Persistence and efficacy of spinosad residues in farm stored wheat

Degradation and insecticidal effectiveness of spinosad residues were evaluated in Kansas during November 2000 to November 2001 in farm bins holding wheat (34-metric ton capacity). About 50 kg of hard red winter wheat from each of three bins were brought to the laboratory and treated separately with 1-ml aqueous suspensions of spinosad to provide rates of 0.1, 0.5,1, 3, 6 mg (AI)/kg of wheat. Wheat treated with distilled water served as the control treatment. Untreated and spinosad-treated wheat samples (250 g each) were placed in three plastic pouches of two different mesh sizes, and buried 2.5 cm below the grain surface. Pouches with large mesh openings were used to monitor insect infestations and kernel damage in untreated and spinosad-treated samples. Pouches with small mesh were used for extracting spinosad residues and for conducting laboratory bioassays with adults of the lesser grain borer, Rhyzopertha dominica (F.) and red flour beetle, Tribolium castaneum (Herbst) at 28 degrees C and 65% RH. Wheat temperature and relative humidity near the pouches during the 1 yr of storage ranged from -10 to 32 degrees C and 50 to 70%, respectively. Moisture of wheat samples varied from 12.4 to 13%. Observed spinosad residues on wheat samples were 25% less than the calculated rates of 0.1 to 6 mg/kg. However, these residues were stable during the 1 yr of storage, and killed all R. dominica adults exposed for 14 d in the laboratory. Mortality of T. castaneum adults increased with an increase in spinosad rate. The linear regression slope of LD50s (0.3-2.7 mg/kg) against storage time was not significantly different from zero, indicating no loss in spinosad toxicity to T. castaneum adults. Insect species, insect numbers, and kernel damage over time in wheat samples inside pouches with large mesh openings were highly inconsistent, and failed to accurately characterize spinosad performance. Laboratory bioassays with R. dominica and T castaneum adults using grain from pouches with small mesh openings accurately gauged spinosad persistence and insecticidal activity under the field conditions.     

Spatial associations of insects and mites in stored wheat

The spatial association pattern of insect and mite populations in a steel bin containing stored wheat, Triticum durum Desf., in central Greece, was studied using the Spatial Analysis by Distance IndicEs (SADIE). The monitoring was carried out for 7 mo by using grain trier samples and probe traps. The most abundant insect species were Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae) and Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae). For mites, the most abundant species were the phytophagous Lepidoglyphus destructor (Schrank) (Acari: Glycyphagidae) and the predator Blattisocius tarsalis (Berlese) (Mesostigmata: Ascidae). Both for P. interpunctella and C. ferrugineus, trap catches were associated with numbers of individuals in the trier samples, but the overall association index calculated among trap and sample counts was significant only in the 33% of trap-sample pairs of values. Generally, P. interpunctella had the main patch areas in the central part of the bin, with few exceptions, during the entire monitoring period. Similar trends also were noted in the case of C. ferrugineus, which was clearly aggregated in the center of the grain mass. Spatial association maps indicated a stable positive association in the central part of the bin, but in most of the other sampling zones the association was negative. However, distribution of L. destructor, based on trier samples, indicated increased presence in peripheral zones of the grain sampling area. Moreover, B. tarsalis presented the most dispersed distribution among all four species. For each species, the association between two consecutive samplings was significant in the majority of cases, indicating a stable spatial pattern. Finally, B. tarsalis was spatially associated to a higher degree with the insects found rather than with L. desctructor. Moreover, there was no association of insect and mite presence with grain temperature and moisture content. The results of the current study suggest that the coexistence of insects and mites in bulked grain follows a complex pattern, with significant interactions, especially in the case of mite predators, which are spatially associated with insect species.     

