Bird Cherry-oat Aphid Rhopalosiphum Padi Research Articles

Interactions among three species of cereal aphids simultaneously infesting wheat

Interactions among greenbug, Schizaphis graminum (Rondani), Russian wheat aphid, Diuraphis noxia (Mordvilko), and bird cherry-oat aphid Rhopalosiphum padi (L.) were examined on wheat plants (Triticum aestivum L., cultivar TAM 107). Nymphs were released on the plants as conspecific and heterospecific pairs of either first or fourth instars and evaluated for survival, developmental time, fecundity, intra-plant movement, and affinity to plant tissues. Survival from first instar to onset of reproduction averaged 90-100% across all pair combinations. Diuraphis noxia developed faster as conspecifics than in any heterospecific combination, and faster as conspecifics feeding on the same plant tissue than on different tissues. Fecundity of S. graminum was higher for conspecifics that developed on the same plant tissue than for those feeding separately. There was evidence of amensalism (one species was harmed while the other was unaffected) in that D. noxia experienced delayed development feeding in tandem with S. graminum, and reduced fecundity with both S. graminum and R. padi. Furthermore, S. graminum nymphs had reduced survival when their mothers matured on a same plant with R. padi. Both D. noxia and R. padi changed position on the plant more often when developing with S. graminum. Survival of second generation S. graminum nymphs was reduced when this species developed and reproduced in tandem with R. padi. Preferred feeding locations were S. graminum--primary leaf, D. noxia--tertiary leaf and R. padi--stem and these were not altered in any heterospecific combinations. Heterospecific aphids had no impact on fecundity or progeny survival in any species combination when fourth instars matured and reproduced on plants not previously exposed to aphid feeding, supporting the inference that systemic, aphid-induced changes in plant physiology mediated the effects observed when first instars developed and reproduced on the same plants.

Plant resistance to the Russian wheat aphid: effects on a nontarget aphid and the role of induction

AbstractSeveral resistant lines of wheat, Triticum aestivum (L.) (Poaceae), have been developed to control populations of the Russian wheat aphid, Diuraphis noxia (Mordvilko) (Hemiptera: Aphididae). We examined the potential effects of D. noxia resistant lines on another aphid, the bird cherry-oat aphid (Rhopalosiphum padi (L.) (Hemiptera: Aphididae)), which commonly co-occurs with D. noxia. Because one type of resistance (mediated by the Dn1 gene) is purported to be induced rather than constitutive, we also determined the degree to which the suitability of resistant and susceptible plants is modified by previous infestation. Although resistant lines were derived from five different sources, we did not detect any differences in the population growth of R. padi on resistant and near-isogenic susceptible plants. The performance of D. noxia was reduced as expected on resistant plants but was unaffected by whether or not plants had been previously infested. In contrast, the performance of R. padi was reduced on plants that had been previously infested but was unaffected by whether plants were resistant or susceptible to D. noxia. Because neither species' performance was especially low on previously infested, resistant plants, there was no evidence that prior aphid feeding induces a higher level of resistance.

Effects of different atmospheric CO2 concentrations and soil moistures on the populations of bird cherry-oat aphid (Rhopalosiphum padi) feeding on spring wheat

Spring wheat plants were grown in pots at three CO2 concentrations (350, 550 and 700 ppm) and three soil water levels (40, 60 and 80% of field water capacity) in field open top chambers and were infested with bird cherry-oat aphids (Rhopalosiphum padi Linnaeus). Aphid population dynamics were recorded throughout the growing season and analysis of the chemical composition of spring wheat leaves was conducted at the same time. Results showed that: (1) Aphid populations increased with raised atmospheric CO2 concentrations. (2) The aphid populations showed different responses to different CO2 concentrations. The population size, population growth rate and population density found under the 350 ppm CO2 treatment was far less than those recorded under the 550 and 700 ppm CO2 treatments. The population size, population growth rate and population density recorded under the 700 ppm CO2 treatment was slightly higher than those recorded under the 550 ppm CO2 treatment. (3) The effect of CO2 concentration on the aphid population was correlated with soil water level. The highest aphid population size was achieved under the 60% soil water treatment. (4) Atmospheric CO2 and soil moisture had significant effects on the chemical composition of the wheat leaves. (5) Aphid population size correlated positively with the concentration of leaf water content, soluble proteins, soluble carbohydrates and starch, while correlating negatively with the concentration of DIMBOA and tannin.

