The seasonal response of Italian and hybrid ryegrasses to the control of frit fly, Oscinella frit

In years of relatively high frit fly activity the control of all generations produced increases averaging 0×44 t d.m. ha^-1 in annual yield of Italian and hybrid ryegrass. A cutting programme designed to make the sward especially vulnerable to frit fly attack did not increase the total annual effect of pesticide treatment but accentuated the periods at which damage occurred. The annual yield increase was almost entirely obtainable by controlling the second and third frit fly generations, but even one treatment for this purpose was of doubtful economic justification. The prospect of augmenting the response to control of later-occurring pests, such as leatherjackets or eriophyid mites, by including the part of the frit fly response which is recoverable by the same treatment, was a more probable justification for pesticide usage. There was some evidence that a Westerwold and a hybrid cultivar suffered more damage than an Italian ryegrass cultivar, but pesticide treatment did not improve the persistence of any cultivar.     

The effect of frit fly (Oscinella frit) control measures on the establishment of seedling ryegrass (Lolium spp.)

In four experiments from 1981 to 1983 August-sown perennial (Lolium perenne) and Italian (L. multiflorum) ryegrass were exposed to frit fly attack by oviposition on the seedlings. Responses to pesticide treatment were detected at autumn harvests. Even at low sowing rates pesticide application did not ultimately establish a better sward and, owing to a tendency towards spring reversal of autumn yield responses, even temporary returns were negligible. As frit fly numbers were unusually low the autumn response to pesticide was sufficient to suggest that frit fly is always likely to be an influential factor in ryegrass sown in early August in this area. Later sowings are less likely to be affected. The yield response was related to the numbers of adult flies present 2–7 wk after sowing. Neither grass species was consistently more affected than the other. Additional seed (compared with a sowing rate below normal commercial rates) and the inclusion of fertiliser at sowing also gave only small temporary returns and failed to establish a better sward. It is suggested that routine protection against frit fly attack is of at least equal value to the other two variables in an early August sowing.     

Herbicide spray and frit fly attack on oats

Zusammenfassung Am 11. April gesäter Hafer (Sun II und Eagle) wurde am 12. Mai mit dem Herbizid CMPP gespritzt, zu einer Zeit, als Fritfliegen im Bestand vorhanden waren. Das Herbizid hatte keine Wirkung auf das Verhalten oder die Sterblichkeit der Fritfliegen.     

Numbers of mononchid nematodes in soils sown to cereals and grasses

The distribution of mononchid nematodes Mylonchulus sigmaturus, Mylonchulus brachyuris, Clarkus papillatus, Prionchulus punctatus and Anatonchus tridentatus found in grassland and arable soils in England were studied. Mononchid nematode populations in excess of 5% of the total soil nematode population and in biomass more than 2% of the total soil nematode population were rare. No relationship was found between numbers of mononchids and those of other soil nematodes. In soils sown to spring barley there was no difference in the total numbers of female M. sigmaturus, C. papillatus or A. tridentatus found throughout the year. Juveniles of C. papillatus were most common while those of M. sigmaturus were least common. In grass leys and arable soil P. punctatus numbers were extremely low. Neither phorate nor oxamyl applied at 1.12 kg a.i./ha in March affected mononchid numbers. Although oxamyl at 11.2 kg a.i./ha did not affect the adult female numbers, the numbers of juvenile mononchids were reduced by 38% and 50% in June and November respectively.     

The effect of frit fly Oscinella frit on the yield and persistence of Italian and hybrid ryegrasses in the laboratory

Three cultivars of Italian or hybrid ryegrass were exposed to frit fly attack at varying frequency in the laboratory. Initially a Westerwolds and a hybrid cultivar showed greater yield reductions than an Italian ryegrass cultivar, although they did not usually suffer a higher proportion of damaged tillers. The differing effect on yield appeared to be due mainly to greater impact of first or infrequent attacks on cultivars producing fewer tillers. After two to six attacks in approximately 7 months the Westerwolds and hybrid cultivars appeared to become tolerant to attack and were subsequently the least affected, although continuing to suffer tiller damage at a rate at least as high as the Italian ryegrass. All cultivars recovered fully when attack ceased, and their exclusion from attack did not improve their persistence.     