Spatiotemporal distribution of insects and mites in horizontally stored wheat

Samples were taken from a flat storage facility located in central Greece, filled with approximately 45 tons of hard wheat, to assess the spatiotemporal distribution of stored-product insects and mites. The wheat was stored in a 1.5-m-deep bulk from June 2001 until March 2002. The samples were taken with a partitioned grain trier during the entire storage period, at 10-d intervals. The trier samples were examined separately for the upper, medial, and lower 0.5 m of the bulk. The spatial distribution of the insect and mite species found was examined by contour analysis based on the numbers of individuals in the trier samples. Nine insect and 20 mite taxa were found during the sampling period. The most abundant insect species were Tribolium castaneum (Herbst), Cryptolestes ferrugineus (Stephens), and Rhyzopertha dominica (F.); the most abundant mite species were Lepidoglyphus destructor (Schrank), Acarus siro L., and the predator Cheyletus malaccensis Oudemans. The highest population densities for the majority of the insect and mite species were recorded during autumn. The majority of the individuals of the most abundant insect and mite species were found in the upper 0.5 m of the bulk, with the exception of C. malaccensis, which was equally distributed in the upper and medial 0.5 m of the bulk. The spatiotemporal distribution during the entire experimental period was notably varied according to the insect and mite species.     

Effectiveness of spinosad on four classes of wheat against five stored-product insects

Spinosad is a commercial reduced-risk pesticide that is naturally derived. Spinosad's performance was evaluated on four classes of wheat (hard red winter, hard red spring, soft red winter, and durum wheats) against adults of the lesser grain borer, Rhyzopertha dominica (F.); rice weevil, Sitophilus oryzae (L.); sawtoothed grain beetle, Oryzaephilus surinamensis (L.); red flour beetle, Tribolium castaneum (Herbst); and larvae of the Indianmeal moth, Plodia interpunctella (Hübner). Beetle adults (25) or P. interpunctella eggs (50) were exposed to untreated wheat and wheat treated with spinosad at 0.1 and 1 mg (AI)/kg of grain. On all untreated wheat classes, adult beetle mortality ranged from 0 to 6%, and P. interpunctella larval mortality ranged from 10 to 19%. The effects of spinosad on R. dominica and P. interpunctella were consistent across all wheat classes. Spinosad killed all exposed R. dominica adults and significantly suppressed progeny production (84-100%) and kernel damage (66-100%) at both rates compared with untreated wheat. Spinosad was extremely effective against P. interpunctella on all wheat classes at 1 mg/kg, based on larval mortality (97.6-99.6%), suppression of egg-to-adult emergence (93-100%), and kernel damage (95-100%), relative to similar effects on untreated wheats. The effects of spinosad on S. oryzae varied among wheat classes and between spinosad rates. Spinosad was effective against S. oryzae, O. surinamensis and T. castaneun only on durum wheat at 1 mg/kg. Our results suggest spinosad to be a potential grain protectant for R. dominica and P. interpunctella management in stored wheat.     

Pyrethroid-Acarophenax lacunatus interaction in suppressing the beetle Rhyzopertha dominica on stored wheat

Any biocontrol agent used against stored grain insects will have to interact with insecticides used as grain protectants due to their heavy use especially in tropical areas. Therefore, the interaction between the pyrethroid insecticides bifenthrin and deltamethrin and Acarophenax lacunatus (Cross & Krantz) (Prostigmata: Acarophenacidae), an egg parasite of the stored cereal pest Rhyzopertha dominica(F.) (Coleoptera: Bostrichidae), was assessed in a range of mite densities and insecticide doses for each compound. Despite the mite species presence on all insecticide doses, the lowest instantaneous rate of increase of A.lacunatus was recorded with the highest doses of insecticides. The presence of the biological control agent at all doses of both insecticides suggests its tolerance to these compounds. A. lacunatusshowed higher parasitism rate with bifenthrin than with deltamethrin indicating a higher selectivity of the first compound to the biocontrol agent. This revised version was published online in August 2006 with corrections to the Cover Date.     

