Effect of methoxyphenols on grain aphid feeding behaviour

Methoxyphenols might be important in the resistance of cereals to aphids. Electrical penetration graph (EPG) recordings were used to determine the effect of caffeic, ferulic and sinapic acids, and scopoletin on the feeding behaviour of the grain aphidSitobion avenae (F.). Aphids on wheat seedlings treated systemically with these phenols showed reduced ingestion of phloem sap and salivation into sieve elements in most cases. The earlier pathway phases of probing were prolonged. Moreover increase in number of probes as well as reduction of total time of probing was observed. In addition, no O-demethylase activity was found in homogenates of aphids fed on moderately-resistant (phenolic rich) or susceptible (phenolic poor) wheat varieties. The significance of these results for understanding the resistance of cereals to aphids is discussed.     

The spatial and temporal distribution of the grain aphid Sitobion avenae in winter wheat

The spatial and temporal distribution of the grain aphid Sitobion avenae F. (Homoptera: Aphididae) was studied within a field of winter wheat during the summer of 1996. Sampling was done using four nested grids comprising 133 locations. Analysis by Taylor's power law gave results typical for insect populations. Analysis by SADIE (Spatial Analysis by Distance Indices) showed spatial pattern due to edge effects and sampling scale, and positive but mild spatial association, although spatial patterns were ephemeral. Reasons for these findings and the implications for integrated crop management are discussed.     

Biochemical basis of winter wheat resistance to the grain aphid, Sitobion avenae

Six winter wheat cultivars with differing degrees of resistance to the grain aphid, Sitobion avenae (F.), were studied under field conditions. Resistance was measured in terms of non-preference and antibiosis on plants at seven growth stages. The varieties Saga and Grana were most resistant in terms of both non-preference and antibiosis to S. avenae at all growth stages examined. The varieties Liwilla and Dana were relatively susceptible to aphid attack. The number of aphids was directly proportional to the total content of free and essential amino acids. The level of resistance showed a similar, but not identical, relationship with the observed concentration of soluble proteins. A higher degree of cultivar resistance was associated with a higher value on a toxicity index, which is the ratio between the free-phenols and free-amino acids content. Obtained results suggest that the resistance of winter wheat cultivars to the grain aphid was based mainly on the mechanism of antibiosis.

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Résumé Six cultivars de blé d'hiver, présentant différents degrés de résistance au puceron des grains, S. avenae, ont été étudiés dans la nature. La résistance a été évaluée en fonction de l'antibiose et de l'absence de préférence de plantes à 7 stades de développement. Les variétés Saga et Grana ont été les plus résistantes, suivant ces deux critères, pour tous les stades de puceron étudiés. Les variétés Liwilla et Dana ont été relativement sensibles. Les effectifs de pucerons étaient proportionnels à la teneur totale en acides aminés libres essentiels. Les concentrations en protéines solubles présentent une relation de même type, mais pas identique, avec le niveau de résistance. Un haut degré de résistance a été associé à une valeur élevée de l'indice de toxicité, rapport entre les phénols libres et la teneur en acides aminés libres. Ces résultats suggèrent une résistance des cultivars de blé d'hiver à S. avenae liée principalement aux mécanismes d'antibiose.

     

Changes in phenylalanine and tyrosine content and metabolism in ears of susceptible and aphid resistant winter wheat cultivars upon infestation by Sitobion avenae

Changes in free phenylalanine and tyrosine content and metabolism in the ears of susceptible Bezostaya 1 and relatively resistant Atlas 66 winter wheat varieties after natural infestation by the grain aphid (Sitobion avenae) (F.) were investigated. After infestation the content of phenylalanine and tyrosine in the variety Atlas 66 was higher than in the susceptible cultivar Bezostaya 1. Attack by aphids also brought changes in the metabolism of phenylalanine and tyrosine in the tissues. A higher phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) activity was observed in ear tissues of the more resistant variety Atlas 66. The changes in the activity of those lyases in Atlas 66 were strictly correlated with the increase of phenylalanine and tyrosine content after infestation.

