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Hermann M Niemeyer - One of the best experts on this subject based on the ideXlab platform.
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Non-host volatiles do not affect host acceptance by alate virginoparae of Rhopalosiphum padi (Hemiptera: Aphididae) settled on the host plant surface
European Journal of Entomology, 2005Co-Authors: Ruby Olivares-donoso, Hermann M NiemeyerAbstract:Using electrical penetration graphs to monitor aphid feeding, it was shown that volatiles of a non-host plant (alfalfa, Medicago sativa L.) did not disrupt the process of host acceptance by alate virginoparae of the birdcherry-oat aphid, Rhopalosiphum padi L., once it was settled on a host plant (wheat, Triticum aestivum L.).
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olfactometer assessed responses of aphid Rhopalosiphum padi to wheat and oat volatiles
Journal of Chemical Ecology, 1998Co-Authors: Andres Quiroz, Hermann M NiemeyerAbstract:Volatiles from wheat and oat seedlings elicited attraction in apterae and alatae Rhopalosiphum padi. Cereal volatiles were identified by GC-MS and olfactometric tests were performed with each compound. Attraction of aphids was elicited by (E)-2-hexenyl acetate, (Z)-3-hexenol, (E)-2-hexenyl acetate, (E)-2-hexenol, (Z)-2-hexenol, n-heptanal, n-octanal, n-nonanal, n-decanal, benzaldehyde, and linalool. The difference between the sensory capacity of alatae and apterae is discussed in relation to migrations between hosts during their life cycle.
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Olfactometer-assessed responses of aphid Rhopalosiphum padi to wheat and oat volatiles
Journal of Chemical Ecology, 1998Co-Authors: Andres Quiroz, Hermann M NiemeyerAbstract:Volatiles from wheat and oat seedlings elicited attraction in apterae and alatae Rhopalosiphum padi. Cereal volatiles were identified by GC-MS and olfactometric tests were performed with each compound. Attraction of aphids was elicited by (E)-2-hexenyl acetate, (Z)-3-hexenol, (E)-2-hexenyl acetate, (E)-2-hexenol, (Z)-2-hexenol, n-heptanal, n-octanal, n-nonanal, n-decanal, benzaldehyde, and linalool. The difference between the sensory capacity of alatae and apterae is discussed in relation to migrations between hosts during their life cycle.
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Activity of Enantiomers of Sulcatol on Apterae of Rhopalosiphum padi
Journal of Chemical Ecology, 1998Co-Authors: Andres Quiroz, Hermann M NiemeyerAbstract:GC-MS analysis of volatiles released from wheat infested with a high density of aphids showed the presence of 6-methyl-5-hepten-2-ol (sulcatol). The proportion of enantiomers present in the volatiles was determined by esterifying the mixture with (1S)-( − )-camphanic chloride and quantifying the esters. The mixture consisted of 75% (R)-( − ) and 25% (S)-( + ). The mixture of enantiomers as well as the racemate showed significant repellency towards apterous Rhopalosiphum padi in an olfactometer (15.7% and 14.4%, respectively, with 10 ng of stimulus). Single enantiomers or a mixture containing 25% (R)-( − )- and 75% (S)-( + )-enantiomers were inactive. The results are discussed in relation to the achievement of specificity by aphids in different pheromone-mediated behaviors.
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Semiochemicals mediating spacing behavior of bird cherry-oat aphid, Rhopalosiphum padi feeding on cereals
Journal of Chemical Ecology, 1997Co-Authors: Andres Quiroz, Lester J. Wadhams, Jan Pettersson, John A. Pickett, Hermann M NiemeyerAbstract:Olfactometry using an apterous individual of Rhopalosiphum padi (L.) showed an arresting effect by volatiles from a wheat seedling and a repellent effect by volatiles from a wheat seedling infested with aphids at a high population density (ca. 9 aphids/cm2). Four compounds, 6-methyl-5-hepten-2-one, (−)- and (+)-6-methyl-5-hepten-2-ol, and 2-tridecanone, were identified by GC-MS in air entrainments from the wheat seedlings with high aphid density but not from the wheat seedlings alone. The mixture of the four compounds in the natural proportion counteracted the attractivity of the volatiles from the intact uninfested wheat seedling. The likely role of these compounds in the spacing behavior of this aphid species, when present in high densities on wheat, is discussed.