Field evaluation of spinosad as a grain protectant for stored wheat in Australia: efficacy against Rhyzopertha dominica (F.) and fate of residues in whole wheat and milling fractions

Abstract  The potential of spinosad as a grain protectant for the lesser grain borer, Rhyzopertha dominica , was investigated in a silo-scale trial on wheat stored in Victoria, Australia. Rhyzopertha dominica is a serious pest of stored grain, and its resistance to protectants and the fumigant phosphine is becoming more common. This trial follows earlier laboratory research showing that spinosad may be a useful pest management option for this species. Wheat (300 t) from the 2005 harvest was treated with spinosad 0.96 mg/kg plus chlorpyrifos-methyl 10 mg/kg in March 2006, and samples were collected at intervals during 7.5 month storage to determine efficacy and residues in wheat and milling fractions. Chlorpyrifos-methyl is already registered in Australia for control of several other pest species, and its low potency against R. dominica was confirmed in laboratory-treated wheat. Grain moisture content was stable at about 10%, but grain temperature ranged from 29.3°C in March to 14.0°C in August. Bioassays of all treated wheat samples over 7.5 months resulted in 100% adult mortality after 2 weeks exposure and no live progeny were produced. In addition, no live grain insects were detected during outload sampling after a 9 month storage. Spinosad and chlorpyrifos-methyl residues tended to decline during storage, and residues were higher in the bran layer than in either wholemeal or white flour. This field trial confirmed that spinosad was effective as a grain protectant targeting R. dominica .     

Effectiveness of spinosad against seven major stored-grain insects on corn

In January 2005, the United States Environmental Protection Agency registered spinosad as a stored grain protectant. No referenced data on the efficacy of spinosad on corn in suppressing major stored-grain insects have been published. In this paper, we evaluated the efficacy of spinosad against seven major stored-grain insects on shelled corn in the laboratory. Insect species tested were the red flour beetle, Tribolium castaneum （Jacquelin duVal）; rusty grain beetle, Cryptolestesferrugineus （Stephens）; lesser grain borer, Rhyzopertha dominica （F.）; sawtoothed grain beetle, Oryzaephilus surinamensis （L.）; rice weevil, Sitophilus oryzae （L.）; maize weevil, Sitophilus zeamais （Motschulsky）; and Indian meal moth, Plodia interpunctella （Htibner）. Corn kernels were treated with spinosad at 0, 0. 1, 0.5, 1, and 2 active ingredient （a.i.） mg/kg for controlling the seven species. Beetle adults or P. interpunctella eggs were introduced into each container holding 100 g of untreated or insecticide-treated corn. The seven insect species survived well on the control treatment, produced 28 to 336 progeny, and caused significant kernel damage after 49 days. On spinosad-treated corn, adult mortality of C. ferrugineus, R. dominica, 0. surinamensis, S. oryzae, and S. zeamais was 〉 98% at 1 and 2 mg/kg after 12 days. Spinosad at≥ 0.5 mg/kg completely suppressed egg-to-larval survival after 21 days and egg-to-adult emergence of P. interpunctella after 49 days, whereas 16% T. castaneum adults survived at 1 mg/kg after 12 days. Spinosad at 1 or 2 mg/kg provided complete or near complete suppression of progeny production and kernel damage of all species after 49 days. Our results indicate that spinosad at the current labeled rate of 1 mg/kg is effective against the seven stored-grain insect pests on corn.     

Use of a web-based model for aeration management in stored rough rice

A web-based model was used to simulate the impact of aeration on population growth of the lesser grain borer, Rhyzopertha dominica (F.), and the rice weevil, Sitophilus oryzae (L.), in stored rough rice, Oryza sativa L., at Beaumont, TX. Simulations were run for each of 10 yr with 1 August as the start date; 31 December as the end date; beginning populations of 2.5 adults per metric ton (1000 kg); starting grain temperatures of 29.4, 32.2, and 35.0 degrees C; and aeration airflow rates of 0.27, 0.79, and 1.40 m3/min/metric ton of rice. In the absence of aeration, populations of both species increased exponentially, with maximum production of R. dominica and S. oryzae at starting grain temperatures of 35.0 and 32.2 degrees C, respectively. Final predicted populations of R. dominica on 31 December from grain starting temperatures of 29.4, 32.2, and 35.0 degrees C were 5465, 6848, and 11,855 per ton, respectively; final predicted populations of S. oryzae were 13,288, 21,252 and 4355, respectively. Aeration led to a reduction in grain temperature and a decrease in pest populations, regardless of starting grain temperature or aeration airflow rates. Predicted populations of R. dominica on 31 December ranged from 12 to 63 adults per ton at all grain starting temperatures and airflow rates; populations of S. oryzae on 31 December ranged from 108 to 193 adults per ton at all grain starting temperatures and airflow rates. The predicted population levels in aerated rice represented at least a 98% reduction compared with unaerated rice. Results show the utility of the web-based model and how the various model inputs can help define broader patterns of insect control in rice stored in the south central United States.     

