Noncrop Host Plant Associations for Oversummering of Diuraphis noxia in the State of South Australia.

Diuraphis noxia, Russian wheat aphid (Hemiptera: Aphididae), established in Australia since 2016, is dependent on grasses (Poales: Poaceae) to persist in the low-rainfall Australian wheat belt, where no crops are present during summer. To identify grasses as D. noxia hosts in Australia, plants were tested in greenhouse conditions as either whole plants collected from roadsides or grown from collected seed in 2017 and 2018. To determine actual field refugia, direct grass sampling and Berlese extraction of aphids were conducted from October 2018 to May 2020 throughout Southern Australia (2,285 samples). One hundred and twenty-six grass species were collected, 54 showed presence of D. noxia, of which 24 were considered host plants, including 16 species (9 Australian natives) not recorded as host plants previously. Hordeum leporinum (Link) Arcang. Poales:Poaceae and several Bromus species (Poales: Poaceae) showed the highest D. noxia detection frequency and aphid numbers, but these introduced grass species are not summer active in most of South Australia. The native Enneapogon nigricans (Poales: Poaceae) (R.Br.) is the most important summer refuge species because of its widespread distribution, summer growth, and an intermediate level of positive detections with low D. noxia populations. The late summer represents the main bottleneck for D. noxia with very few hosts available and very low D. noxia detections overall. Late summer rainfall (February) seems essential to have the main host grasses germinate for D. noxia populations to build up and potentially invade crops sown in autumn.

The potential distribution of the Russian wheat aphid (Diuraphis noxia): an updated distribution model including irrigation improves model fit for predicting potential spread.

Diuraphis noxia (Kurdjumov), Russian wheat aphid, is one of the world's most invasive and economically important agricultural pests of wheat and barley. In May 2016, it was found for the first time in Australia, with further sampling confirming it was widespread throughout south-eastern regions. Russian wheat aphid is not yet present in New Zealand. The impacts of this pest if it establishes in New Zealand, could result in serious control problems in wheat- and barley-growing regions. To evaluate whether D. noxia could establish populations in New Zealand we used the climate modelling software CLIMEX to locate where potential viable populations might occur. We re-parameterised the existing CLIMEX model by Hughes and Maywald (1990) by improving the model fit using currently known distribution records of D. noxia, and we also considered the role of irrigation into the potential spread of this invasive insect. The updated model now fits the current known distribution better than the previous Hughes and Maywald CLIMEX model, particularly in temperate and Mediterranean areas in Australia and Europe; and in more semi-arid areas in north-western China and Middle Eastern countries. Our model also highlights new climatically suitable areas for the establishment of D. noxia, not previously reported, including parts of France, the UK and New Zealand. Our results suggest that, when suitable host plants are present, Russian wheat aphid could establish in these regions. The new CLIMEX projections in the present study are useful tools to inform risk assessments and target surveillance and monitoring efforts for identifying susceptible areas to invasion by Russian wheat aphid.

Living kidney transplantation in adult patients with atypical haemolytic uraemic syndrome.

BACKGROUND: Dysregulation of complement activation is the most common cause of the atypical haemolytic uraemic syndrome (aHUS). Many patients with aHUS develop end-stage renal disease and consider kidney transplantation. However, the recurrence rate after transplantation ranges from 45-90% in patients with known abnormalities in circulating complement proteins. It was recently proposed that patients with aHUS should be treated prophylactically with plasma exchange or eculizumab to prevent recurrence after transplantation. METHODS: A case series describing the successful outcome of kidney transplantation without prophylactic therapy in four adult patients with aHUS and a high risk of disease recurrence. Patients received a living donor kidney and immunosuppression consisting of basiliximab induction, low-dose tacrolimus, prednisone and mycophenolate mofetil. Patients received a statin, and were targeted to a low blood pressure preferably using blockers of the renin-angiotensin system. RESULTS: After a follow-up of 16-21 months, none of the patients developed recurrent aHUS. Also, no rejection was observed. CONCLUSIONS: Kidney transplantation in adult patients with aHUS can be successful without prophylactic eculizumab, using a protocol that minimises cold ischaemia time, reduces the risk of rejection and provides endothelial protection. Our data suggest that in patients with aHUS, controlled trials are needed to demonstrate the optimal strategy.

Comparing the spatial genetic structures of the Flavescence dorée phytoplasma and its leafhopper vector Scaphoideus titanus.

