Methacrifos as a grain protectant: A comparison of the vapour effects of some organophosphorus insecticides used in grain protection

A simple Sradiochemical method was devised for the estimation at ambient temperatures of vapour uptake and toxicity of relatively non-volatile organophosphorus insecticides to the red flour beetle Tribolium castaneum. Over a three-day period the insecticides pirimiphos-methyl and chlorpyrifos-methyl exhibited no vapour activity and only small amounts of vapour were accumulated by test insects. Methacrifos appeared to be much more active as a vapour and much of its toxic action in an ideal situation could be attributed to this phenomenon.     

Abscisic acid as a protectant of Avena fatua L. against diclofop-methyl activity

The imposition of water stress before or al the time of spraying diclofop-methyl reduced efficacy against wild oat (Avena fatua L.). Similar reductions in herbicide performance were obtained by application of 20 μg of the methyl ester of abscisic acid (ABA) to plants with three to four leaves before spraying with I kg ha^?1 diclofop-methyl. Application of 40–100 μg ABA per plant effectively protected plants against damage from diclofop-methyl applied at 1 5–2 0 kg ha ^?1. The application of 20 μg ABA induced rapid stomatal closure and a reduction in leaf extension rate, which were sustained for 7–8 days after treatment. These changes were associated with an overall reduction in shoot growth. ABA-treated plants that were additionally sprayed with diclofop-methyl sustained ABA symptoms, but no additional weight loss or leaf chlorosis. The mechanism of the protective action of ABA on diclofop-methyl has not been determined.     

Effectiveness of allyl acetate as a fumigant against five stored grain beetle pests

Five esters, butyl acetate, allyl acetate, ethyl acetoacetate, isopropyl acetate and propyl acetate, were screened as fumigants in the laboratory for 24 h at 27 (+/-2) degrees C against the adults of Rhyzopertha dominica (F), Sitophilus oryzae (L) and Tribolium castaneum (Herbst). Of the compounds tested, allyl acetate was the most toxic, with LD(99) values of 7.56, 12.81 and 11.42 mg litre(-1) against R dominica, S oryzae and T castaneum, respectively. Tests with allyl acetate against mixed-age cultures of Cryptolestes ferrugineus (Stephens), Oryzaephilus surinamensis (L), R dominica, S oryzae and T castaneum revealed that doses of 50-150 mg litre(-1) with 24-120-h exposures were necessary to achieve 100% mortality of all life stages. Cryptolestes ferrugineus was the most tolerant insect tested, whilst R dominica was highly susceptible. The insect toxicity data indicates that allyl acetate has potential as a fumigant of stored food grains.     

Toxicity and protectant potential of camphor,a major component of essential oil of Ocimum kilimandscharicum,against four stored product beetles

The biological activity of camphor, a major component of essential oil of the basil shrub, Ocimum kilimandscharicum, against the beetles, Sitophilus granarius, S. zeamais, Tribolium castaneum and Prostephanus truncatus, was investigated in the laboratory using contact toxicity, grain treatment and repellency assays. Camphor applied either topically, impregnated on filter papers or whole wheat and maize grains was highly toxic to all the four species. Beetle mortality was dosage-dependent with the highest doses of 100 mg/ filter paper and 100 mug/insect evoking over 93% and 100% mortalities, respectively, in S. granarius, S. zeamais and P. truncatus after 24 h exposure. Similar doses induced 70% and 100% mortality in T. castaneum. Camphor impregnated on the grain surface was more effective than on filter paper. There was, however, highly significant reduction in toxicity in grain after only 24 h following treatment. Development of eggs and immature stages within grain kernels, as well as progeny emergence, was completely inhibited in camphor-treated grain. Camphor was also highly repellent to the beetles with overall repellency in the range of 80 - 100%. The potential use of suitable products derived from O. kilimandscharicum as supplementary or alternative grain protectants against insect damage in traditional grain storage in developing countries is discussed.     

The effects of temperature and humidity on the toxicity of three organophosphorus insecticides to adult Oryzaephilus surinamensis (L.)

