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The performance of the pea aphid, Acyrthosiphon pisum Harris (Homoptera: Aphididae) was studied on several Fabaceae species including: pea (Pisum sativum), broad bean (Vicia faba), alfalfa (Medicago sativa), bean (Phaseolus vulgaris) and red clover (Trifolium pratense). Alfalfa, bean and red clover were less accepted by the pea aphid than pea and broad bean. The pea aphid fed on the alfalfa, bean and red clover showed longer pre-reproductive, and shorter reproductive and post-reproductive periods. Alfalfa, bean and red clover also shortened and decreased fecundity of the pea aphid. Mean survival of the pea aphids fed on red clover and bean plants was reduced in comparison to pea aphid fed on pea and broad bean. The other studied population parameters: intrinsic rate of natural increase (rm), net reproduction (R0) and mean generation time were also reduced in the case of the pea aphid on alfalfa, red clover and bean. The study of aphid development and reproduction demonstrated that pea and broad bean are suitable host plants for A. pisum while alfalfa, red clover and bean are not. It is likely that the rejection of alfalfa, red clover and bean by A. pisum was caused by chemical factors in these hosts.
Effect of some dietary o-dihydroxyphenols and quinones on hydrogen peroxide (H2O2) concentration within tissues of the grain aphid Sitobion avenae (F.) (Homoptera, Aphididae) has been studied. Among the studied aphid morphs the highest level of H2O2 total was noted for winged adults (alatae) and the lowest for larvae. The aphids exposed to the dietary pro-oxidative o-dihydroxyphenols demonstrated significantly higher concentration of hydrogen peroxide than the control ones. Among the studied compounds, caffeic acid showed the strongest effect on the H2O2 level within the aphid tissues. The highest concentration (0.1%) of this phenolic acid caused above 2-fold increase in the content of this radical within the grain aphid tissues. The significance of these results for understanding the toxicity of phenols to cereal aphids is discussed.
The aim of the present study was to compare ascorbate (ASA) content and ascorbate peroxidase (APX) activity in seedlings of the less susceptible triticale cultivar Witon and the more susceptible triticale cultivar Tornado after infestation by the grain aphid Sitobion avenae (F). and the bird cherry-oat aphid Rhopalosiphum padi (L.). The content of ASA in triticale seedlings slightly decreased after 24 hrs of infestation by cereal aphids, but prolonged feeding (48 hrs and 72 hrs) resulted in significant losses in ASA dependent on cultivar and aphid species. The aphid infestation caused an increase in APX activity in triticale tissues throughout the test period. The aphid herbivores induced APX activity to a higher level in a less susceptible cultivar than in a more susceptible one. The oligophagous species R. padi caused a higher decrease of ASA and stronger induction of APX activity in tested triticale than the monophagous species S. avenae. The experiments carried out indicate that ascorbate and ascorbate peroxidase may play a significant role in the defense mechanism of aphid infested triticale.
Flavonoids play an important role in interactions of plants with the environment. Liquid chromatography (HPLC) was used to determine the flavonoid profiles (especially luteolin, tricin, and chrysoeriol glycosides), their total concentrations, and changes in the amounts of eight flavones found in the aerial parts of alfalfa (Medicago sativa L.) (Fabaceae) Radius cv., uninfested and infested by the pea aphid (Acyrthosiphon pisum Harris) (Homoptera: Aphididae). It was shown that both control and infested green aerial parts of alfalfa plants had similar flavonoid profiles. The dominant flavonoid of alfalfa was compound 7-O-[2-O-feruloyl-β-D-glucuronopyranosyl( 1→2)-O-β-D-glucuronopyranosyl]-4’-O-β-D-glucuronopyranosideluteolin. Compound 7-O-{2’-O-feruloyl-[β-D-glucuronopyranosyl(1→3)]-O-β-D- glucuronopyranosyl(1→2)-O-β-D- glucuronopyranosidetricin was present in the smallest amounts. The total concentration of flavones was rather high and ranged from 11.13 to 12.34 mg/g d.m., but there were no significant differences between uninfested and infested alfalfa plants. There was a correlation between the concentration of flavonoid glycosides in the alfalfa plants and pea aphid abundance. Pea aphid daily fecundity per female was affected by luteolin, tricin, and chrysoeriol glycosides and the level of chrysoeriol glycosides affected ingestion of xylem sap by the aphid. This finding may indicate that the studied flavonoid glycoside forms are biologically active in alfalfa – A. pisum interactions.
