Biochemical markers of oxidative stress in triticale seedlings exposed to cereal aphids

In this study, we examined whether and to what extent oxidative stress is induced in seedlings of two winter triti- cale (Triticosecale wittm.) varieties (susceptible Tornado and resistant witon) in response to infestation by the cereal grain aphid (sitobion avenae l.) and bird-cherry-oat aphid (rhopalosiphum padi l.). we compared the level of hydrogen peroxide (H 2O2) and lipid peroxidation products as well as markers of protein damage (protein- bound thiol and carbonyl groups). The studied parameters were measured at 6, 24, 48 and 96 h post-initial aphid infestation compared to the non-infested control seedlings. Our studies indicated that the cereal aphid feeding evoked oxidative stress in the triticale seedlings. Cereal aphid feeding increased the H2O2 level in triticale tissues, with maximum levels observed at 24 and 48 h post-infestation. Triticale infestation with aphids also increased lipid peroxidation products in triticale seedlings, with the maximal levels at 48 or 96 h post-infestation. Further, there was a reduction in protein thiol content and an increase in protein carbonyl content in the triticale seedlings after infestation with female aphids. Stronger triticale macromolecule damages were evoked by the oligophagous aphid r. padi. There was a more substantial protein thiol content reduction in the resistant witon cultivar and higher accumulation of protein-bound carbonyls in the tissues of the susceptible Tornado cultivar. The changes were proportional to the aphid population and the time of aphid attack. These findings indicate that the defensive strategies against cereal aphid (s. avenae and r. padi) infestation were stimulated in triticale Tornado and witon seedlings. Our results explain some aspects and broaden the current knowledge of regulatory mechanisms in plant-aphid interactions

Effect of plant o-dihydroxyphenols and quinone on generation of reactive oxygen species within the grain aphid tissues

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

Effect of host plants on biochemical markers of oxidative stress within tissues of Pea aphid

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

Relationship between saponin content in alfaalfa and aphid development

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

Effect of phenolics on the pea aphid, Acyrthosiphon pisum [Harris] population on Pisum sativum L. [Fabaceae]

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

Molecular evidence of Anaplasma phagocytophilum and Babesia microti co-infections in Ixodes ricinus ticks in central-eastern region of Poland

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