Yield increase attributable to aphid predation by ground-living polyphagous natural enemies in spring barley in Sweden

It has been claimed that natural enemies of pests perform important ecosystem services in agricultural landscapes. These services have rarely been evaluated in yield or monetary terms at farm level. We have examined the degree to which ground-living natural enemies of the bird cherry-oat aphid ( Rhopalosiphum padi (L.)) reduced aphid abundance and influenced barley yields on ten commercial farms in central Sweden. On average, ground-living natural enemies of pests increased barley yields by 303 kg/ha. This corresponded to a potential 52% reduction in yield loss from R. padi compared with a scenario where no natural enemies were present. Measured as the percentage increase of actual yield, ground-living natural enemies of aphids increased the yield by 23%. The increase in yields in absolute terms was larger on conventional farms than organic farms, but the percentage increase of yields was larger on organic farms. The study only considered 1 year, with high aphid abundance. However, we also discuss the effects of predators as well as insecticides in the long-term. Our study shows that yield increases attributable to predators can be compared with yield increases from insecticide use for the evaluation of different management strategies.

Distribution of bird cherry-oat aphids ( Rhopalosiphum padi (L.)) in relation to landscape and farming practices

Apterous aphids show varying degrees of aggregation in the field. Both alate and apterous Rhopalosiphum padi (L.) were compared in terms of degree of aggregation in relation to landscape features and farming management (conventional vs. organic). Alate R. padi were clearly aggregated, but no effect of landscape features or farming management was found on the degree of aggregation. Apterous R. padi were aggregated, and to a degree that varied according to field. Aggregation tended to be lower in landscapes with high perimeter-to-area ratios of the fields, but there was no significant difference between organically and conventionally managed fields. The fields with low aggregation had few alate, low R. padi population growth rate and therefore a low abundance.

Aphid infestation induces PR-proteins differently in barley susceptible or resistant to the birdcherry-oat aphid (Rhopalosiphum padi)

The effect of infestation by the birdcherry-oat aphid (Rhopalosiphum padi L.), on induction of PR-proteins was investigated in barley (Hordeum vulgare L.), using barley lines susceptible or resistant to R. padi. The PR-proteins PR-1a (unknown function), PR-5a (acidic thaumatin) and peroxidase (EC 1.11.1.7) were not affected, whereas one chitinase (EC 3.2.1.14) and 4 β-1,3-glucanases (EC 3.2.1.39) were induced by the aphid treatment. In the resistant breeding line CI 16145, but not in the susceptible cultivar Golf, accumulation of one basic chitinase and two acidic β-1,3-glucanases increased with time from 2 until 11 days after infestation, as determined by western blots, with antibodies raised against purified chitinase (PR-3a) and β-1,3-glucanase (PR-2a) from barley. By isoelectric focusing, two additional basic β-1,3-glucanases were detected, which increased after infestation in both the resistant and the susceptible barley. The basic chitinase was only detected at days 7 and 11 in the susceptible cultivar, but already at day 2 in the resistant line. The induction was localized to the infested leaf. The PR-proteins PR-3a and PR-2a were also induced by the fungal pathogen (Blumeria [syn. Erysiphe] graminis f. sp. hordei), methyl salicylate and, to a lower extent, by wounding with tweezers and methyl jasmonate (MeJA). Needle wounding performed to mimic aphid stylet penetration did not induce chitinase or β-1,3-glucanase. It is concluded that the fungal pathogen and the aphid infestation induce both similar and different responses, and that the aphid induction is not due to wounding only. The different responses in resistant and susceptible lines indicate that the induced enzymes may play a role in the resistance against aphid infestation.