Chemical control of onion fly, Delia antiqua

In nine trials done in 1972-4 seed treatments reduced attacks of onion fly larvae very effectively and most of the organophosphorus formulations gave protection up to harvest, 12–17 wk after sowing. Pirimiphos-ethyl and isofen-phos each at 10 or 20 g a.i./kg seed controlled onion fly larvae well and they were not seriously phytotoxic in any of the trials. Chlorpyrifos, trichloronate, ethion, iodofenphos, chlorfenvinphos wettable powder or triazophos all at iog a.i./kg seed were also effective, but they were tested in fewer trials. Diazinon at 10 or 20 g a.i./kg seed, carbophenothion and chlorfenvinphos liquid seed dressing at 10 g a.i./kg seed controlled onion fly well, but in some trials they were phytotoxic; methiocarb, mecarphon and oxamyl were much less effective. At 1–12 kg a.i./ha chlorfenvinphos granules applied over the rows shortly before the attack was expected was the best granular formulation, but it was not as effective as the better seed treatments.     

Revealing hereditary variation of winter hardiness in cereals

A set of cereal crops and differentiating cultivars was shown to be of utility for identifying the major abiotic factors that limit the survival of winter crops in the cold season of a particular year. With this approach, the season was identified (1997-1998, Belgorod) when the survival of cereals depended on the tolerance to anaerobiosis rather than on the frost resistance. Differentiation of common wheat cultivars with respect to this property was attributed to a locus designated Win1 (Winter hardiness 1) and localized 3.2-5.8% recombination away from the B1 (awnlessness) gene. Winter barley (cultivar Odesskii 165) displayed the highest tolerance to anaerobiosis in the cold season; low and intermediate tolerance was established for winter durum wheat (cultivar Alyi Parus) and winter common wheat, respectively. Frost resistance and winter hardiness type 1 proved to be determined by different genetic systems, which showed no statistical association. Correlation analysis revealed significant positive associations of frost resistance in the field (1996-1997, Belgorod) with productivity, sedimentation index, plant height, and vegetation period in wheat. Statistical analysis associated frost resistance with gliadin-coding alleles of homeologous chromosomes 1 and 6 of the A, B, and D wheat genomes.     

Chemical control of wheat bulb fly (Delia coarctata) attacking winter wheat in Eastern England, 1969–1981

Dry powder, liquid and microencapsulated formulations of organophosphate and synthetic pyrethroid insecticidal seed treatments were tested as possible alternatives to the standard organochlorine seed treatments for autumn-sown wheat in mineral and organic soils heavily infested with wheat bulb fly eggs and (subsequently) larvae. Retention of insecticides on the seed coat varied from 40% to 120% of the target dose; it was usually good when microencapsulated formulations were used. Chlorfenvinphos, fonofos, isofenphos and triazophos, each applied at 2-0 g a.i./kg seed, were phytotoxic, the symptoms varying from a slight delaying effect upon germination to an adverse effect upon grain yield. Chlorfenvinphos at 0–2 to 2-0 g a.i./kg seed was consistently effective against wheat bulb fly larvae in both mineral and organic soils. Athidathion 0–8 g a.i./kg, carbophenothion 1–2 g a.i./kg, ethion 1–7 g a.i./kg and fonofos (microencapsulated formulations) at 1-0 or 2-0 g a.i./kg were also effective in mineral and organic soils. Of the synthetic pyrethroids tested as seed treatments, permethrin gave excellent results in mineral soils at 1-0 g a.i./kg or in synergised formulations at 0–12 or 0–24 g a.i./kg but was disappointing in organic soils. In a single comparison of seed treatments applied to wheat sown early (14 October) and late (20 November), chlorfenvinphos was effective at both sowing dates whereas athidathion, ethion and pirimiphos-ethyl gave better results in late-sown wheat. A single trial compared deep with shallow sowing of treated seed. Most insecticides performed better on shallow-sown wheat, but chlorfenvinphos was equally effective against the pest at both sowing depths. Most insecticides restricted the numbers of larvae entering host plants but had little or no subsequent effect upon larval survival within attacked shoots. Fonofos and isofenphos, and to a lesser extent chlorfenvinphos, seed treatments additionally killed many larvae within plant shoots.     

Chemical control and insecticide resistance status of sand fly vectors worldwide

BackgroundPhlebotomine sand flies are prominent vectors of Leishmania parasites that cause leishmaniasis, which comes second to malaria in terms of parasitic causative fatalities globally. In the absence of human vaccines, sand fly chemical-based vector control is a key component of leishmaniasis control efforts.Methods and findingsWe performed a literature review on the current interventions, primarily, insecticide-based used for sand fly control, as well as the global insecticide resistance (IR) status of the main sand fly vector species. Indoor insecticidal interventions, such as residual spraying and treated bed nets are the most widely deployed, while several alternative control strategies are also used in certain settings and/or are under evaluation. IR has been sporadically detected in sand flies in India and other regions, using non-standardized diagnostic bioassays. Molecular studies are limited to monitoring of known pyrethroid resistance mutations (kdr), which are present at high frequencies in certain regions.ConclusionsAs the leishmaniasis burden remains a major problem at a global scale, evidence-based rational use of insecticidal interventions is required to meet public health demands. Standardized bioassays and molecular markers are a prerequisite for this task, albeit are lagging behind. Experiences from other disease vectors underscore the need for the implementation of appropriate IR management (IRM) programs, in the framework of integrated vector management (IVM). The implementation of alternative strategies seems context- and case-specific, with key eco-epidemiological parameters yet to be investigated. New biotechnology-based control approaches might also come into play in the near future to further reinforce sand fly/leishmaniasis control efforts.     