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Résumé L'étude a porté sur l'analyse des teneurs en phénylalanine et tyrosine libres et sur le métabolisme des épis de blés d'hiver, — sensible Bezostaya 1 et relativement résistant Atlas 66 —, après une attaque naturelle du puceron des grains, S. avenae F. Les teneurs en phénylalanine et en tyrosine d'Atlas 66 sont alors supérieures à celles de Bezostaya 1. Les attaques de pucerons provoquent des changements dans le métabolisme de la phénylalanine et de la tyrosine des tissus. Des activités phénylalanine ammonialyase (PAL) et tyrosine ammonialyase (TAL) ont été observées dans les tissus des épis de la variété la plus résistante, Atlas 66. Les modifications de l'activité de ces lyases dans les pieds du cultivar résistant Atlas 66 présentent une relation étroite avec l'accroissement des teneurs en phénylalanine et en tyrosine après la contamination.

     

Impact of intercropping aphid-resistant wheat cultivars withoilseed rape on wheat aphid (Sitobion avenae) and its natural enemies

The effects of intercropping of wheat cultivars and oilseed rape on the densities of wheat aphid, Sitobion avenae, and their arthropod natural enemies were evaluated. Three winter wheat cultivars with different resistant levels to S. avenae were used: ‘KOK’ (high resistance), ‘Xiaobaidongmai’ (low resistance) and ‘Hongmanghong’ (susceptible). The results showed that the densities of S. avenae were significantly higher on the monoculture pattern than on either the 8-2 intercropping pattern (eight rows of wheat with two rows of oilseed rape) or the 8-4 intercropping pattern (eight rows of wheat with four rows of oilseed rape). The mean number of predators and the mummy rates of S. avenae were significantly higher in two intercropping patterns than those in the monoculture pattern. The densities of S. avenae, ladybeetles, and mummy rate of S. avenae were significantly different among different wheat cultivars. The highest densities of S. avenae and ladybeetles were found on wheat cultivar Hongmanghong. The lowest densities of S. avenae associated with high mummy rate of S. avenae were found on wheat cultivar Xiaobaidongmai. The results showed that wheat-oilseed rape intercropping conserved more predators and parasitoids than in wheat monoculture fields, and partial resistance of wheat cultivar Xiaobaidongmai had complementary or even synergistic effects on parasitoid of S. avenae.     

Methods of hatching the eggs and rearing the fundatrices of the English grain aphid, Sitobion avenae

Several methods for hatching the eggs and rearing individuals of the first generation (fundatrices) of Sitobion avenae were investigated. The most successful methods were incubation of the eggs on grass seedlings at 2°C and rearing the fundatrices on grass seedlings (overall survival 66%) and incubation of the eggs in plastic boxes at 2°C and rearing the fundatrices on wheat seedlings (overall survival 62%).

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Résumé L'éclosion des oeufs de S. avenae peut être induite par le transfert à 10°C ou 12°C, après une incubation de 75–120 jours à 2°C. Le pourcentage le plus élevé d'éclosions a été obtenu quand les oeufs avaient incubé pendant 100 à 110 jours à 2°C (67% at 71.5% respectivement) dans des petites boîtes de plastique, ou pendant 100 jours à 2°C sur des pousses de graminées (73.5%). Si les oeufs sont pondus sur blé, la plante ne peut pas tolérer la période d'incubation, mais cet obstacle peut être surmonté en obligeant les ovipares à pondre leurs oeufs sur de pousses de graminées, comme Poa annua, hôte convenable pour les fondatrices. Les ovipares peuvent aussi pondre sans difficultés sur autre chose que des végétaux, et des récipients peuvent ètre mis à incuber sans contenir du matériel végétal.

     

3个新引进小麦品种对麦长管蚜抗性的初步研究

以小偃-22和Amigo(美国)为对照对麦长管蚜在3个新引进小麦品种Astron、Batis和Xanthos(德国)上的抗蚜性进行了测定。在室内控制条件下,麦长管蚜在5个品种上的发育历期(DD)、体重差(dW)、相对日均体重增长率(MRGR)和生殖力(F)的测定结果表明,Astron、Xanthos与Amigo、小偃-22的抗性水平相当,均优于Batis;在大田自然条件下,通过对不同品种在不同生育期的感蚜指数以及感蚜量动态曲线的监测分析表明,Astron、Xanthos在我国的抗蚜水平与抗性品种Amigo的抗蚜性水平相当,优于Batis和小偃-22。可初步说明Astron、Xanthos在我国也具有较好的抗蚜性,可作为我国抗蚜育种材料。     

The effect of hydoroxamic acid concentration at late growth stages of wheat on the performance of the aphid Sitobion avenae