The effect of some species of the Fabaceae family (the pea Pisum sativum L., broad bean Vicia faba L. and vetch V. sativa L.) on biochemical markers of oxidative stress within tissues of the pea aphid, Acyrthosiphon pisum Harris (Homoptera, Aphididae), has been studied. The highest concentration of superoxide anion radical (O2-), hydrogen peroxide (H2O2) and lipid peroxidation products thiobarbituric acid reactive substances (TBARS) was recorded for morphs that fed on the broad bean. The opposite tendency was observed for the level of total thiols, that were the highest for insects reared on the pea. Among the studied aphid morphs, the highest concentration of superoxide anion and hydrogen peroxide was noted for the wingless females whereas TBARS content was the highest within the winged migrant tissues. Different results were obtained for the total thiols, where apterae as well as migrants reared on the tested plants, had comparable content of these compounds. Our experiments indicate that oxidative stress may play an important role in interactions between the pea aphid and their host plants.
Host specialization plays a central role in physiological diversification of aphids and plant-insect co-evolution. Different morphs of the bird cherry-oat aphid (Rhopalosiphum padi L.) are specialized and locally adapted to both primary and secondary hosts. The abundance of bird cherry-oat aphid population was estimated using the technique of direct counting of aphid individuals infesting 50 randomly selected, fully expanded 1-year side shoots of bird cherry (approx. 40 cm long) grown in the Municipal Park „Aleksanria” in Siedlce (central-eastern Poland). Entomological observations were conducted during three consecutive vegetation seasons: 2001–2003. The impact of R. padi feeding on composition of free amino acids within leaves of its primary host (the bird cherry, Prunus padus L.), infested and uninfested by aphids were studied. Eight essential amino acids (Val, Thr, Phe, Ileu, Leu, Met, His and Lys) and seven non-essential amino acids (Asp, Glu, Pro, Ser, Ala, Gly and Tyr) were identified in the bird cherry-oat leaves with the use of highperformance liquid chromatography (HPLC) separation. There were quantitative differences in free amino acids content between the tested bird cherry-oat leaves (infested and uninfested by aphids). Levels of the free amino acids were decreased in leaves attacked by R. padi, and detailed analyses revealed about 20% decline in the content of studied components during maximal aphid abundance in comparison with non-infested leaves. Additionally, the feeding behavior of the bird cherry-oat aphid seasonal morphs (fundatrix, fundatrigeniae, alatae) on the primary host was investigated. Using the electrical penetration graph (EPG) we showed differences in feeding behavior of bird cherry-oat aphid morphs on primary host. The total probing time was greatest for fundatrigeniae among all studied morphs. These individuals spent more time during phloem sap ingestion then others. Adults of alatae were not active in the phloem sap ingestion on the bird cherry. Among the tested morphs xylem sap ingestion activity was greatest for alatae. It is hypothesized that rejection of primary host and subsequent the bird cherry-oat aphid migration onto secondary hosts may be stimulated by the decline in levels of free amino acids within primary host leaves caused by long-term R. padi feeding. Comparative analyses of the aphid probing behavior additionally proved that P. padus leaves possessed high nutritive value of food for non-winged morphs (early stages of aphid infestation), while not sufficient for winged alatae (terminal phase of infestation).
Extensive studies have been carried out to identify plant phenolics with insecticidal properties towards insects. The subject of the study were comparison of control and infested by Acyrthosiphon pisum (Harris) vegetative parts of pea plants. In the pea plants six flavonol aglycones were identified: quercetin, kaempferol+RCO-, kaempferol, tricin, apigenin+RCO-, and apigenin. In infested plants relatively high concentration of total phenols, o-dihydroxyphenols and total flavonoids in comparison with control were observed. It suggests that phenolics have negative effect on insects and they are good for control of the insect pests.
We studied the effect of qualitative and quantitative variation of saponin content in foliar tissues of four European alfalfa (Medicago sativa L.) cultivars (Radius, Sapko, Sitel, Radius line 1) on pea aphid (Acyrthosiphon pisum Harris) development, and the effect of aphid infestation on alfalfa saponin content. Aphids (adult apterae, larvae, and adult alatae) were counted on 3-, 6- and 9-month-old plants (before the first, second and third cutting). Thin-layer chromatography was used to detect and estimate the quantity of the following saponins: 3GlcA, 28AraRhaXyl medicagenic acid; 3Glc, 23Ara, 28AraRhaXylApi zanhic acid (zanhic acid tridesmoside); and 3RhaGalGlcA soyasapogenol B (soyasaponin I). Radius, Sapko, and Sitel contained all three saponins but Radius line 1 did not contain zanhic acid tridesmoside or medicagenic acid glycoside. Saponin content was highest in Radius and lowest in Radius line 1. Regardless of the cultivar, saponin content was higher in aphid-infested than uninfested plants. For all sampling dates, aphid numbers were highest on Radius line 1 and lowest on Radius; that is, aphid numbers were inversely related to saponin content. Alfalfa has a herbivoreinduced defense. Saponin levels increase in the foliage of infested alfalfa. Attempts of plant breeders to reduce saponin content in order to increase alfalfa digestibility for livestock might make the plants more susceptible to aphids and other pests.