Field-scale effects of farming practices on linyphiid spider populations in grass and cereals

Linyphiid spiders were sampled in three grass and four cereal fields, between October 1989–October 1990, and from one grass and one cereal field, from June–August 1991. Population growth and decline were characteristic of field type and pattern of management. Agricultural operations caused large population depletions: insecticide applications, cutting grass for silage and autumn cultivations reduced spider populations by 56% to 96%; heavy grazing caused virtual extinction. Aerial dispersal activity, monitored by water traps, showed high dispersal frequency with highest intensity in June, July and August. The results are discussed with reference to the large-scale spatial structure of linyphiid spider populations and the use of spatially dynamic models to predict metapopulation size as a function of patterns of crop management, land-use and landscape structure.     

Growth and development of root systems of winter cereals grown after different tillage methods including direct drilling

Summary A method is described for rapidly estimating the depth of penetration and density of roots of cereal crops under field conditions. Counts of living roots, traversing horizontal faces of soil cores, were made for winter wheat growing on direct-drilled and ploughed land.The rate of penetration of roots of winter wheat in a clay and a sandy loam soil averaged 5 mm per day throughout winters without extremes of cold or wet. Death of roots near the soil surface occurred wilst others continued downward penetration. The rate of root elongation was slower during prolonged periods when the soil was wet and faster,i.e. to greater depths, during dry conditions.Damage sustained to roots during adverse winter conditions ofter varied between direct drilling and ploughing. More roots at depth were consistently recorded on direct-drilled than on ploughed land when measured in spring after a soil water deficit had developed during the preceding month. After prolonged wet soil conditions during the winter on a soil with a large clay fraction and low hydraulic conductivity, root growth and penetration in spring, before the development of a soil water deficit, was more restricted on direct-drilled than on ploughed land.     

Phylogenetic relations between frit fly groups from the genus Meromyza based on genetic and morphological analysis

Phylogenetic relations between groups of frit fly species from the genus Meromyza were studied on the mtDNA COI locus and on the morphology of the male reproductive apparatus. Branching of the phylogenetic tree constructed by the Neighbor-Joining method unites sequences of samples from species of the genus Meromyza in five clusters with high support. It was demonstrated that joining of species in a certain cluster corresponds to uniformity of morphological traits of male parameres.     

Determination of unfrozen water in winter cereals at subfreezing temperatures

The freezing of water in acclimated and nonacclimated cereals was studied using pulsed nuclear magnetic resonance spectroscopy. The quantity of unfreezable water per unit dry matter was not strongly dependent on the degree of cold acclimation. In contrast, the fraction of water frozen which was tolerated by nonacclimated winter cereals and by an acclimated spring wheat (Triticum aestivum L.) was less than in acclimated hardy cereals. The freezing curves had the following form:L_T = L₀ΔTm/T + KL_T and L₀ are liquid water per unit dry matter at T and 0 C, respectively. ΔTm is the melting point depression and K is the liquid water which does not freeze.     

不同播期冬小麦株型构建及其生育特征

针对黄淮平原中部冬小麦区秋季旱涝频发导致小麦播种推迟的现状,设计冬小麦10月15日(适期播种)、10月30日(中晚期播种)、11月15日(晚期播种)、11月30日(超晚期播种)、2月15日(早春播种)和3月1日(春播)6个播期,研究不同播期冬小麦株型构建及生长发育特征.结果表明： 随着冬小麦播期的推迟,其生长发育进程加快,早春播种和春播与适期播种相比生育期缩短115~130 d;10月30日(中晚期播种)之后的5个播期与适期播种相比株高降低,成穗数和有效小穗数减少;迟播小麦的叶位下移,冠层空间降低,叶面积减少;收获指数随播种期推迟由0.46(适期播种)提高到0.53(春播);冬小麦产量随播种期推迟显著下降,减产幅度最高达43.6%;冬小麦春季播种未经过冬季和早春阶段的自然低温处理,无春化过程依然可形成产量.     