From a previous worldwide screen of wheat cultivars as seedings, five were selected to encompass a wide concentraiton range of the hydroxaminc acid DIMBOA (0.99-8.07 mmol Kg ^-1 fr. wt). Compared with those in seedings, the concentrations of DIMBOA in flag leaves of the same cultivars were relatively low (0.06-0.87 mmol kg^-1 fr. wt). Concentraions of hydroxamic acids in whole ears at anthesis and the early milk stage were even lower, ranging from undetectable to 0.05 mmol kg^-1 fr. wt. The three-day mean relaive growth rate (MRGR) was determined for nymphs of Sitobion avenace on the flag leaf (GS 39) and on the ear (GS 60-60) of the five cultivars. No significant differences in MRGR were found between cultivatrs at the same growth stage, although MRGR was higher on ears on than on flag leaces. The results are discussed in realtion to the potential of hydroxamic acids in programmses aimed at breeding mature-plant aphid resistance into wheat cultivars.     

我国麦蚜抗药性及研究现状

麦蚜是危害我国小麦Triticum aestivum L.生产的主要害虫,具有分布广、数量大、繁殖力强以及远距离迁飞等特点,不仅直接吸食小麦汁液,还传播多种植物病毒,每年造成小麦减产10%~30%。目前对麦蚜的防控主要以化学防治为主,但由于化学杀虫剂长期或不合理的使用,多地麦蚜对常用杀虫剂产生了不同程度的抗性。本文从麦蚜抗药性测定方法、抗性水平及交互抗性、代谢和靶标抗性机制、以及麦蚜抗药性综合治理等方面进行了综述,以期为麦蚜的防治及杀虫剂的持续合理使用提供理论参考和依据。     

Mobility of apterous grain aphids Sitobion avenae within wheat fields

In a field study of the grain aphid Sitobion avenae (F.) almost all apterous aphids were found to move from the natal ear before reproducing, and alatiform nymphs usually moved between ears during their development. Apterae were very mobile, with over 50% staying on one ear for less than 24 h. Movements did not appear to be a response to climatic conditions, predation or colony density.

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Résumé Lors de l'étude de Sitobion avenae dans la nature, on a constaté que presque tous les individus aptères avaient quitté leur épi d'origine avant la reproduction, et que les larves de type ailé s'étaient déplacées généralement entre les épis pendant leur développement. Les aptères étaient très mobiles, la majorité restant moins de 24 h sur le même épi. Ces déplacements n'ont pas semblé dépendre des conditions climatiques, de la prédation ou de la densité des colonies.

     

Effect of wheat resistance, the parasitoid Aphidius rhopalosiphi, and the entomopathogenic fungus Pandora neoaphidis, on population dynamics of the cereal aphid Sitobion avenae

The influence of wheat (Triticum aestivumL.) resistance, the parasitoid Aphidius rhopalosiphiDe Stephani-Perez (Hymenoptera: Braconidae) and the entomopathogenic fungus Pandora neoaphidis(Remaudière et Hennebert) Humber (Zygomycetes: Entomophthorales) on the density and population growth rate of the cereal aphid Sitobion avenae(F.) (Hemiptera: Aphididae) was studied under laboratory conditions. Partial wheat resistance was based on hydroxamic acids, a family of secondary metabolites characteristic of several cultivated cereals. The partial resistance of wheat cultivar Naofén, the action of the parasitoid and the joint action of the parasitoid and fungus, reduced aphid density. The lowest aphid densities were obtained with the combination of the parasitoid and the fungus, but wheat resistance under these circumstances did not improve aphid control. Significant reductions of population growth rate (PGR) of aphids were obtained with the joint action of wheat resistance and natural enemies. In particular, the combined effects of parasitoids and fungi showed significantly lower PGR than the control without natural enemies in both wheat cultivars. Our results support the hypothesis that wheat resistance and the utilization of biological control agents could be complementary strategies in an integrated pest management program against cereal aphids.     

Reproductive stragegies of the alate and apterous morphs of the grain aphid, Sitobion avenae

Differences were observed in the total fecundity and patterns of reproduction of four morphs of Sitobion avenae (F.). The reproductive rates of apterous and alate exules declined gradually with time but decreased rapidly in gynoparae and oviparae. Under short daylengths apterous exules gave birth in three phases; the first consisting mainly of gynoparae, the second of males and the third of non-gynoparous viviparae. The strategic importance of the sequence of morphs and the reproductive behaviour of each is discussed in relation to the maximization of overwintering population size.