气调(CA)对储藏物害虫的作用机制

本文系统地介绍了气调措施对储藏物害虫的作用机制。在气调环境中 ,高CO2 和低O2 迫使昆虫的气门开启 ,导致体内水分过多散失和神经麻痹 ;吸入昆虫体内的CO2 能抑制昆虫的有氧代谢 ,导致昆虫体内能源物质的耗尽和有毒物质的积累。此外 ,气调还可导致储藏物害虫一些行为习性上的改变。     

储粮环境挥发性化合物与储粮害虫的关系研究进展

每种粮食的储粮环境中都存在有其特征性挥发物,储粮害虫的发生对储粮环境中挥发物具有重要影响。本文简述了顶空式固相微萃取法、浸入式固相微萃取法、电子鼻检测法等储粮挥发物的提取方法及其优缺点,对小麦 Triticum aestivum L.、稻谷 Olyza sativa L.、玉米 Zea mays L.和燕麦 Avena sativa L.等主要储藏粮食种类的挥发性化合物成分、粮食挥发物对昆虫行为反应的影响、主要储粮害虫(赤拟谷盗 Tribolium castaneum、锈赤扁谷盗 Cryptolestes ferrugineus 和象虫 Sitophilus spp.)发生与粮食挥发物的关系等研究进展进行综述,探讨了储粮环境挥发性化合物与储粮害虫关系未来的研究方向,以期对今后储粮害虫生态防治研究与应用提供参考信息。     

Efficacy of ethiprole applied alone and in combination with conventional insecticides for protection of stored wheat and stored corn

The insecticidal pyrazole ethiprole, applied at rates of 7.5 and 10.0 ppm either alone or in combination treatments with deltamethrin, piperonyl butoxide, and chlorpyrifos-methyl, was evaluated as a protectant of stored wheat and stored corn. The commodities were treated with six treatment combinations, including an untreated control, and held for 6 mo at 22, 27, or 32 degrees C and 57% RH. Bioassays were conducted monthly by exposing the rice weevil, Sitophilus oryzae (L.), and the red flour beetle, Tribolium castaneum (Herbst), on treated wheat and the maize weevil, Sitophilus zeamais (Motschulsky), and the red flour beetle on treated corn. The storage temperature of wheat did not significantly affect mortality of exposed insects (P > or = 0.05). All rice weevils were dead after 1 wk in all treatments, and no F1 adults were produced. Mortality of red flour beetles was not dependent on either chemical treatment or bioassay month, and no F1 adults were produced. The storage temperature of corn did not significantly affect mortality of exposed insects (P > or = 0.05). Mortality of maize weevils varied from 77.9 to 100% in all chemical treatments, and no F1 adults were produced. Mortality of red flour beetles was also variable among treatments and bioassay month and no F1 adults were produced. This is the first published report of a study in which pyrazoles have been evaluated against stored-grain insects.     

Monitoring of wheat insects and their natural enemies using sticky traps in wheat

Beneficial arthropods and wheat insects were monitored using sticky traps through large-scale field in Saxony, Germany before and after insecticide applications. The tested compounds (Karate, Biscaya and NeemAzal T/S) were sprayed twice at Elongation stage (GS 32) and at the heading stage (GS 55). Monitoring was conducted for four weeks after each treatment. Cereal aphids, thrips, leafhoppers, cereal leaf beetles, cereal bugs and also many natural enemies such as predators (lady beetles, lacewings, syrphids, dance flies and spiders) and parasitoids (parasitic wasps) were surveyed. The results proved that Karate caused the highest per cent mortality to wheat insect pests. Karate also reduced natural enemy diversities. Biscaya and NeemAzal T/S is correlated with an equivalent mortality per cents to wheat insect pests and resulted in a smaller effects on natural enemies compared with Karate. Leafhoppers were less affected than Thrips and cereal bugs. Parasitoid wasps and spider were more tolerant, while lacewings and dance flies were more susceptible to insecticide effects. Finally, natural insecticides and predators and parasitoids could be highly compatible with a hygienic environment.     

