Time-controlled cholinesterase reactions as a means of measuring water-soluble residues of organophosphorus insecticide spray deposits on plant surfaces

Ellman's method of cholinesterase assay which is often used for residue analysis of organophosphorus insecticides has been modified by adding the protein denaturant, sodium dodecyl sulphate, to control the duration of the reaction. In doing so, the reaction time can be standardised to facilitate the measurement in a field laboratory of residues of water-soluble organophosphates, particularly on plant surfaces that have been subjected to sprays. Thirty samples can be analysed in 1 h by timing each step of the procedure for a series of 30 reaction tubes at 1-min intervals from the incubation of the enzyme with the insecticide to the final addition of the sodium dodecyl sulphate. Results from a series of aerial spray trials are presented and discussed briefly as an example of a field application of the method.     

高温逆境条件下碧护对杂交水稻产量的影响

水稻是我国总产量最高的粮食作物,栽培范围遍及全国各地。随着水稻轻型栽培技术推广和近年来极端天气频繁出现,特别是高温、干旱等情况越来越重,水稻开花结实受到干扰,使花粉不育,导致空壳率增高,严重影响水稻产量。     

Effect of atrazine on growth, production of aflatoxin, and fatty acid and sterol biosynthesis by Aspergillus spp.

The effects of atrazine were studied on growth, production of aflatoxin, and fatty acid and sterol biosynthesis by four isolates of Aspergillus in vitro. There was little effect of atrazine on Aspergillus spp. at concentrations up to 20 μg ml^?1 but at 40 μg ml^?1 or above, growth, production of aflatoxin, and fatty acid and sterol biosynthesis were remarkably reduced. Palmitic, stearic and linoleic acid synthesis were inhibited in three of the isolates tested at 60 μg ml^?1. At 100 μg ml^?1, except ergosterol, the cholesterol and 5, 7-ergostadienol synthesis was totally inhibited in all isolates. Effet de l'atrazine sur la croissance, la production d'aflatoxine, et la biosynthèse d'acides gras et de stérols par Aspergillus spp. Chez quatre isolats d'Aspergillus, les effets de l'atrazine sur la croissance, la production d'aflatoxine, et la biosynthèse d'acides gras et de stérols ont étéétudiés in vitro. Jusqu'à des concentrations de 20 μg ml^?1, l'atrazine n'a eu que peu d'effets, mais à 40 μg ml^?1 et au-dessus, la croissance, la production d'aflatoxine, et la biosynthèse d'acides gras et de stérols ont été nettement réduites. Les synthèses d'acides palmitique, stéarique et linoléique ont été inhibées chez trois des isolats, à 60 μg ml^?1. A 100 μg ml^?1, mis à part l'ergostérol, les synthèses de cholestérol et de 5, 7-ergostanediol ont été totalement inhibées chez tous les isolats. Die Wirkung von Atrazin aufdas Wachslum, die Bildung von Aflatoxin und die Fettsäuren- und Sterol-Biosynthese von Aspergillus spp. Bei vier Isolaten von Aspergillus wurde in vitro die Wirkung auf das Wachstum sowie auf die Bildung von Aflatoxin, Fettsäuren und Sterolen untersucht. Bei Atrazin-Konzentrationen bis zu 20 μg ml^?1 war keine Wirkung zu beobachten, aber ab 40 μg ml^?1 wurden das Wachstum und die Bildung von Aflatoxin, Fettsäuren und Sterolen deutlich herabgesetzt. Bei 60 μg ml^?1 war bei drei Isolaten die Bildung von Palmitin-, Stearin- und Linolensäure gehemmt. Bei 100 μg ml^?1 war bei alien Isolaten die Bildung von Cholesterol und 5, 7-Ergostadienol, aber nicht Ergosterol, unterbunden.     