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Stratégies reproductives des types ailés et aptères de Sitobion avenae F.

Résumé Des différences ont été observées entre les fécondités totales et les modes de reproduction de quatre types de Sitobion avenae. Les taux de reproduction diminuent graduellement dans le temps chez les aptères et ailés virginopares et rapidement chez les gynopares et ovipares. En photophases courtes, les virginopares aptères donnent naissance à trois types: le premier composé essentiellement de gynopares, le second de mâles et le troisième de vivipares. L'importance stratégique de la succession des types et du comportement reproducteur de chacun est discutée en relation avec l'accroissement maximum de la taille de la population hivernante.

     

Quantification of the impact of the hoverfly, Metasyrphus corollae on the cereal aphid, Sitobion avenae, in winter wheat: laboratory rates of kill

The rate of kill of cereal aphids by larvae of Metasyrphus corollae (F.) (Diptera: Syrphidae) was measured in the laboratory with the aim of assessing the impact of this predator on field populations of cereal aphids. Daily measurements were taken of changes in both the larval weight and the biomass of aphids killed by M. corollae in conditions of constant temperature and humidity. A mean relative kill rate was defined and calculated for each larval instar of the predator from which estimates of field daily rates of kill can be made.

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Quantification de l'impact de Metasyrphus corolae sur Sitobion avenae sur blé d'hiver: taux de mortalité au laboratoire

Résumé Le taux de mortalité de S. avenae provoqué par les larves de M. corollae a été mesuré au laboratoire pour évaluer l'impact de ce prédateur sur les populations de ce puceron dans la nature. L'évolution du poids des larves et de la biomasse de pucerons tués a été suivie tous les jours dans des conditions de température et humidité constantes. Un taux moyen de mortalité a été déterminé pour chaque stade larvaire du prédateur, il a servi à déduire les niveaux de mortalité quotidienne dans les champs.

     

Microsatellite markers linked to six Russian wheat aphid resistance genes in wheat

The Russian wheat aphid (RWA), Diuraphis noxia Mordvilko, is a serious economic pest of wheat and barley in North America, South America, and South Africa. Using aphid-resistant cultivars has proven to be a viable tactic for RWA management. Several dominant resistance genes have been identified in wheat, Triticum aestivum, including Dn1 in PI 137739, Dn2 in PI 262660, and at least three resistance genes (Dn5+) in PI 294994. The identification of RWA-resistant genes and the development of resistant cultivars may be accelerated through the use of molecular markers. DNA of wheat from near-isogenic lines and segregating F₂ populations was amplified with microsatellite primers via PCR. Results revealed that the locus for wheat microsatellite GWM111 (Xgwm111), located on wheat chromosome 7DS (short arm), is tightly linked to Dn1, Dn2 and Dn5, as well as Dnx in PI 220127. Segregation data indicate RWA resistance in wheat PI 220127 is also conferred by a single dominant resistance gene (Dnx). These results confirm that Dn1, Dn2 and Dn5 are tightly linked to each other, and provide new information about their location, being 7DS, near the centromere, instead of as previously reported on 7DL. Xgwm635 (near the distal end of 7DS) clearly marked the location of the previously suggested resistance gene in PI 294994, here designated as Dn8. Xgwm642 (located on 1DL) marked and identified another new gene Dn9, which is located in a defense gene-rich region of wheat chromosome 1DL. The locations of markers and the linked genes were confirmed by di-telosomic and nulli-tetrasomic analyses. Genetic linkage maps of the above RWA resistance genes and markers have been constructed for wheat chromosomes 1D and 7D. These markers will be useful in marker-assisted breeding for RWA-resistant wheat. Received: 17 May 2000 / Accepted: 13 June 2000     

Production of sexual morphs by the monoecious cereal aphid Sitobion avenae

The effects of photoperiod and temperature on the production of sexual forms by two clones of Sitobion avenae, the grain aphid, were examined. One clone did not produce sexual forms, whereas the other did under conditions of short light (<14 h) and low temperature (15°C). Temperature and photoperiod interacted to some extent both in the production of oviparae and of males. Even when the sexual forms were produced there was always a proportion of virginoparae.

