fragments; four sampling sites, 27–31 individuals each) with ex-situ feeding experiments (ten individuals from each site). We found that both ecotypes are genetically well differentiated. Furthermore, the genetic divergence between the two studied generalist Nymphaeaceae ecotype populations was also high. In contrast, the two specialist Polygonaceae ecotype populations clustered closely together (thus not depending on geographical isolation), indicating an ecology-driven genetic structuring. Our ex-situ reciprocal feeding experiment revealed that only individuals of the Polygonaceae ecotype are strictly dependent on their host plant family: individuals from populations feeding Polygonaceae are less likely to feed on species from the family Nymphaeaceae than the reverse. Our data show that host preference may drive genetic differentiation even more strongly than simple geographical distance.