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BACKGROUND Colorado potato beetle ( CPB) has become the biggest enemy of cultivated potato worldwide. One of the most effective sources of resistance to CPB is Solanum chacoense, an accession with a high leptine glycoalkaloid content. The aim of our study was to assay the repellence and toxicity of S. chacoense, its somatic hybrids ( SHs) and their backcross progenies ( BC1) with potato for CPB adults and larvae. Transgenic S. chacoense, deficient in DNA mismatch repair ( MMR), was also used to produce SHs, in order to increase homeologous recombination and hence introgression of wild-species DNA into the potato gene pool. RESULTS Wild-type SH was highly resistant to CPB. Resistance to CPB of BC1 progenies showed a 1:3 inheritance pattern. MMR-deficient SHs performed better in the resistance analysis. Most MMR-deficient SHs had a similar toxicity as S. chacoense and an intensely repellent effect on CPB adults. Resistance of SHs and BC1 clones may be attributed to leptine biosynthesis, which was confirmed using a RAPD marker. CONCLUSION This is the first report of SHs and their progenies exhibiting both antibiosis and antixenosis against CPB. Resistant SHs are an important step forward in combating this voracious pest of potato. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

1. Maternal and offspring diet effects on life-history traits of the bird cherry-oat aphid Rhopalosiphum padi were tested on three wheat varieties. Using nine reciprocal combinations of wheat varieties, the effects of previous experience (maternal diet effect) on the aphid's response to resistant and susceptible varieties (offspring diet effect) were tested. Batis was susceptible, and Xiaoyan22 and Ww2730 were both resistant, but with different mechanisms. 2. Aphids produced the most alatae in the treatments with the most resistant maternal diet variety Xiaoyan22. The fecundity ( F) and intrinsic rate of increase ( rm) of these alatae were at their greatest in the most resistant offspring diet variety, but these traits were not influenced in the apterae. 3. There were significant interactions in the alatae production and apterae life-history traits, such as rm, development time, weight gain, and mean relative growth rate, between the maternal and offspring diet varieties. The interactions in apterae responses between varieties, some of which were reciprocal, indicated phenotypic plasticity in these parthenogenetic aphids. 4. Rhopalosiphum padi produced more alatae on the most resistant variety; the alatae would disperse and were more fecund. The growth responses of the apterae showed phenotypic plasticity to the different combinations of maternal and offspring diet varieties. The phenotypic plasticity would allow R. padi to better utilise the variable environments represented by the small wheat plots of different varieties in China. [ABSTRACT FROM AUTHOR]

1 Previous feeding by herbivores may influence the performance of other herbivores by altering the morphological and physiological properties of the shared host. 2 The present study aimed to examine the fitness of the apterous aphid Sitobion avenae (Fabricius) (Hemiptera: Aphididae) when fed spring wheat that was previously attacked by the leafhopper Psammotettix alienus Dahlbom (Hemiptera: Cicadellidae), with an evaluation of the differences in aphid weight (WD), development time (D), mean relative growth rate (MRGR), daily production of nymphs (MDNP) and intrinsic rate of population increase (rm) under controlled greenhouse conditions. 3 For the S. avenae reared on the two spring wheat cultivars that were previously infested with P. alienus, the WD and the MRGR decreased significantly. The S. avenae reared on the previously infested cv. Leguan had significantly prolonged D values and a lowered rm, whereas these parameters did not differ significantly when S. avenae was reared on the cv. Bobwhite. 4 Overall, the fitness of the aphid S. avenae was adversely affected when reared on the two spring wheat cultivars that were previously infested with P. alienus. [ABSTRACT FROM AUTHOR]

Eight isolates from different potato growing regions in Vietnam were characterized. All were highly pathogenic in some potato cultivars, but did not overcome the extreme resistance of Solanum stoloniferum and Solanum demissum. RT-PCR analysis revealed that all of these isolates are recombinants. Sequence data for 4 isolates were obtained, and their reaction in potato cultivars harbouring specific N genes was determined. Different phylogenetic analyses of viral sequences confirmed previous results that the recombinant isolates evolved from different parental sequences. One of the Vietnamese isolates investigated had a specific structure. The need for a clear classification of PVYNWi isolates is discussed. [ABSTRACT FROM AUTHOR]