Biological,physical and chemical changes in stored wheat

Six lots of wheat from six farmers' bins in Manitoba were adjusted to a range of 5 moisture contents, held at 6 temperatures and sampled at 6 times during storage. After sampling, seeds were surface sterilized with mercuric chloride and subsamples plated on Czapek's agar, on filter paper moistened with water, or on filter paper moistened with a 7.5% sodium chloride solution. The microflora on the seed was determined, germination counts were made, and the seed was examined by government inspectors for its condition and grade. A total of 1192 samples were examined. In addition, 180 samples were subjected to a fat acidity test. Deterioration for each combination of temperature and moisture, the fungi involved, and the consequent effect on condition, grade and fatty acid content were observed. The effect of high moisture content (>20%) and low temperatures (3–10 ° C) on infection of seed by Penicillium and the consequent effect on germination, condition, grade and fatty acid value are stressed. The interrelationship among fungi, and among fungi and temperature, moisture, storage time, fat acidity values and germination are indicated by correlation coefficient matrices.Deceased July 25, 1982.     

我国仓储昆虫研究和防治的回顾与展望

与人类生活和经济发展密切相关的各类农产品,在其储藏期间和加工过程中常遭受仓储昆虫的严重为害。至今全世界已记载的仓储昆虫和螨类约500种,我国有383种,其中仓储昆虫242种,螨类141种。昆虫和螨类二者在储藏物中的栖境、食性和危害性基本相似,因此常通称为仓储害虫。它们多数潜藏在仓库、厂房、贷栈、商店、居室、图书馆、档案馆等处,为害储藏粮食、油料、动植物食品、中药材、烟草、棉、麻、丝、皮毛、呢料、图书、档案、纸质文物、竹木及其制品、电缆、塑料以及进出口贸易中的检疫商品等,造成很大损失。如粮油储藏期每年因虫害损…     

麦田昆虫群落结构和变动的研究

通过田间调查,在Windows 98平台上利用Visual Basic6.0统计编程,系统研究了麦田害虫及其天敌从5月9日至6月2日的相对多度、物种丰富度、生态优势度、多样性指数和均匀度的变动。表明5麦田是相继作物害虫的重要天敌源,应保护利用。     

Insect infestation of stored oats in Florida and field evaluation of a device for counting insects electronically

Automated methods of monitoring stored grain for insect pests will contribute to early detection and aid in management of pest problems. An insect population infesting stored oats at a seed processing plant in north-central Florida was studied to test a device for counting insects electronically (Electronic Grain Probe Insect Counter, EGPIC), and to characterize the storage environment. The device counts insects as they fall through an infrared beam incorporated into a modified grain probe (pitfall) trap and transmits the counts to a computer for accumulation and storage. Eight traps were inserted into the surface of the grain bulk, and the insects trapped were identified and counted manually at weekly intervals. Grain temperature and moisture content also were recorded for each trap location. Manual and automatic counts were compared to estimate error in the EGPIC system. Both over- and undercounting occurred, and errors ranged from -79.4 to 82.4%. The mean absolute value of error (+/- SE) was 31.7% (+/- 4.3). At least 31 species, or higher taxa, were detected, but the psocid Liposcelis entomophila (Enderlein) and the foreign grain beetle, Ahasverus advena (Waltl), accounted for 88% of the captured insects. Species diversity, phenology, and spatial distribution are presented, as well as temporal and spatial distribution of grain temperature and moisture content. The data sets generated will find application in population modeling and development of integrated pest management systems for stored grain.     

Genetic approaches to reducing losses of stored grain to insects and diseases

Insects and diseases devour or damage a fifth or more of stored food grains each year in many parts of the world. Modern breeding and genomics promise progress in characterizing the resistance to the pests responsible for these losses that is present in the vast and diverse gene pool of cereals, as well as advances in incorporating this resistance into productive and acceptable crop varieties. The impact of such varieties could be dramatic in developing countries, where grain infestations are most common and harmful, and where surging populations require affordable food.