The efficacy of a petroleum spray oil against Aphis gossypii Glover on cotton. Part 1: mortality rates and sources of variation

Petroleum spray oils (PSOs) kill insect pests on contact, and the composition of modern PSOs is substantially different from the ones introduced earlier. The effects of direct application of a new nC24 PSO on the cotton aphid, Aphis gossypii Glover, were therefore determined. This covered not only aphid mortality rates but also the way in which the oils affected aphid behaviour at the time of contact with the oil. Direct application of the nC24 oil proved to be highly effective in controlling A. gossypii at a range of concentrations between 1 and 10% v/v. The oil killed cotton aphids quickly, with most of the mortality occurring within the first 10 min of spraying. The fast killing action of the oils prevented any behavioural responses by the aphids. Aphids killed by the oils became flaccid and their legs and antennae extended horizontally relative to the body axis. With time, their cuticle became very shiny and began to darken. The quick death of the aphids suggested a contact mode of action of the oils, an interpretation supported by the lack of any negative effect on aphids not initially reached by the oils. However, those aphids not hit by the oils, but that subsequently encountered oil-treated areas when they moved elsewhere, also died, indicating that the oil deposits are also toxic to the aphids. The mode of action of the oil thus seems to be versatile, and the means by which it kills the aphids may be more complex than anoxia, which is the widely claimed mechanism attributed to PSOs. This oil now needs to be tested for any possible indirect effects on the cotton aphid (e.g. through its host-plant acceptance behaviour). The implications of the present findings for cotton aphid control and assessment of PSO efficacy in the field are discussed.     

Studies on the sterile male technique as a means of control of Adoxophyes orana (Lepidoptera,Tortricidae). 5. Release trials

In release trials with sterile males ofAdoxophyes orana in an apple orchard of 1.4 ha in 1971 and in an other orchard of 1.9 ha in 1973 and 1974 a marked decrease in the population ofA. orana was observed. Release of sterile males seemed to cause the effect. Immigration of moths, usually not more than a few hundreds, did not disturb the programme but would obviously prevent eradication and control at low level. Other tortricids increased in the absence of chemical control but less competition fromA. orana might also offer some explanation. The other tortricids were responsible for up to 9% damage among apples. Consequently the sterile male method specifically against one pest does not result in an important reduction in the number of sprays and a specific control method is not always the solution to pest problems in integrated control.Samenvatting Twee loslaatproeven met steriele mannetjes ter bestrijding van de vruchtbladrollerAdoxophyes orana worden beschreven.In de eerste, uitgevoerd in 1971 bij Overberg, werden 41000, met 25 krad gamma-stralen gesteriliseerde mannetjes bij de eerste vlucht, en 56000 tijdens de tweede vlucht losgelaten. In geen van de proeven werden de mannetjes van de wijfjes gescheiden. De sexe verhouding was circa 11. Alle losgelaten motten waren gemerkt met Calco Red Oil D. Terugvangsten met vanglampen gaven een verhouding tussen losgelaten en wilde motten van 41 in de eerste vlucht en 131 in de tweede vlucht (Tabel 3). Tellingen van de aantallen larven, door het afzoeken van hele bomen, wezen op teruggang van het aantal rupsen (Tabel 4). De vangst aan wilde mannetjes in de vanglamp wijst op een duidelijke immigratie uit de omgeving (Tabel 3). Het aantal andere bladrollersoorten bleek sterk toe te nemen (Tabel 4).In de tweede proef, uitgevoerd in 1973 en 1974 bij Lienden, werden tijdens de eerste en tweede vlucht van 1973 resp. 17000 en 37000 mannetjes losgelaten en in 1974 resp. 55000 en 26000. De bestralingsdosis bedroeg 25 krad. De wijfjes werden in gelijke aantallen mee losgelaten. De motten waren gemerkt met Rotor kleurstoffen en werden teruggevangen in feromoonvallen. De terugvangverhouding bedroeg in 1973 tijdens de eerste vlucht 91 (Tabel 3). In 1974 was deze resp. 91 en 211. De larvetellingen (Tabel 4) wezen weer op sterke teruggang vanA. orana. Ook hier bleken andere soorten sterk in aantal toe te nemen (Tabel 5) zodat toch nog een vrij belangrijke bladrollerschade in de oogst ontstond.Hoewel de populatiedaling in beide proeven zeer duidelijk was, kan toch nog niet met zekerheid tot succes van de methode worden geconcludeerd omdat in de laatste jaren de betekenis vanA. orana in geïntegreerd bestreden percelen afnam. Een belangrijke moeilijkheid blijkt ook de statistische bewerking van de tellingen te zijn, daarA. orana zeer sterk pleksgewijs voorkomt. Het verdelingstype kon niet altijd worden vastgesteld maar leek soms op dat van een negatieve binomiaal met k-waarden keliner dan 1 (Tabel 6).Ook in deze proef werden aanwijzingen voor immigratie gevonden (Tabel 8). Deze is niet zo sterk dat het loslaatprogramma werd verstoord maar zou wel een uitvoerige campagne in de weg staan.Door het toenemend optreden van andere bladrollersoorten wordt het doel van de specifieke bestrijding vanA. orana verijdeld, daar toch nog chemische bestrijding noodzakelijk blijft. De specifieke bestrijdingsmethode hoeft dus niet altijd een oplossing van een plaagprobleem in de geïntegreerde bestrijding te geven.     