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Production de sexués par Sitobion avenae, puceron monoécique

Résumé Un clone de Sitobion avenae a produit sans difficulté jusqu'à 7 générations de sexués en réaction à des photopériodes courtes (<14 h) et à de faibles températures (15°C) tandis qu'un autre clone n'en produit aucune.La proportion de sexués différait suivant les parents. La production de mâles avait une nette tendance à apparaître lors des reproduction les plus tardives. Dans les générations tardives avec jours courts, les vivipares (virginopares et gynopares) avaient eu tendance à être produits à la fin de la période de reproduction.Les gynopares (c'est à dire les parents d'ovipares) de S. avenae étaient surtout aptères, mais comprenaient beaucoup plus d'ailés que les virginopares obtenus dans les mêmes conditions. Un vivipare était induit comme gynopare (ou ses embryons étaient déterminés comme ovipares) avant la naissance, mais cette détermination pouvait apparemment encore être inversée en soumettant l'insecte à de longues photopériodes et à de hautes températures jusqu'à deux jours après la naissance.Aucun S. avenae ovipare n'a été produit jusqu'à la troisième génération. Aucun ovipare n'a été produit avec des photopériodes supérieures à 13 H 30 à 10°C, 13 H à 15°C et 8 H à 20°C. La proportion d'individus produisant des ovipares à 15°C a été plus faible qu'à 10°C pour toutes les photopériodes, et à cette dernière température beaucoup plus de vivipares étaient gynopares que virginopares.Les basses températures ont été vraisemblablement le facteur dominant de stimulation de la production de mâles de S. avenae, mais cependant il semble qu'un plus grand nombre de mâles a été produit aux températures et photopériodes intermédiaires qu'aux extrêmes.La capture de mâles ailés de S. avenae dans des pièges à succion a été généralement limitée à Octobre-soit à peu prés le moment prévu par les expériences de laboratoire. Des mâles de S. avenae sont aussi capturés fréquemment et été, ce qui peut être lié à des hivers précédents doux.

     

A field evaluation of different criteria for determiningthe need to treat winter wheat against the grain aphid Sitobion avenae and the rose-grain aphid Metopolophium dirhodum

The economics of control of grain aphid (Sitobion avenae) and rose-grain aphid (Metopolophium dirhodum) were investigated in a series of experiments carried out across England in 1988 and 1989. Sprays of pirimicarb or dimethoate were applied at three growth stages and yield effects measured. Aphid infestations were determined by a range of different methods, to evaluate the value of each for decision making. Aphids overwintered in crops in mild conditions in both seasons, resulting in early population build-up and decline in many cases. Aphicide sprays applied during the booting stage increased average yields by 0.26 t/ha. Profitability of the treatment strategies considered was not greatly enhanced by selective spray application related to aphid assessment at this stage. Delaying decision making to the flowering or grain-filling stages resulted in reduced profitability. A poor correlation between aphid numbers and crop yield response to sprays was found. This was shown to be due to differences in subsequent aphid population development and in aphicide efficacy. Grain quality was affected only by high aphid infestations which caused large yield reductions.     

The cost of switching from asexual to sexual reproduction in an aphid

The fecundity of asexual and sexual morphs of Sitobion avenae (F.) is compared. The cost of sex is quantified in terms of the reduction in numbers of offspring produced. The cost is much greater than the halving of fecundity that is usually assumed to be associated with the production of males.

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Résumé Les fécondités des virginipares ailés, des gynopares ailés et des ovipares d'un même clone de Sitobion avenae ont été déterminées à 12°C. Bien que les types qui ayant donné naissance à des sexués aient eu une fécondité initiale plus élevée que celle de la lignée asexuée, celle-ci a été significativement plus féconde après 15 jours de reproduction.Les résultats du laboratoire ont été utilisés pour évaluer la fécondité de lignées sexuées et asexuées pendant quatre générations à 12°C. La reproduction parthénogénétique a présenté un avantage numérique sur la reproductions sexuée dans le rapport 320/1. La reproduction sexuée a été accompagnée d'une diminution significative de la fécondité potentielle. Bien que la reproduction sexuée de S. avenae soit avantageuse dans les régions où les hivers sont durs, parce que les oeufs sont résistants au froid, les lignées asexuées présentent un avantage considérable en ce qui concerne la fécondité potentielle pour l'augmentation de la population en automne et elles conservent de plus la capacité d'un accroissement numérique ultérieur si l'hiver est doux.