The toxicities, to a laboratory susceptible strain and to a resistant strain of Oryzaephilus surinamensis (L.), of water-dispersible powder formulations of pirimiphos-methyl, fenitrothion or chlorpyrifos-methyl under constant conditions of 25°C and 70% r. h. were compared to the toxicities when the insects were exposed to a diurnal cycle of 12.5–20–12.5°C and 70–50–70% r. h. to simulate grain store conditions in the UK during spring and autumn. All the insecticides were more effective at 25°C and 70% r. h. The LD₅₀ values for the susceptible strain were low, being 4.4 and 1.4 mg m^?2 at 12.5-20°C and 25°C, respectively, for chlorpyrifos-methyl, 18.3 and 4.1 mg m^?2, respectively, for pirimiphos-methyl, and 4.0 and < 1.O mg m^?2, respectively, for fenitrothion. The LD₅₀ values obtained from the two sets of environmental conditions for a resistant strain (484) differed by factors of 1.8 for chlorpyrifos-methyl, 4.8 for pirimiphos-methyl, and 7.3 for fenitrothion. Toxicity studies were also made with chlorpyrifos-methyl under various constant conditions of temperature and humidity from 5–30°C (5°C intervals) and 30, 50, 70 and 90% r. h., and also at O°C and 60% r. h. Chlorpyrifos-methyl was very effective and there was little or no cross resistance to chlorpyrifos-methyl in the resistant strain. From 15 to 30°C, mortality was high, and differences in mortality at the LD₅₀ level for the various humidities were slight, but there was a decrease in mortality with decreasing humidity at any one temperature, in particular, at 5°C, 50 and 70% r. h., and 10°C and 50% r. h. Chlorpyrifosmethyl was more toxic to both strains at the highest humidity (90%) throughout the whole temperature range. The LD₅₀ values for each strain decreased at each temperature as the water vapour concentration was increased. At O°C and 60% r. h., all the insects from both strains died but the cause of death was not clear.     

An assessment of methacrifos as a grain protectant and its efficacy against oryzaephilus surinamensis L., Tribolium castaneum herbst,Sitophilus granarius L., Sitophilus oryzae L., Acarus siro L., Glycyphagus destructor schrank and Tyrophagus longior gervais

A trial was carried out to investigate the efficacy of methacrifos against susceptible and multi-resistant strains of four species of insect and three species of mite. Methacrifos was applied to two separate 20-tonne loads of English wheat which were then stored under ambient conditions for 24 weeks. The efficacy of methacrifos was assessed using established bioassay techniques which showed complete control for 24 weeks of all susceptible insects except S. oryzae, where there were survivors at week 24. Methacrifos also gave 100% mortality of resistant O. surinamensis for 24 weeks. There was >95% mortality for 16 weeks of resistant strains of T. castaneum and of resistant S. granarius and S. oryzae for 20 weeks. After S. granarius and S. oryzae were removed, the grain was incubated for 10 weeks. Subsequent F₁ emergence was considerably less from the treatments than from the controls. Methacrifos produced 100% mortality for T. longior for 24 weeks, but control of G. destructor fluctuated and was <100% at week 24. There were survivors of A. siro from week 4.     

Extensive pilot use of the grain protectant combinations,fenitrothion plus bioresmethrin and pirimiphos-methyl plus bioresmethrin

Each of the combinations, bioresmethrin (1 mg kg^?1) plus pirimiphos-methyl(6 mg kg^?1) or fenitrothion (12 mg kg^?1), was applied in 1976 to grain in 21 commercial storages. Grain condition and protectant residues were regularly monitored. Three storages became infested with Rhizopertha dominica (F.), but all storages remained free of other insect species. In two of the three infested storages, application of protectant was uneven, and the third became infested only after 8 months of storage. Despite some variations in recovered residues between sites, the mean residue levels were accurately described by predictive models. Falls in temperature during storage varied considerably, and were related to factors other than climate and bin size. There was a marked effect by aeration with ambient cold air on both the grain temperature and the rate of loss of residues. Results of collaborative studies on the determination of residues indicate a need for regular check programmes of analysis, and confirm previous conclusions that residues of fenitrothion and pirimiphos-methyl can be accurately and conventionally determined.     