The purpose of the research was to assess the number of aphids in two different winter triticale genotypes. The effect of winter triticale genotypes mixtures was determined on the base of aphids’ number and percentage of infested plants. Field observations were performed on IHAR Radzików experimental plots in two seasons (2008 and 2009). The results presented here suggested that the aphid number and number of infested plants in mixture were lower than in pure stands. Waxy genotype (RAH 116−3/90) was more resistant to the cereal aphids than the wax-less genotype RAH 325/95. In addition, Sitobion avenae showed a higher level of studied population parameters then Rhopalosiphum padi on the triticale genotypes.
Flavonoids are a group of secondary metabolites found in most families. They are known to have important physiological functions in plants by protecting them against biotic stresses. Liquid chromatography (HPLC) was used to determine the flavonoid profiles, especially apigenin glycosides, their total concentration, as well as changes in the amount of six flavones found in the aerial parts of alfalfa (Medicago sativa L.) (Fabaceae) Radius cv. for three vegetative stages, uninfested and infested by the pea aphid (Acyrthosiphon pisum Harris) (Homoptera: Aphididae). It has been shown that both control and infested green aerial parts of alfalfa plants had similar flavonoid profiles. The dominant flavonoid of alfalfa was compound 7-O-[2-O-feruloyl- β-D-glucuronopyranosyl(1→2)-O-β-D-glucuronopyranosyl]-4’-O-β-D-glucuronopyranosideapigenin. Compound 4’-O-β-D-glucuronopyranosideapigenin was present in the smallest amounts. The total concentration of flavones was rather high and ranged from 10.32 to 12.28 mg/g d.m., but there were no significant differences between uninfested and infested alfalfa plants. There was a negative correlation between the concentration of total apigenin glycosides in the alfalfa plants and pea aphid abundance and phloem sap ingestion. This finding may indicate the importance of apigenin glycoside forms as nutritional compounds.
The purpose of performed analyses was to study the impact of Rhopalosiphum padi L. infestation on the level of ribonucleolytic activity in bird cherry leaves during three consecutive vegetation seasons (2003–2005). It was shown that feeding of the bird cherry-oat aphid on P. padus leaves stimulated the activity of acid and alkaline ribonucleases when compared to control (without aphids). Furthermore, the highest rise in activity of both groups of RNases was recorded during increasing and maximal density of aphid population on its primary host shoots.
The aim of the study was to elucidate the distribution of Anaplasma phagocytophilum and Babesia microti co-infection in Ixodes ricinus populations within the central-eastern region of Poland. The prevalence of analysed tick-borne human pathogens in single and polymicrobial infections in I. ricinus ticks were analysed using the conventional and nested PCR techniques. A total number of 1,123 questing tick individuals (291 females, 267 males and 565 nymphs) were collected at different ecosystems (municipal parks, suburban forests, and woodlands). In the presented study, 95 samples of ticks (8.5%) were infected with A. phagocytophilum, 3.1% (n=35) with B. microti, whereas the co-existence status of these human pathogens was detected in 1.8% (n=20) of all tested samples. It has been demonstrated that the prevalence of co-infection status was the highest among females of I. ricinus (11 samples, 3.8%), whereas the lowest within tested nymphs (5 samples, 0.9%). Ticks collected at city parks in Warsaw and suburban areas of this town characterized the highest prevalence of co-infections (3.3 and 4.8%, respectively). Furthermore, it was established that co-infection rates of ticks inhabiting woodlands within Kampinos National Park and Nadbużański Landscape Park were similar and reached the levels of 1.4% (n=5) and 1.1% (n=4), respectively.
Juglone (JU; 5-hydroxy-1,4-naphthoquinone) is an allelochemical synthetized by a wide range of Juglandaceae members. This compound evokes a wide array of detrimental effects in susceptible acceptor plants, including growth inhibition and impairments in the course of biochemical and physiological processes. Therefore, juglone may be considered as a potential bioherbicide in weed control in cereal crops. The purpose of our study was to determine the influence of JU treatment on the content of superoxide anion radical (O2•−) - sensitive and early marker of oxidative stress, and the activity of superoxide dismutase (SOD) - enzyme that functions as a crucial component of the first line antioxidative defense in seed tissues. In the study we tested seeds of four selected plant species of cereal agrosystem: corn poppy (Papaver rhoeas L.), corn cockle (Agrostemma githago L.), spring wheat (Triticum aestivum L., cv. Nawra), and spring oat (Avena sativa L., cv. Maczo). Additionally, the allelopathic influence of JU on seed germination of the studied plant species was investigated. The seeds were exposed to three examined juglone concentrations: 0.001, 0.1, and 10 mM (4% methanoldeionized water solutions), whereas the control seeds were treated with aqueous methanolic solutions (4%). Obtained results evidenced much more severe suppression of germination process and robust generation of superoxide anion radical in the tested weeds, compared to the cereals, and the crucial role of superoxide dismutase in limiting the juglone-induced oxidative stress in the studied seeds.
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