Winter Wheat Responses to Bird Cherry‐Oat Aphids and Barley Yellow Dwarf Virus Infection

Grain yield loss caused by bird cherry‐oat aphid (Rhopalosiphum padi L.) infestation and barley yellow dwarf virus (BYDV) infection may result from direct damage to the winter wheat (Triticum aestivum L.) crop as well as from reduced crop tolerance to stress environments. This greenhouse study measured the effects of R. padi infestation, BYDV infection, or a combination of R. padi plus BYDV on plant height, date of anthesis, yield, and yield components of four winter wheat varieties (‘Roughrider’, ‘Norstar’, ‘TAM 107’, and ‘Vona’) in the absence of additional environmental stresses. Treatments were applied at the two‐leaf growth stage. Early in the pre‐vernalization growth period, R. padi treatment (alone or in combination with BYDV) reduced plant height to about 55 to 60% of the control plant height while BYDY treated plants were about 90% of control. During the post‐vernalization growth period, plant heights attained about 90% of control in the R. padi treatment, to about 80% of control in the BYDV treatment and to about 70% of control in the R. padi+ BYDV treatment. Dates of anthesis were later in the R. padi+BYDV treatments than in the R. padi treatments for Norstar, Roughrider, and Vona but not for TAM 107. Individual kernel weights in the BYDV and R. padi+BYDV treatments were less than control or R. padi treatments for Norstar, TAM 107, and Vona but not for Roughrider. Control or R. padi‐treated plants had a greater number of fertile heads than plants given the BYDV or R. padi+BYDV treatments. Grain yield was strongly associated with kernel number per plant. The number of kernels per plant was reduced 19% by the R. padi treatment, 36% by the BYDV treatment, and 50% by the R. padi+BYDV treatment. Grain yield was reduced 21% by the R. padi treatment, 46% by the BYDV treatment, and 58% by the R. padi+BYDV treatment. With the exception of date of anthesis and individual kernel weight, there were no significant treatment by variety interactions for plant height, grain yield, and yield components. We conclude that R. padi infestation and BYDV infection caused significant yield reductions and that the varieties tested had little difference in their responses to these treatments in the absence of additional environmental stress.

The uptake of cadmium and zinc by the bird-cherry oat aphid Rhopalosiphum padi (Homoptera:Aphididae) feeding on wheat grown on sewage sludge amended agricultural soil

A greenhouse trial investigated the uptake of cadmium and zinc by the bird-cherry oat aphid ( Rhopalosiphum padi) feeding on wheat grown on sewage sludge amended soil. The trial was conducted at application rates of 0, 5, 7.5, 10, 15 and 20 tonnes ha −1 dry solids. Concentrations of Cd and Zn were within current UK limits for potentially toxic elements in soils amended with sewage sludge. Cd and Zn in wheat plants were significantly greater than controls. Batches of aphids feeding on the wheat also showed a significant increase in the uptake of Cd and Zn. This study demonstrates a potential route of exposure to Cd and Zn for the predators of cereal aphids.

Effect of the systemic fungicide benomyl on the symbionts and mycetocytes of the bird cherry—oat aphid (Rhopalosiphum padi) (Homoptera: Aphididae) reared on wheat plants

AbstractOnly a few symbionts and mycetocytes in the bird cherry–oat aphidRhopalosiphum padi(Linnaeus) reared for three days were affected on plants treated with 50 ppm benomyl. The symbionts of aphids reared for the same time on plants treated with 100 ppm benomyl, however, were abnormal and at an early stage of degeneration. Mycetocytes contained more residual bodies than normal. The symbionts and mycetocytes of embryonic aphids on such plants were also abnormal. When aphids were reared for 3 days on plants treated with 200 ppm benomyl, the symbionts and mycetocytes were drastically affected. Most of the symbionts were very abnormal and had degenerated. The mycetocytes were full of electron-lucent and electron-dense structures intermixed with abnormal cell organelles. Symbionts and mycetocytes of embryonic aphids were abnormal. In contrast, when the systemic insecticide pirimicarb was used to kill aphids, it did not affect the symbionts and mycetocytes. When aphids were reared for 6 days on plants treated with 50 ppm benomyl, their symbionts and mycetocytes and those of their offspring were also degenerate and abnormal, as were those of Fl generation aphids from mothers reared from birth on plants treated with 50 ppm benomyl. From a consideration of the known mode of action of benomyl on tubulin and the presence of tubulin only in the mycetocyte cells, it is concluded that the degeneration of symbionts in benomyl-treated aphids is a secondary consequence of the degeneration of the aphid mycetocytes.