Life tables of brown and green color morphs of the English grain aphid, Sitobion avenae (Fabricius) reared on barley under laboratory conditions at 20 ± 1°C, 65% ± 5% relative humidity and a photoperiod of 16 : 8 h (L : D) were compared. The plants were either: (i) infected with the Barley yellow dwarf virus (BYDV); (ii) not infected with virus but previously infested with aphids; or (iii) healthy barley plants, which were not previously infested with aphids. Generally, both color morphs of S. avenae performed significantly better when fed on BYDV-infected plants than on plants that were virus free but had either not been or had been previously infested with aphids. Furthermore, when fed on BYDV-infected plants, green S. avenae developed significantly faster and had a significantly shorter reproductive period than the brown color morph. There were no significant differences in this respect between the two color morphs of S. avenae when they were reared on virus-free plants that either had been or not been previously infested with aphids. These results indicate that barley infected with BYDV is a more favorable host plant than uninfected barley for both the color morphs of S. avenae tested, particularly the green color morph. [ABSTRACT FROM AUTHOR]

The effects of enhanced UV-B radiation on the biology of green and brown morphs of Sitobion avenae (F.) (Hemiptera: Aphididae) were tested under laboratory conditions. The two S. avenae morphs were exposed directly to different doses (0, 216 432, and 864 kJ/m² of artificial UV-B. Under low doses of UV-B (216 kJ/m²), the nymphal development period was significantly shorter, whereas mean relative growth, total fecundity, and gross reproductive rate were significantly higher for both aphid morphs compared with those morphs under control treatments (0 kJ/m²). Under high doses of UV-B (432 kJ/m² and/or 864 kJ/m²), the nymphal development period was significantly longer, whereas the reproductive period, postreproductive period, difference in weight, mean relative growth, and life table parameters were significantly reduced for both aphid morphs. Moreover, the nymphal development period was significantly shorter and the differences in weight, mean relative growth, total fecundity, and life table parameters were significantly higher for the brown morph under high doses of UV-B compared with the green morph. The results showed that enhanced UV-B affects the performance of the green and brown S. avenae morphs from positively to negatively. The brown morph exhibited stronger adaptability than the green morph at high doses of UV-B. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study that investigated the feeding behavior of the English grain aphid Sitobion avenae, a non-vector of Wheat dwarf virus (WDV) and Cereal yellow dwarf virus-RPV (CYDV-RPV), on virus-infected host plants, Hordeum vulgare. The Sitobion avenae on infected plants showed reduced non-probing and pathway phase. No differences in aphid feeding behavior on virus-free and vector pre-infested plants were observed.

Solanum tarnii, a wild diploid, tuber-bearing Mexican species belonging to the series Pinnatisecta is highly resistant to Potato virus Y (PVY) and Colorado potato beetle and shows a strong hypersensitive reaction to Phytophthora infestans. Therefore, it could be a potential source of resistance to pathogens for potato breeders. S. tarnii (2 n = 2 x = 24) is reproductively isolated from tetraploid Solanum tuberosum and hence difficult to include in potato breeding programmes. In this study, interspecific somatic hybrids were produced for the first time by protoplast electrofusion of the cells of potato cv. Delikat ( Solanum tuberosum L.) and Solanum tarnii. The hybrid nature of the regenerants was confirmed by simple sequence repeat (SSR) and amplified fragment length polymorphism (AFLP) markers and by morphological analysis and flow cytometry. Selected somatic hybrids were successfully backcrossed with cv. Delikat. Parental lines, primary somatic hybrids and BC1 progeny were assessed for resistance to PVY by mechanical inoculation, grafting and exposure to viruliferous aphid vectors in the field, and resistance to late blight ( P. infestans) by detached leaflet and whole tuber tests. The somatic hybrids showed no symptoms of viral infection and most of them displayed high levels of resistance to foliage blight. The BC1 progenies were highly resistant to PVY and a few were resistant to foliage blight. Selected hybrids and BC1 clones were evaluated in the field for tuber quality and tuber yield. Some BC1 clones produced yields of good quality tubers. The results confirm that both the resistance to PVY and to late blight of S. tarnii is expressed in somatic hybrids, and PVY resistance is transferred to BC1 progeny, whereas blight resistance is harder to transfer. Somatic hybridization again proved to be a valuable tool for producing pre-breeding material with increased genetic diversity. [ABSTRACT FROM AUTHOR]