Studies on the sterile-male technique as a means of control of Adoxophyes orana (Lepidopt., Tortricidae). 1. Problems of mass rearing (crowding effects)

Almost all larvae ofAdoxophyes orana F.R. mature if they are individually confined in vials. In gregarious culture, 2 or 4 larvae per vial, growth is retarded and many larvae die because of frequent fighting. This aggression results from the biggest larvae holding other larvae off the food. Retarded development was not due to optical or olfactory causes, but to food deprivation. In mass rearing the setback can be partly overcome by adding plastic strips that increase the cover for the larvae in rearing boxes.Samenvatting Massakweken vanAdoxophyes orana zijn noodzakelijk voor de ontwikkeling van een steriele-mannetjesprogramma ter bestrijding van deze plaag. In kweken in buisjes werd een agressief gedrag van de opgroeiende rupsen waargenomen wanneer zich meer dan 1 rups per buis bevond. Hierdoor werd de groeisnelheid vertraagd en trad bij 4 larven per buis veel sterfte op (Fig. 1 en 2, Tabel 1). Deze groeieffecten hadden geen optische of olfactorische oorzaak. Wanneer de larven meer ruimte kregen nam wel de mortaliteit af (Tabel 3) maar niet de groeivertraging (Tabel 4). Verstoring van de larven beïnvloedde hun groei nadelig (Tabel 5 en 6). De groeivertraging is echter voor het grootste deel te wijten aan hongeren (Tabel 7) doordat in de kweek de grotere larve de toegang tot het voedsel ontzegt aan de kleinere.In massakweken kan de hieruit voortvloeiende groeivertraging en mortaliteit worden verminderd door plastic strips in de kweekbakken te plaatsen waardoor het aantal schuilplaatsen voor de larven toeneemt.     

Note: Effects of plant oils and adhesive stickers on the mycelia growth and conidiation ofVerticillium lecanii, a potential entomopathogen

Oils enhance the efficacy of entomopathogens used as augmentative biological control agents. The effect of cheap and commonly available various plant oils,viz., sunflower oil, neem oil, pongamia oil, castor oil, gingili oil, coconut oil, groundnut oil, and the adhesive stickers laboline and Triton-X100, onVerticillium lecanii, an entomopathogen recommended for the control of major sucking pests of horticultural importance, was studied. The first four oils screened, significantly enhanced mycelia growth and conidiation. Gingili oil, coconut oil, groundnut oil and Triton-X100 were found to be poor carriers ofV. lecanii in relation to mycelia growth and conidiation. http://www.phytoparasitica.org posting July 14, 2005.     