The Nearctic leafhopper Scaphoideus titanus Ball is the vector of "Flavescence dorée" phytoplasma (FDp) in European vineyards. We studied the genetic diversity and structure of S. titanus populations in France and of the FDp they carried. A total of 621 S. titanus individuals, sampled in 24 FDp-infected and uninfected vineyards, were genotyped using seven polymorphic microsatellite loci. The mean observed heterozygosity in S. titanus populations was between 0.364 and 0.548. There was evidence of only a low level of population genetic differentiation (mean F(ST)=0.027) suggesting that there is long-distance gene flow between S. titanus populations. This may be a consequence of the high migration capacity of the vector associated with large effective population size and, at least in part, of passive dispersion over long distances by the transport of grapevine-planting material carrying eggs. For each insect, FDp was detected and typed by nested-PCR followed by RFLP and sequencing of a 674 bp fragment of the FDp map gene. Twelve of the 24 populations were found to be infected by FDp, with the percentage of infected individuals varying from 3% to 29%. FDp isolates were classified into two FDp genetic clusters (FD1 and FD2), which differed by 12-13 SNPs. FD1 genotypes were detected in the insect populations at two sites and the FD2 genotypes in the other ten populations. Both FD1 and FD2 genotypes were found to be transmitted by the insect. No significant relationship was found between the genetic structure of these French S. titanus populations and the distribution of the various FDp strain types they carried. Nevertheless, overall genetic differentiation between FDp-infected and healthy S. titanus "subsamples" was found to be significantly higher than zero. These results suggest that FDp-infected S. titanus individuals are more philopatric (disperse less) than healthy S. titanus.

Isolation and characterization of polymorphic microsatellite loci in the green leafhopper Empoasca vitis Goethe (Homoptera).

Eight dinucleotide microsatellite loci were isolated and characterized within the green leafhopper Empoasca vitis (Goethe) using an enrichment cloning procedure. Primers were tested on 171 individuals collected in the southwest of France from the vine plants. The identified loci were polymorphic, with allelic diversity ranging from two to 18 alleles per locus. Observed heterozygosities were from 0.021 to 0.760. These microsatellite markers should prove to be a useful tool for estimating the population genetic structure, host-plant specialization and migration capacity of this insect.

Spatial distribution of the dagger nematode Xiphinema index and its associated Grapevine fanleaf virus in French vineyard.

The nematode Xiphinema index is, economically, the major virus vector in viticulture, transmitting specifically the Grapevine fanleaf virus (GFLV), the most severe grapevine virus disease worldwide. Increased knowledge of the spatial distribution of this nematode, both horizontally and vertically, and of correlative GFLV plant infections, is essential to efficiently control the disease. In two infested blocks of the Bordeaux vineyard, vertical distribution data showed that the highest numbers of individuals occurred at 40 to 110 cm depth, corresponding to the two layers where the highest densities of fine roots were observed. Horizontal distribution based on a 10 x 15 m grid sampling procedure revealed a significant aggregative pattern but no significant neighborhood structure of nematode densities. At a finer scale ( approximately 2 x 2 m), nematode sampling performed in a third block confirmed a significant aggregative pattern, with patches of 6 to 8 m diameter, together with a significant neighborhood structure of nematode densities, thus identifying the relevant sampling scale to describe the nematode distribution. Nematode patches correlate significantly with those of GFLV-infected grapevine plants. Finally, nematode and virus spread were shown to extend preferentially parallel to vine rows, probably due to tillage during mechanical weeding.

Ankle edema formation during treatment with the calcium channel blockers lacidipine and amlodipine: a single-centre study.

All studies suggesting a lower incidence of edema on lacidipine than on amlodipine are based on subjective scoring. Therefore, we have compared edema formation on two dihydropyridine calcium channel blockers, using an accurate method for quantitative assessment of foot volume. In a randomized study, we treated 62 patients with essential hypertension for 12 weeks starting with either lacidipine 4 mg o.d. (n = 30) or amlodipine 5 mg o.d. (n = 32). At 6 weeks, the doses were increased to that maximally allowed (lacidipine 6 mg, n = 18; amlodipine 10 mg, n = 12) if trough diastolic blood pressure response was insufficient (>90 mmHg and decrease < 10 mmHg). Edema, scored visually, occurred more frequently (p = 0.02) on amlodipine (15/32) than on lacidipine (6/30); this was confirmed by an increase of foot volume above the 95% upper limit of normal variation in 15 patients on amlodipine and in only five patients on lacidipine (p = 0.01). In the whole group of patients, both the increases of foot volume and the decreases of blood pressure just failed to be significantly different between amlodipine and ]acidipine (foot volume, +3.3+/-1.0% on amlodipine and +1.2+/-0.5% on lacidipine, p = 0.08; mean arterial pressure, -11+/-1% on amlodipine and -8+/-1% on lacidipine, p = 0.052). In patients requiring dose increase, the increase of foot volume on amlodipine was more pronounced (p < 0.05), and the antihypertensive effect was larger (p < 0.05) than on lacidipine. In conclusion, our data show a higher incidence of edema on amlodipine than on lacidipine, which has to be explained at least partly by a comparably higher dose c.q. a larger antihypertensive effect of amlodipine. Other mechanisms might have contributed to these differences and need to be explored.