Efficacy of grain protectants against four psocid species on maize,rice and wheat

BACKGROUND: Psocids are emerging pests in stored products, particularly in amylaceous commodities such as grains. Currently, their control is based on the use of fumigants and contact insecticides; however, newer data indicate that psocids are tolerant to insecticides used to control other stored‐grain species. This study evaluated the insecticides registered in the USA for use on stored maize, rice and wheat for control of the psocid species Lepinotus reticulatus, Liposcelis entomophila, L. bostrychophila and L. paeta. Mortality of exposed adult females was recorded after 7 and 14 days of exposure, while progeny production was assessed after 30 days of exposure. RESULTS: On wheat and rice, chlorpyriphos‐methyl + deltamethrin was generally more effective against exposed parental adults than spinosad or pyrethrin, while pirimiphos‐methyl was more effective on maize than spinosad or pyrethrin. In most cases, progeny production was suppressed in the treated grains. Progeny production was consistently lowest on wheat and rice treated with chlorpyriphos‐methyl + deltamethrin and maize treated with pirimiphos‐methyl. CONCLUSIONS: Chlorpyriphos‐methyl + deltamethrin and pirimiphos‐methyl were the most effective insecticides for all species and commodities. Conversely, efficacy of spinosad or pyrethrum was highly dependent on the psocid species and commodity. Published in 2009 by John Wiley & Sons, Ltd.     

9种农药对草地贪夜蛾的田间防治效果

选用9种药剂进行玉米草地贪夜蛾防治试验,结果表明,在供试的9种药剂及使用剂量中,14%氯虫苯甲酰胺高效氯氟氰菊酯SE 45 m L/667m²对草地贪夜蛾幼虫的防效较为稳定,持效期长;5%甲氨基阿维菌素WG 30 g/667m²、15%甲维·茚虫威SC 60 m L/667m²和10%甲维·虱螨脲SC 30 mL/667m²药后3 d的防效均达97%以上,具有很好的速效性。建议生产上可选择使用上述药剂。2种生物农药80亿孢子/mL金龟子绿僵菌CQMa421 OD和20亿PIB/mL甘蓝夜蛾核型多角体病毒SC,虽然速效性较差,但药后7～14 d,防效仍达83%以上,有较好的持效性,且对环境友好,不杀伤天敌,可在该虫的绿色防控中使用。在药剂中添加激健是否能显著提高药剂防效,以及是否可减少农药使用剂量还有待进一步研究。     

Effect of immigration time and beetle density on development of the cabbage stem flea beetle, (Psylliodes chrysocephala L.) and damage potential in winter oilseed rape

Journal of Plant Diseases and Protection - In a semi-field net cage experiment set up in three growing seasons (2015–2018) at Julius-Kühn Institute Braunschweig, Germany, the influence...     

Bioefficacy of compounds from Dittrichia viscosa (Asteraceae) as protectant of chickpea seeds against the cowpea seed beetle Callosobruchus maculatus (Coleoptera: Chrysomelidae)

Journal of Plant Diseases and Protection - The efficacy of four bi- and tri-cyclic sesquiterpenes, namely inuloxins A, B and C and α-costic acid, extracted from aerial parts of Dittrichia...     

Toxicity and protectant potential of Piper guineense (Piperaceae) and Senna siamea (Fabaceae) mixed with diatomaceous earth for the management of three major stored product beetle pests

There is a dearth of knowledge on the available sources of botanical products for smallholder farmers in Africa and their bioactivity against stored-product pests. Many locally available plants across Africa exhibit both promising insecticidal, medicinal activity and are nutrient rich yet remain underutilized. Laboratory studies on toxicity of powders of Senna siamea and Piper guineense alone or combined with diatomaceous earth (DE) to adult Sitophilus granarius, Tribolium castaneum and Acanthoscelides obtectus were conducted in stored grains. Adult mortality was observed up to 7 d while progeny production was recorded 6–10 weeks. Adult A. obtectus were most susceptible (LD₅₀ 0.0084% and 0.0696% wt/wt for S. siamea and P. guineense, respectively), followed by S. granarius. T. castaneum was most tolerant (LD₅₀ 0.6589% and 0.6829% wt/wt for S. siamea and P. guineense, respectively). Combination of plant powders and DE controlled the beetles faster compared to the plant powders alone. LT₅₀ ranged from 20 h to 101 h for T. castaneum exposed to 1.0% S. siamea and 1.0% DE, and 0.5% P. guineense and 1.0% DE, respectively. Botanicals caused significant reduction of F₁ adults compared to the control. The potential of using botanicals combined with DE to control stored-product insects is discussed.     