Studies on the diagnosis of hop stunt viroid in fruit trees: Identification of new hosts and application of a nucleic acid extraction procedure based on non-organic solvents

A non-radioactive digoxigenin-labelled RNA probe specific for hop stunt viroid (HSVd) diagnosis has been developed. The high sensitivity and specificity of this RNA probe in dot blot hybridizations to nucleic acids from field samples, allowed the confirmation of the presence of HSVd in apricot (Prunus armeniaca L.) and its detection in two fruit tree species not previously described as hosts of this pathogen, almond (Prunus dulcis Miller) and pomegranate (Punica granatum L.). This result supports and extends the notion of the world wide distribution of HSVd, infecting cultivated fruit trees. HSVd was also found to accumulate to much higher levels in mature apricot fruits than in leaves. Additionally, a sample processing procedure which does not involve the use of organic solvents was demonstrated to render faithful results when used for viroid detection. The combined reliability and facility of use of both this extraction procedure and the non-radioactive probe will benefit agronomic investigations addressing the detection and eradication of HSVd. Other applications of the work described here, as the study of possible causal relations between specific disorders and HSVd infection, are also discussed.     

Physiological actions of dinoterb,a phenol derivative: 1. Physiological effects on the whole plant and on tissue fragments of pea

The herbicide dinoterb is a tert.-butyl-2-dinitro-4,6-phenol. Its effects on the metabolism (water, dry matter, nitrogen, chlorophyll, and flavonol contents) were studied on pea plants (Pisum sativum L.). Concurrently, photosynthesis and respiration intensities of treated plants or tissues were measured (O₂ emission or uptake measured on leaf fragments in the reaction vessel of a Clark-type electrode system). Dinoterb, which is an inhibitor of photosynthesis of isolated, physiologically active chloroplasts, also appeared to rapidly inhibit photosynthesis in the whole plant. This property was used for an indirect method of analysis of dinoterb movement in the leaf and in the plant. Dinoterb appears to have a complex mode of action: low concentrations of the herbicide, rapidly appearing in the whole treated leaf, inhibited photosynthesis, uncoupled oxidative phosphorylations, and began to inhibit respiratory oxygen consumption. High concentrations of dinoterb were responsible for important necrosis some days after treatment and we could show, by analysis of the flavonolic accumulation, that cells of the upper epidermis seemed to be first affected.     

Performance of three endophytic actinomycetes in relation to plant growth promotion and biological control of <Emphasis Type="Italic">Pythium aphanidermatum</Emphasis>, a pathogen of cucumber under commercial field production conditions in the United Arab Emirates

In the current study, the performance of three endophytic actinomycetes identified as Actinoplanes campanulatus, Micromonospora chalcea and Streptomyces spiralis previously shown to reduce seedling damping-off, and root and crown rots of mature cucumber (Cucumis sativus) caused by Pythium aphanidermatum in pots under greenhouse conditions were further evaluated to determine their potential as biological control agents and as plant growth promoters in the field under the conditions of commercial production of cucumbers in the United Arab Emirates (UAE). When applied individually or in combination to cucumber seedlings, the three isolates significantly promoted plant growth and yield and reduced seedling damping-off and root and crown rots of mature cucumber plants. Individually the performance level of S. spiralis was relatively the best followed by A. campanulatus and then by M. chalcea. The three isolates (which were not inhibitory to each other) performed better, both as biological control agents as well as plant growth promoters, when applied together than when they were inoculated individually. The ability of these three isolates to colonize the internal tissues of roots, stems and leaves under field conditions, and to persist up to 8 weeks after seedling inoculation, showed that they can easily adapt to an endophytic habit systemically within healthy cucumber plants. As the three endophytic actinomycete isolates also colonized the rhizosphere and showed outstanding rhizosphere competency it is clear that they are facultative and not obligate endophytes. The success with the three inoculants indicated that they could well be used in place of the fungicide metalaxyl which is currently recommended for the management of Pythium diseases in the UAE. This is the first successful field use of endophytic actinomycetes as promising plant growth promoters and biological control agents against Pythium diseases of cucumber.     