     

Microsatellite-based molecular diversity of bread wheat germplasm and association mapping of wheat resistance to the Russian wheat aphid

Genetic diversity of a set of 71 wheat accessions, including 53 biotype 2 Russian wheat aphid (RWA2)-resistant landraces and 18 RWA2 susceptible accessions, was assessed by examining molecular variation at multiple microsatellite (SSR) loci. Fifty-one wheat SSR primer pairs were used, 81 SSR loci were determined, and 545 SSR alleles were detected. These SSR loci covered all the three genomes, 21 chromosomes, and at least 41 of the 42 chromosome arms. Diversity values averaged over SSR loci were high with mean number of SSR alleles/locus = 6.7, mean Shannon’s index (H) = 1.291, and mean Nei’s gene diversity (He) = 0.609. The three wheat genomes ranked as A > D > B and the homoeologous groups ranked as 7 > 3  > 1 > 2 > 6 > 5 > 4 based on the number of alleles per locus. Xgwm136 on chromosome arm 1AS is the most polymorphic SSR locus with the largest number of observed and effective alleles and the highest H and He. Among all 2485 pairs of wheat accessions, genetic distance (GD) ranged from 0.054 to 1.933 and averaged 0.9832. A dendrogram based on GD matrix showed that all the wheat accessions could be grouped into distinct clusters. Most of the susceptible cultivars (13/18) were clustered into groups that contains all or mostly susceptible accessions. Most of the U.S. cultivars belong to a group that is distinguishable from all the different RWA2 resistant groups. Diversity analysis was also conducted separately for subgroups containing 53 RWA2-resistant accessions and 18 RWA2-susceptible accessions. Association mapping revealed 28 SSR loci significantly associated with leaf chlorosis, and 8 with leaf rolling. New chromosome regions associated with RWA2 resistance were detected, and indicated existence of new RWA resistance genes located on chromosomes of all other homoeologous groups in addition to the groups 1 and 7 in bread wheat. This information is helpful for development of mapping populations for RWA2 resistance genes from different phylogenetic groups, and for wise utilization of the RWA-resistant germplasm in wheat breeding programs.     

Genetic mapping of Dn7, a rye gene conferring resistance to the Russian wheat aphid in wheat

The Russian wheat aphid is a significant pest problem in wheat and barley in North America. Genetic resistance in wheat is the most effective and economical means to control the damage caused by the aphid. Dn7 is a rye gene located on chromosome 1RS that confers resistance to the Russian wheat aphid. The gene was previously transferred from rye into a wheat background via a 1RS/1BL translocation. This study was conducted to genetically map Dn7 and to characterize the type of resistance the gene confers. The resistant line '94M370' was crossed with a susceptible wheat cultivar that also contains a pair of 1RS/1BL translocation chromosomes. The F₂ progeny from this cross segregated for resistance in a ratio of 3 resistant: 1 susceptible, indicating a single dominant gene. One-hundred and eleven RFLP markers previously mapped on wheat chromosomes 1A, 1B and 1D, barley chromosome 1H and rye chromosome 1R, were used to screen the parents for polymorphism. A genetic map containing six markers linked to Dn7, encompassing 28.2 cM, was constructed. The markers flanking Dn7 were Xbcd1434 and XksuD14, which mapped 1.4 cM and 7.4 cM from Dn7, respectively. Dn7 confers antixenosis, and provides a higher level of resistance than that provided by Dn4. The applications of Dn7 and the linked markers in wheat breeding are discussed.Communicated by J. Dvorak     

Changes in the levels of plant total phenols and free amino acids induced by two cereal aphids and effects on aphid fecundity

Abstract:  Phenols and amino acids have previously been involved in the resistance of cereals to aphids. In the present study, the mean total concentrations of both compounds were quantitatively estimated from leaf-tissue samples collected at three growth stages (third, fifth and seventh leaf stages) from maize and barley seedlings and then correlated with the mean 7-day fecundity of Rhopalosiphum padi (L.) and Sitobion avenae (F.) (Homoptera, Aphididae) reared separately on the corresponding growth stages of each cereal. Results revealed an inverse correlation between the total concentration of each chemical in aphid-infested maize and barley plants and the fecundity of each aphid on every growth stage of the cereals. Moreover, R. padi led to an increase in total amino acids when reared on maize or barley without affecting the phenol concentration, while S. avenae induced a decrease in phenol levels but did not change the total amino acids on each growth stage of the plants. The significance of these results for understanding potential differences in requirements of cereal aphids for host selection and acceptance are discussed.