Andres Quiroz - One of the best experts on this subject based on the ideXlab platform.
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olfactometer assessed responses of aphid Rhopalosiphum padi to wheat and oat volatiles
Journal of Chemical Ecology, 1998Co-Authors: Andres Quiroz, Hermann M NiemeyerAbstract:Volatiles from wheat and oat seedlings elicited attraction in apterae and alatae Rhopalosiphum padi. Cereal volatiles were identified by GC-MS and olfactometric tests were performed with each compound. Attraction of aphids was elicited by (E)-2-hexenyl acetate, (Z)-3-hexenol, (E)-2-hexenyl acetate, (E)-2-hexenol, (Z)-2-hexenol, n-heptanal, n-octanal, n-nonanal, n-decanal, benzaldehyde, and linalool. The difference between the sensory capacity of alatae and apterae is discussed in relation to migrations between hosts during their life cycle.
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Olfactometer-assessed responses of aphid Rhopalosiphum padi to wheat and oat volatiles
Journal of Chemical Ecology, 1998Co-Authors: Andres Quiroz, Hermann M NiemeyerAbstract:Volatiles from wheat and oat seedlings elicited attraction in apterae and alatae Rhopalosiphum padi. Cereal volatiles were identified by GC-MS and olfactometric tests were performed with each compound. Attraction of aphids was elicited by (E)-2-hexenyl acetate, (Z)-3-hexenol, (E)-2-hexenyl acetate, (E)-2-hexenol, (Z)-2-hexenol, n-heptanal, n-octanal, n-nonanal, n-decanal, benzaldehyde, and linalool. The difference between the sensory capacity of alatae and apterae is discussed in relation to migrations between hosts during their life cycle.
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Activity of Enantiomers of Sulcatol on Apterae of Rhopalosiphum padi
Journal of Chemical Ecology, 1998Co-Authors: Andres Quiroz, Hermann M NiemeyerAbstract:GC-MS analysis of volatiles released from wheat infested with a high density of aphids showed the presence of 6-methyl-5-hepten-2-ol (sulcatol). The proportion of enantiomers present in the volatiles was determined by esterifying the mixture with (1S)-( − )-camphanic chloride and quantifying the esters. The mixture consisted of 75% (R)-( − ) and 25% (S)-( + ). The mixture of enantiomers as well as the racemate showed significant repellency towards apterous Rhopalosiphum padi in an olfactometer (15.7% and 14.4%, respectively, with 10 ng of stimulus). Single enantiomers or a mixture containing 25% (R)-( − )- and 75% (S)-( + )-enantiomers were inactive. The results are discussed in relation to the achievement of specificity by aphids in different pheromone-mediated behaviors.
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Semiochemicals mediating spacing behavior of bird cherry-oat aphid, Rhopalosiphum padi feeding on cereals
Journal of Chemical Ecology, 1997Co-Authors: Andres Quiroz, Lester J. Wadhams, Jan Pettersson, John A. Pickett, Hermann M NiemeyerAbstract:Olfactometry using an apterous individual of Rhopalosiphum padi (L.) showed an arresting effect by volatiles from a wheat seedling and a repellent effect by volatiles from a wheat seedling infested with aphids at a high population density (ca. 9 aphids/cm2). Four compounds, 6-methyl-5-hepten-2-one, (−)- and (+)-6-methyl-5-hepten-2-ol, and 2-tridecanone, were identified by GC-MS in air entrainments from the wheat seedlings with high aphid density but not from the wheat seedlings alone. The mixture of the four compounds in the natural proportion counteracted the attractivity of the volatiles from the intact uninfested wheat seedling. The likely role of these compounds in the spacing behavior of this aphid species, when present in high densities on wheat, is discussed.
J. S. Bale - One of the best experts on this subject based on the ideXlab platform.
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Feeding behaviour of the aphid Rhopalosiphum padi (Hemiptera: Aphididae) on nitrogen and water-stressed barley (Hordeum vulgare) seedlings.