Effect of Imidacloprid on Nonflight Movement ofRhopalosiphum padiand the Subsequent Spread of Barley Yellow Dwarf Virus

The bird cherry-oat aphid (Rhopalosiphum padi) is an important vector of the barley yellow dwarf luteovirus, BYDV-PAV-IL. Insecticides used to reduce the abundance of the vector on small grains can result in an increase in aphid activity and a subsequent increase in disease incidence. The transmission characteristics of viruliferous wingless (nymphs and apterous adults) R. padi after access to oats treated with different rates of imidacloprid, a seed-treatment insecticide, were compared. After access to treated plants, aphid fecundity was reduced and aphids walked and fed atypically and often abandoned the host plant

Resistance to bird cherry-oat aphid (Rhopalosiphum padi L.) in winter wheat varieties

In Hungary the bird cherry-oat aphid (Rhopalosiphum padi L.) is the most frequent aphid species in winter wheat (Triticum aestivum L.). Estimations of infestation by R. padi as well as measurements of grain yield and thousand-kernel mass were carried out in 26 winter wheat genotypes in conditions of naturally infested and not infested (protected) control plots. The experiment was performed in isolated conditions in two field cages covered by nets. The aphids overwintered on wheat and got into cage, extremely quickly multiplied, therefore there was no need to apply any artificial aphid infestation. Highly significant differences were demonstrated among genotypes in infestation severity of R. padi as well as in losses of grain yield and thousand-kernel mass. The most resistant variety ‘GK Zombor’ had 25% infestation, and the most susceptible one ‘GK Lili’ had 79.2%. The reduction of grain yield of the most tolerant genotypes (‘GK Korany’, ‘Downy’, ‘Mv 4’, ‘Jubilejnaja 50’, ‘Mv 8’, ‘GK Kincso’ and ‘GK Zombor’) was 26–33%, and that of thousand-kernel mass was 23–30%. The most sensitive genotypes (‘GK Lili’, ‘GK Orzse’, ‘GK Koppany’ and ‘Mv 13’) suffered 58–63% losses in yield, and 40–50% in thousand-kernel mass. A close correlation was found between infestation of R. padi in different wheat genotypes and losses of grain yield (r=0.7572, P<0.001). Also there were tolerance differences among genotypes even within the same level of infestation. The reductions of thousand-kernel mass correlated very closely with the reductions of grain yield (r=0.9212, P<0.001), that makes screening possible by reductions of thousand-kernel mass. These results have found application in breeding. The leaf pubescence of the varieties studied did not generally influence the infestation by R. padi.

Spatial Distribution of Rhopalosiphum padi (L.) (Homoptera: Aphididae) in Spring Cereals in Sweden and its Importance for Sampling

The spatial distribution of the bird cherry-oat aphid Rhopalosiphum padi in spring cereals was analyzed using the negative binomial common k , Taylor's power law, and Iwao's regression technique. A common k could not be fitted to all data because of the large range in densities. Taylor's method was chosen instead of Iwao's because of problems with interpretation of the results. Using Taylor's regression coefficients, sequential count and sampling decision plans were developed. Their uses in the field for forecasting and monitoring for economic thresholds are discussed.

Aphid detection of endophyte infection in tall fescue

Abstract The bird-cherry oat aphid Rhopalosiphum padi L. avoided tall fescue (Festuca arundinacea Schreb.) plants infected with the endophyte Acremonium coenophialum Morgan-Jones & Gams but settled on tall fescue infected with a Phialophora-like endophyte and on endophyte-free plants. The presence of either Acremonium loliae Latch, Christensen & Samuels or a Gliocladium-like endophyte in perennial ryegrass (Lolium perenne L.), and of Epichloe cf. typhina (Pers.) Tul. in chewings fescue (Festuca rubra L. sens. lat.) did not affect the feeding preferences of R. padi compared with uninfected controls. A method of using R. padi for the detection of A. coenophialum in tall fescue is suggested.