Biological control of snow mould (Microdochium nivale) in winter cereals by Pseudomonas brassicacearum, MA250

Seed lots of winter wheat and rye, naturally infested with Microdochium nivale and Fusarium spp., were treated with an isolate of Pseudomonas, which was recovered from roots of Brassica napus. Seeds were treated with bacterial fermentate and dried before sowing or they were directly sprayed in the furrow-opener at the moment of sowing. Besides field experiments, parallel climate chamber bioassays were performed to assess the effect of bacterial treatment on snow mould caused by seed-borne M. nivale and Fusarium spp. The biocontrol effect was assessed by plant density counts and by measuring yield. Significant biocontrol activity, measured by plant density counts, was detected both in field and climate chamber experiments sown with wheat. Biocontrol effect after spray application at sowing was less pronounced, although a slight increase in plant density was observed. The cell concentration required to obtain adequate biocontrol effect was 10⁹ CFU per ml for the dose used. The bacterial isolate was identified by 16S rDNA sequencing and biochemical tests as a Pseudomonas brassicacearum strain.     

粉煤灰基质上草坪草苗期生长状况及其评价

在未施肥的条件下,采用盆栽试验对粉煤灰、粉煤灰 泥炭土、粉煤灰 黄砂土、泥炭土、黄砂土5种基质上8种草坪草的苗期生长状况进行了研究。结果表明,白三叶、红三叶、黑麦草、高羊茅和马蹄金种子在粉煤灰基质上出苗快,其出苗率、苗高、分蘖数均高于粉煤灰 泥炭土和粉煤灰 黄砂土基质;但在后期出现叶片纤细、叶绿色浅淡。剪股颖在粉煤灰基质上出苗率低,结缕草和紫羊茅在粉煤灰基质上不出苗。     

Observations on the oviposition behaviour of frit fly (Oscinella frit L. dipt. chloropidae)

Two separate groups of stimuli (1) originating from the plant, (2) proprioceptive, have been found to mediate egg laying. An artificial shoot has been devised to investigate oviposition behaviour.

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Zusammenfassung Die Eiablage wird durch eine Anzahl von Reizen ausgelöst, die nacheinander wirken, jedoch im einzelnen nicht genauer identifiziert wurden. Sie lassen sich jedoch in zwei Gruppen trennen: (1) Reize, die von der Wirtspflanze selbst ausgehen und (2) solche, die wahrscheinlich propriorezeptiv wirken und auf der Notwendigkeit einer geeigneten Haltung der Beine und des Legeapparates während des Eiablageaktes beruhen.Die propriorezeptiven Reize scheinen die Fliegen häufig von den Keimpflanzen weg und zur Ablage ihrer Eier auf dem Boden zu führen, was darauf hindeutet, daß die Eier im Freien in ähnlicher Weise in den Erdboden abgelegt werden.Ein Extrakt aus in Wasser zerriebenen Haferpflanzen scheint in Verbindung mit einer geeigneten Oberfläche (z.B. Erdboden oder Sand) Eiablageverhalten auszulösen. Verschiedene Resultate wurden mit glatt oder rauh strukturierten Oberflächen und in Abhängigkeit von Gegenwart oder Abwesenheit des Extraktes erhalten. Die Reaktion der Fliegen scheint mit dem physiologischen Zustand des Gewebes zu variieren, das den Fliegen geboten wird, und das Eiablageverhalten ist schwach, wenn den Fliegen alte oder absterbende Pflanzenteile geboten werden. Die Wahrscheinlichkeit, daß Reize, welche Nahrungsaufnahme, und solche, die Eiablage hervorrufen, ursprünglich nicht die gleichen sind, ist nur gering.Eine künstliche Keimpflanze, die von den Fliegen zur Eiablage ebenso angenommen wurde wie eine junge, gesunde, lebende, wurde dadurch hergestellt, daß ein dreieckiges Stück Fließpapier mit Haferextrakt befeuchtet und in das Innere einer 2,5×2,5 cm Glastube gesteckt wurde.

     

Efficiency of cold hardiness induction by desiccation stress in four winter cereals

A number of defined desiccation treatments without low temperature exposure were able to induce freezing tolerance in 20 cultivars of winter cereals. A maximal degree of freezing tolerance was induced in epicotyls at 24°C in 24 hours at 40% relative humidity in rye and wheat, 7 days at 54% RH in barley, and 4 days at 70% RH in oats. Freezing tolerance was not correlated to water content of the plants after desiccation treatment but was related to the genetic capacity of the cultivars to frost harden. Levels of freezing tolerance induced by desiccation were similar to those induced by cold acclimation in rye and wheat, but considerably less in barley and oats. This is associated with a more rapid desiccation injury in barley and oats, precluding the completion of the hardening process.