Studies on the sterile-male technique as a means of control of Adoxophyes orana F.R. (Lepidoptera,Tortricidae). 2. Dose-response curves after irradiation of the moths with X-rays or fast neutrons

Every degree of sterility can be induced in young months (up to 24 h old) ofAdoxophyes orana F.R. with ionizing radiation. Measurements under experimental conditions did not reveal any effect of the dosages used on life-span, mating frequency and fecundity. The same doses of radiation induced a higher degree of sterility in female moths than in male ones.The relative biological effectiveness of fast neutrons to X-rays is 2.5–5.0, as indicated by the parameter induction of dominant lethal factors in 90% of the reproductive cells.Samenvatting Uit bestralingsexprimenten met motten (hooguit 24 uur oud) vanAdoxophyes orana F.R. is gebleken dat zowel met X-stralen als met snelle neutronen iedere gewenste graad van steriliteit geïnduceerd kan worden, zonder een, onder de proefomstandigheden te meten effect op levensduur, paringsfrequentie en aantal gelegde eieren (Fig. 1, 2, 3 en 4). Vrouwelijke motten blijken gevoeliger voor inductie van steriliteit door beide soorten ioniserende straling dan mannelijke motten (Fig. 1 en 2).Proeven ter bepaling van het effect van de doseringssnelheid en van gefractioneerde bestraling (Tabel 1 en 2) geven aanwijzingen dat enzymatische herstelprocessen geen grote rol spelen. Wel zijn aanwijzingen gevonden dat na verloop van enkele dagen, misschien ten gevolge van afsterven van beschadigd sperma, het percentage steriliteit afneemt (Tabel 3). De RBE van snelle neutronen ten opzichte van X-stralen met dominant lethale factoren in 90% van de vootplantingscellen als parameter, blijkt 2,5 voor vrouwelijke motten en 5 voor mannelijke motten te bedagen.De verzamelde gegevens vormen een basis voor verder onderzoek naar praktische mogelijkheden van een steriele-mannetjestechniek en semisteriliteit en voor meer fundamenteel onderzoek naar bijv. de wijze van overerving van semisteriliteit en naar stralingsbiologische aspecten in het algemeen.     

Cry1Ac毒蛋白对亚洲玉米螟生长发育和种群增长的影响

以含不同浓度的Cry1Ac毒蛋白的人工饲料(不加毒蛋白为对照)饲喂亚洲玉米螟幼虫,采用实验种群生命表的方法,测定了Cry1Ac毒蛋白对亚洲玉米螟的控害作用。结果显示,含2 000.0ng/g Cry1Ac毒蛋白的人工饲料处理该虫第5天的幼虫存活率为0;200.0、20.0 ng/g CrylAc毒蛋白处理第10、15天的幼虫存活率、化蛹率、成蛾率、净增长率和种群增长指数均显著低于对照,且高浓度处理显著低于低浓度处理;200.0 ng/g CrylAc毒蛋白处理的世代平均周期和种群加倍时间显著长于其它处理;而200.0 ng/g CrylAc毒蛋白处理的周限增长率显著小于2.0、0.2 ng/g处理。表明微量的Cry1Ac毒蛋白对亚洲玉米螟的种群增长有显著影响,且随着浓度的增加控制作用增强。     

Overcompensation of seed production caused by clipping of Bidens pilosa var. radiata (Compositae): Implications for weed control on Iriomote‐Jima Island,Japan