Biocontrol potential of Alternaria sp. PMK2, against a devastating weed: Parthenium hysterophorus L

Parthenium hysterophorus (Asteraceae) is known as one of the most aggressive invasive weeds, causing severe economic, environmental, human and animal health problems in India and around the world. During a series of extensive surveys for natural enemies of P. hysterophorus, a leaf spot pathogen was isolated from the affected parts of the parthenium following the standard isolation techniques using potato dextrose agar (PDA) and parthenium dextrose agar (PeDA) media. Koch's postulates were performed and found satisfactory for the isolate and proved to be pathogenic to this weed. On the basis of cultural, morphological and molecular characteristics, the pathogen was identified as Alternaria sp. PMK2. The growth of the pathogen was studied on eight selected media and it exhibited varying degrees of growth on different media. Phytotoxicity of fungal cultural filtrates was also confirmed on parthenium leaves in laboratory conditions. Due to the virulent nature of the isolated pathogen, it may be selected for further studies to develop mycoherbicide for control of this devastating weed.     

14种杀虫剂对草地贪夜蛾的杀卵活性

为筛选对草地贪夜蛾卵具有活性的杀虫剂,为防治卵期草地贪夜蛾提供数据支撑。采用浸渍法,室内测定了14种杀虫剂的杀卵活性。结果表明:14种杀虫剂均具有一定的杀卵活性。在100 mg/L浓度下,苯氧威、灭多威和吡丙醚的杀卵活性最强,显著高于其余药剂,且能够完全抑制卵的孵化。甲氨基阿维菌素苯甲酸盐(甲维盐)、氟虫脲、硫双威、氟铃脲、除虫脲和溴氰虫酰胺的杀卵效果无显著差异(P0.05),杀卵活性在71.67%～90.00%之间。在10 mg/L浓度下,苯氧威和吡丙醚杀卵活性最高,可完全抑制卵的孵化。甲维盐、除虫脲和溴氰虫酰胺也表现出较好的杀卵效果,杀卵活性介于55%～66.67%之间,以上药剂均可作为草地贪夜蛾的杀卵剂轮换使用。值得注意的是,茚虫威是一种对鳞翅目害虫具有优异杀虫活性的新型杀虫剂,且对环境友好。其在100 mg/L和10 mg/L处理浓度下对草地贪夜蛾杀卵活性为52.38%±6.25%和36.67%±6.67%。甲氧虫酰肼在两个处理浓度下的杀卵活性均低于30%,不推荐作为草地贪夜蛾的杀卵剂。上述结果可为草地贪夜蛾的有效防治提供参考。     

Biological activity of neem against the red pumpkin beetle,Aulacophora Foveicollis

The biological activity of neem on the red pumpkin beetle,Aulacophora foveicollis Lucas, was studied. The effective concentration for 50% antifeedant activity was 0.01% methanolic neem seed kernel extract (NSKE) and 0.4% neem oil, using leaves of muskmelon as feeding substrate. No-choice feeding of adults for a period of 11 days on leaves of muskmelon treated with 0.5-2.0% NSKE led to nearly 50% mortality within 4-7 days, whereas there was no mortality of adults fed on as high as 2% neem oil. The antifeedant activity of NSKE was found to vary with curcurbitaceous hosts. Neem oil as a residual film had an LC₅₀ of 0.7%. Unlike most chemical insecticides, 1% aqueous NSKE was not phytotoxic to the 5-day-old cotyledon stage and to 15- and 35-day-old crop stages of muskmelon, whereas 1% neem oil was toxic to the 5-day-old cotyledon stage and 15-day-old crop of muskmelon, but not to the 35-day-old crop.     