The wild non-tuberous species Solanum etuberosum is resistant to biotic and abiotic stresses, but is very difficult to cross with cultivated potato. Therefore, interspecific somatic hybrids between a dihaploid clone of potato S. tuberosum (2n=2x=24, AA genome) and the diploid species S. etuberosum (2n=2x=24, EE genome) were produced by protoplast fusion. Among the 7 fertile fusion hybrids analysed by genomic in situ hybridisation (GISH), three groups of plants were found with the genomic constitution of AAEE, AAEEEE and AAAAEE. Four fusion hybrids had exactly the expected chromosome composition, while each of the three aneuploid hybrids had lost two chromosomes of S. etuberosum. Two backcross progenies were developed, and GISH analysis was applied to analyse transmission of the parental chromosomes into the sexual generations. BC1 hybrids derived from the crosses of the hexaploid somatic hybrids with tetraploid potato were pentaploid with the theoretically expected genomic composition or with slight deviation from this expectation. In the three BC2 hybrids analysed by GISH seven to 12 chromosomes of S. etuberosum were detected in the predominant S. tuberosum background. No recombinant chromosomes in the hybrids were detected. Genome dosage affects tuber formation in hybrids and their progenies, but has less effect on resistance to potato virus Y (PVY) in fusion hybrids. Several genotypes of the fusion hybrids and BC1 progeny did not show viral infection even in the grafting experiments. [ABSTRACT FROM AUTHOR]

Objectives: To assess the efficacy of oral fluid antibody testing for the detection of hepatitis C. Methods: Paired serum and oral fluid collections were obtained from 216 subjects. A modification of the serum HCV ELISA assay was developed to improve test accuracy for an oral fluid substrate. Sensitivity was determined in 109 HCV serum ELISA-positive patients and specificity in 107 HCV serum ELISA-negative patients. Results: Overall sensitivity of oral fluid collection and testing was 98.2%; specificity was 99.1%. These parameters did not seem to be altered by presence of concurrent hepatitis B infection, inflammatory state of the liver, or other factors. Conclusions: Oral fluid collection and HCV antibody testing by the modified ELISA method seems to be an effective and efficient alternatives to venipuncture and serum HCV antibody testing. Their use may facilitate epidemiological surveys and evaluation of individual patients when blood collection is not feasible. [ABSTRACT FROM AUTHOR]

UV-B induced changes in plants can influence sap-feeding insects through mechanisms that have not been studied. Herein the grain aphid, Sitobion avenae (Fabricius) (Hemiptera: Aphididae), was monitored on barley plants under the treatments of control [0 kJ/ (m2.d)], ambient UV-B [60 kJ/ (m2.d)], and enhanced UV-B [120 kJ/ (m2.d)] irradiation. Electrical penetration graph (EPG) techniques were used to record aphid probing behaviors. Enhanced UV-B irradiated plants negatively affected probing behaviors of S. avenae compared with control plants. In particular, phloem factors that could diminish sieve element acceptance appeared to be involved, as reflected by smaller number of phloem phase, shorter phloem ingestion, and fewer aphids reaching the sustained phloem ingestion phase (E2>10min). On the other hand, factors from leaf surface, epidermis, and mesophyll cannot be excluded, as reflected by higher number of non-probing, longer non-probing and pathway phase, and later the time to first probe.