The influence of lactate, pyruvate and glucose as exogenous substrates on free radical defense mechanisms in isolated rat hearts during ischaemia and reperfusion.

Previous studies have shown that exogenous lactate impairs mechanical function of reperfused ischaemic hearts, while pyruvate improves post-ischaemic recovery. The aim of this study was to investigate whether the diverging influence of exogenous lactate and pyruvate on functional recovery can be explained by an effect of the exogenous substrates on endogenous protecting mechanisms against oxygen-derived free radicals. Isolated working rat hearts were perfused by a Krebs-Henseleit bicarbonate buffer containing glucose (5 mM) as basal substrate and either lactate (5 mM) or pyruvate (5 mM) as cosubstrate. In hearts perfused with glucose as sole substrate the activity of glutathione reductase was decreased by 32% during 30 min of ischaemia (p < 0.10 versus control value), while the activity of superoxide dismutase and catalase was reduced by 27 and 35%, respectively, during 5 min of reperfusion (p < 0.10 versus control value). The GSH level in the glucose group was reduced by 29% following 30 min of ischaemia and 35 min of reperfusion (p < 0.10). In lactate- and pyruvateperfused hearts there were no significant decreases of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase activity during 30 min of ischaemia, 5 min of reperfusion or 35 min of reperfusion. In pyruvate-perfused hearts the glutathione peroxidase activity was even increased by 43% during 30 min of ischaemia (p < 0.05). Glutathione levels (reduced and oxidized) did not markedly change in the lactate and pyruvate groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of a bioassay to test phloem sap samples from lettuce for resistance toNasonovia ribisnigri (homoptera, aphididae).

TheNr-gene-based resistance of lettuce to the aphidNasonovia ribisnigri (Mosley) has previously been shown to be located in the phloem. Since chemical analyses of the phloem sap had shown no differences between resistant and susceptible lines, a bioassay was developed in order to test samples from resistant and susceptible plants on aphid feeding. For this, whole-plant extracts, honeydew, and EDTA-collected phloem extracts were obtained, and a sensitive bioassay was developed using EDTA samples. The EDTA was removed, and samples were added to a simple sucrose solution or to a complex artificial diet and presented in a choice situation comparing extracts from resistant and susceptible plants. EDTA-collected phloem sap samples from susceptible plants were preferred to those from resistant plants. The resistance is probably based on a feeding deterrent activity of the phloem sap in the resistant plant.

Phloem sap collection from lettuce (Lactuca sativa L.): Methodology and yield.

Three methods to collect phloem sap on different lettuce lines were optimized and are described in detail. The success ratio for stylectomy of aphids was over 80% through the combination of a specially designed setup and electrical penetration graphs to monitor phloem sap ingestion. For unknown reasons on some lettuce lines stylets never showed sustained exudation. There were clear differences in stylet exudation between two aphid species on the same lettuce line. Honeydew collection in hexadecane made accurate quantitative analysis possible; samples were large and clean, but biotransformed. The EDTA chelation method produced large samples, but dilution, oxidation, and impurities from the wound surface reduced the reliability.

Phloem sap collection from lettuce (Lactuca sativa L.): Chemical comparison among collection methods.

The chemical composition of phloem sap from lettuce, collected by three different methods, was compared. Phloem sap from stylectomy samples contained sucrose and 14 amino acids. Honeydew and EDTA chelation samples showed considerable breakdown of sucrose into fructose and glucose, several additional amino acids, and large differences in relative concentrations of amino acids, when compared to stylectomy samples. Honeydew contained considerable amounts of other oligosaccharides, and few proteins in low amounts, while EDTA showed many proteins. HPLC chromatograms showed numerous unidentified secondary plant compounds in honeydew and EDTA samples. Comparison of phloem sap samples from near-isogenic susceptible and resistant lines showed no relation of phloem sap composition with monogenic resistance to the aphidNasonovia ribisnigri.