有机硅助剂对农药防治小菜蛾增效作用研究

对有机硅助剂混配农药防治小菜蛾的增效作用进行了研究。试验结果表明,有机硅助剂的使用,既可以提高4%～5%防治的效果,又可以减少农药用量。     

Efficacy of vaporised ethyl formate/carbon dioxide formulation against stored‐grain insects: effect of fumigant concentration,exposure time and two grain temperatures

BACKGROUND: The ethyl formate/carbon dioxide (CO₂) formulation Vapormate? is a rapid‐acting fumigant being developed for the control of stored‐grain insects. The effects have been investigated of concentration, exposure times of 1, 3, 24 and 72 h and two grain temperatures, 15 and 25 °C, on its efficacy against mixed‐stage cultures of Sitophilus oryzae (L.) Tribolium castaneum (Herbst) and strongly phosphine‐resistant Rhyzopertha dominica (F.) strain QRD569. RESULTS: High mortalities (≥92%) of mixed‐stage cultures of all three species were obtained when grain was fumigated with the formulation (193 g m^?3 ethyl formate) for 1 h. Complete control of R. dominica QRD569 and T. castaneum was achieved with 63 and 76 g m^?3 ethyl formate respectively, with exposure for 24 h, whereas mean mortality of S. oryzae was 86% under the same conditions. Mortalities of S. oryzae juvenile stages were significantly lower than adults under the conditions tested, which was due to pronounced tolerance of mid‐stage pupae to the fumigant. Reducing grain temperature from 25 to 15 °C had no effect on insect mortality. CONCLUSION: Ethyl formate/CO₂ formulation is highly effective against stored‐grain insects over a range of concentrations and exposure times. Efficacious fumigations were conducted in as little as 1 h, and a strongly phosphine‐resistant R. dominica strain was readily controlled with the fumigant. Copyright © 2009 CSIRO, Australia. Published by John Wiley & Sons, Ltd     

防治棉花黄萎病的生防细菌NCD-2的田间效果评价及其鉴定

 生防细菌NCD-2是自棉花根围土壤分离到的一株细菌菌株,田间小区试验表明:NCD-2菌株对棉花黄萎病的防治效果2年平均为85.4%,3年大区示范防病效果为51.2%~60.6%,并且该生防细菌对棉花产量和产量构成因子(单铃重、衣分、衣指、籽指等)及纤维品质(绒长)有所提高和改善。同时,本文测定了NCD-2对主要大田作物的安全性,证明其对小麦、玉米、棉花、马铃薯、黄瓜、茄子和大豆7种作物没有致病性,并且对这些作物的出苗、生长和发育没有不良影响。应用API50CH和API20 E细菌鉴定试剂盒,将NCD-2鉴定为枯草芽孢杆菌(Bacillus subtilis Cohn.)。     

4种杀虫剂对花生蛴螬的防治效果及农药残留研究

测定了35%辛硫磷微囊悬浮剂、25%毒死蜱微囊悬浮剂、10%二嗪磷颗粒剂、3%辛硫磷颗粒剂4种常用防治蛴螬杀虫剂在播种期和开花下针期使用对花生的保果效果和防虫效果。结果表明：25%毒死蜱微囊悬浮剂和35%辛硫磷微囊悬浮剂播种期使用的保果效果与防虫效果均优于开花下针期;而10%二嗪磷颗粒剂、3%辛硫磷颗粒剂开花下针期使用的保果效果和防虫效果均优于播种期。花生收获后对果仁的农药残留分析结果表明：在试验剂量下,各农药处理后花生仁中的农药残留水平均在0.01 mg/kg以下,符合日本肯定列表对各类农药残留限量的要求。     

Efficacy of dose-dependent indigenous microbial insecticides against cotton aphid,Aphis gossypii Glover (Homoptera: Aphididae) at various temperature regimes

Strain selection based on temperature may be warranted when choosing an isolate for development as a microbial control agent. To this end, the effects of three temperature regimes, namely 20, 25 and 30°C, on the virulence of four Beauveria and two Metarhizium isolates against the cotton aphid, Aphis gossypii, were investigated under controlled conditions, 65–70% relative humidity, and a photoperiod of 12:12 (light: dark) hours. The isolates did vary significantly in their activities of efficacy over a range of temperatures. The highest mortality and lowest survival times were observed at 25°C for DLCO41 and at 30°C for DLCO87; while mortality decreased and survival time increased at temperatures of 20°C. Besides the tested fungal isolate DLCO87 had the lowest LC₅₀ value (6.84 × 10⁵ conidia mL^?1) at 30°C. The promising result of this study should enable us to conduct further studies to determine the potential use of the fungus as an agent against Aphis gossypii both in greenhouse and under field conditions.