The invasion of natural ecosystems by exotic species is a major threat to biodiversity on a local, regional, and global scale. Endemic island flora are particularly vulnerable to invasive species. Bidens pilosa var. radiata is a common invasive weed of roadsides, which are subject to clipping, on Japanese subtropical islands. To assess compensation by the weed to damage by clipping, a pot experiment was conducted under common garden conditions. The above‐ground parts were clipped with pruning shears at various frequencies, ranging from no clipping (the control) to clipping at 4–16 week intervals for 32 weeks in summer. The clipped individuals regenerated new branches from the axillary buds and flowered for ≤12 weeks after the clipping. The regeneration after the clipping gave rise to secondary reproduction, whereas minimal regeneration occurred in the unclipped individuals after the maturation of the fruit. Consequently, the total flower head mass, represented by the dry weight of the inflorescences throughout the experiment, was higher on the individuals that were clipped at 12 and 16 week intervals than on the unclipped individuals, suggesting overcompensation in fecundity. At the higher frequencies of above‐ground clipping, the flower head mass was suppressed at 8 week clipping intervals, while both the flower head mass and the productive biomass were suppressed at 4 week clipping intervals. This indicates that clipping at intervals of ≤8 weeks is required to prevent the reproduction of this weed.     

Bioassays on the role of tomato,potato and sweet pepper as sources of <Emphasis Type="Italic">Tomato chlorosis virus</Emphasis> transmitted by <Emphasis Type="Italic">Bemisia tabaci</Emphasis> MEAM1

Shot hole disease of stone fruits caused by Thyrostroma carpophilum has become a major threat to stone fruit industry of Jammu and Kashmir, India because of the failure in its management with fungicides. To understand the diversity in shot hole pathogen, a combination of conventional (morphological, cultural and pathological) and molecular (ISSR and ITS markers) approaches were employed to discern variability in 25 isolates of T. carpophilum isolated from peach, plum, apricot, almond and cherry leaves collected from Srinagar, Ganderbal, and Baramulla districts of Jammu and Kashmir, India. The studies revealed a high level of variability among the pathogen. Based on the morpho-cultural and pathological studies, the isolates were grouped into different categories based on colony growth, texture, margin and colour besides change in media colour, incubation period, leaf area infected, etc. Using ISSR markers, a high level of polymorphism in different isolates of T. carpophilum was observed which indicated that these markers are suitable for studying the genetic diversity in this pathogen. Based on dendrogram, the isolates were grouped irrespective of their geographical origin or host species. Phylogenetic analysis of the 25 sequences based on ITS region showed maximum similarity with T. carpophilum (Syn. Wilsonomyces carpophilus) sequences retrieved from NCBI and grouped them in a single clade which proved it as a powerful tool for authentic identification. The pathogen was highly variable based on morpho-cultural, pathological and molecular (ISSR) characterisation.     

Discovery of a sooty mould scavenging beetle, <Emphasis Type="Italic">Leiochrinus nilgirianus</Emphasis> Kaszab (Coleoptera: Tenebrionidae) on coconut palms infested by the invasive rugose spiralling whitefly, <Emphasis Type="Italic">Aleurodicus rugioperculatus</Emphasis> Martin (Hemiptera: Aleyrodidae)

Scavenging action of Leiochrinus nilgirianus Kaszab (Coleoptera: Tenebrionidae) on sooty mould deposition on coconut palms due to heavy honeydew production by the invasive rugose spiralling whitefly, Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae), is reported for the first time from Kerala, India. Adult beetles, averaging 2.07?±?0.9 / leaflet, with a maximum of five beetles per leaflet, and immature stages were generally confined to the abaxial of the palm leaves during daytime, but were found feeding on sooty mould during morning hours in damp conditions. The specially aided adaptive leg features of L. nilgirianus with bristle-like hairs on the undersurface of tarsomeres probably aid in proper adhesion on sooty mould laden plant surface and well developed tarsal claws that perhaps assist swift movement on fungus-laden leaflets. On an average one adult beetle could clear 1–2 mm² sooty mould laden area in a period of one minute. In situ habitat conservation of L. nilgirianus would help to reduce the sooty mould at no cost in the most natural and eco-friendly manner avoiding chemical management options and other expensive methods.