Bulletin of entomological research, 2001Co-Authors: K. L. Ponder, Richard Harrington, Jeremy Pritchard, J. S. BaleAbstract:Electrical penetration graphs (EPGs) were used to examine the probing behaviour of adult apterous Rhopalosiphum padi (Linnaeus) on barley seedlings grown under conditions of nitrogen or water stress. Aphids took significantly longer to reach and ingest from sieve elements of nitrogen-deficient seedlings than from nitrogen-sufficient seedlings but there were no such differences between water-stressed or well-watered seedlings. On both nitrogen and water-stressed seedlings the average length of each individual period of salivation into the sieve element was significantly greater compared with their respective unstressed controls.
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Effects of sublethal cold stress on the aphid Rhopalosiphum padi.
The Journal of Applied Ecology, 1994Co-Authors: L. A. Hutchinson, J. S. BaleAbstract:An anholocyclic clone of the aphid Rhopalosiphum padi was reared on leaves of barley seedlings at 20 °C in a 16:8 LD photoperiod. First instar nymphs and newly moulted, pre-reproductive adults were cooled at 1°C min −1 to − 5 and − 7.5 °C, respectively, for 1 and 6 h to represent increasing levels of sublethal cold stress. Surviving aphids were returned to 20 °C and a 16:8 LD photoperiod, after which observations were made on the rate of nymphal development, adult reproduction and longevity, and survival of progeny. Mean development time from birth to adult increased with increasing cold stress, ranging from 6.6 ± 0.14 days in the control to 10.3 ± 0.14 days in nymphs exposed to − 7.5 °C for 6 h (...)
Jens Weibull - One of the best experts on this subject based on the ideXlab platform.
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Glutamic acid content of phloem sap is not a good predictor of plant resistance to Rhopalosiphum padi
Phytochemistry, 1994Co-Authors: Jens WeibullAbstract:Abstract The phloem sap content of glutamic acid was determined in EDTA leaf exudate samples from a collection of Hordeum vulgare subsp. spontaneum previously screened for Rhopalosiphum padi resistance. Segregating populations of crosses between subsp. spontaneum X cultivated barley were also evaluated. The concentration of glutamic acid was significantly inversely correlated with aphid performance on the spontaneum lines. However, no relationship between glutamic acid concentration and R. padi resistance was observed in segregating material. Causes for this are discussed.
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Resistance to Rhopalosiphum padi (Homoptera: Aphididae) in Hordeum vulgare subsp. spontaneum and in hybrids with H. vulgare subsp. vulgare
Euphytica, 1994Co-Authors: Jens WeibullAbstract:Accessions of Hordeum vulgare subsp. spontaneum, the progenitor of cultivated barley, were screened in field and glasshouse trials for resistance to the aphid Rhopalosiphum padi. A few selected lines were furthermore hybridized with a modern barley variety and the resulting populations evaluated. High levels of resistance were found among some of the ‘spontaneum’ accessions resulting in lower aphid growth rates (maximum reduction 57%). Segregation patterns among siblings in F2 populations were continuous, indicating the presence of several genes with possibly additive effects. The usefulness of H. vulgare subsp. spontaneum for breeding aphid resistant barley is discussed.
Han Zhao-jun - One of the best experts on this subject based on the ideXlab platform.
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Cloning and sequence analysis of fragments of acetylcholinesterase genes from Rhopalosiphum padi(Linnaeus) and Sitobion avenae(Fabricius)
Journal of Nanjing Agricultural University, 2006Co-Authors: Han Zhao-junAbstract:Using degenerate primers and RT-PCR technique,two cDNA fragments of acetylcholinesterase genes were cloned from both Rhopalosiphum padi(Linnaeus)and Sitobion avenae(Fabricius)and were named as Rp.ace1,Rp.ace2,Sa.ace1 and Sa.ace2,respectively.They were 282,282,264 and 572 bp in length,and encodes 94,94,88 and 190 amino acids,respectively.Sequence analysis showed that Rp.ace1 and Sa.ace1 had more than 96% homology with the Ace1 from Aphis gossypii and Myzus persicae.Rp.ace2 and Sa.ace2 had more than 95% homology with the Ace2 from these two aphids and the Schizaphis graminum.Results implied that both Rhopalosiphum padi(Linnaeus)and Sitobion avenae(Fabricius)have two acetylcholinesterase genes,and the two genes may be popular in all aphids and both functional.