Efficacy of grain protectants against four psocid species onmaize, 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

Efficacy of layer treatment with methoprene for control of \u3ci\u3eRhyzopertha dominica\u3c/i\u3e (Coleoptera: Bostrychidae) on wheat, rice andmaize

BACKGROUND: Insect growth regulators are promising alternatives to traditional pesticides in stored grain. The efficacy of the juvenile hormone analogue methoprene was evaluated as a layer treatment in a laboratory experiment for control of Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) in wheat, rice and maize. RESULTS: Adults of R. dominica were placed in vials containing 33, 26 and 29 g (to a depth of 6.5 cm) of wheat, rice and maize, respectively, that was entirely or partially treated with 1, 5 or 10mg kg−1 methoprene. In wheat and rice, the layer treatments were not as effective as the whole-grain treatment, but there was decreased progeny production as the application rate increased. However, on maize the partial treatments were as effective as the whole-grain treatment at 5 and 10 mg kg−1. CONCLUSIONS: The results suggest that partial layer treatments with methoprene can be used to control R. dominica on maize but may not be effective for control of this species on wheat and rice

Effects of Short Exposures to Spinosad-Treated Wheat or Maize on Four Stored-Grain Insects

The effect of short exposures to spinosad-treated wheat, Triticum aestivum L., or maize, Zea mays L., was evaluated against adults of four stored-product insect species: lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae); rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae); red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae); and the psocid Lepinotus reticulatus (Enderlein) (Psocoptera: Trogiidae). Adult mortality of these species was recorded after 0, 2, 4, 8, 16, and 40 h on commodities treated with 1ppm of spinosad (immediate mortality). Then, the surviving individuals were removed and placed on untreated wheat or maize, and mortality was recorded again 7 d later (delayed mortality). Progeny production then was determined 65 and 35 d later for the beetles and psocids, respectively. Among the four species tested, R. dominica was the most susceptible, and immediate mortality after 40 h reached 78 and 72% on wheat and maize, respectively. Moreover, 7 d later, all adults that had been exposed for \u3e2 h were dead on both commodities. Progeny production was significantly reduced in comparison with the controls, and no progeny were found when parental adults had been exposed for \u3e8 or \u3e4 h on wheat and maize, respectively. For S. oryzae, 40-h exposures significantly increased delayed mortality on both wheat and maize, but progeny production still was high. Generally, no effect of short exposures was noted for T. castaneum. For L. reticulatus, despite the fact that the increase of exposure interval increased mortality on maize,progeny production was not avoided.With the exception of T.castaneum, more progeny were found on wheat than on maize. The results of the current study indicate that R. dominica is very susceptible after short exposures to spinosad-treated substrate, but the other species are able to survive and reproduce at the exposure range examined

Efficacy of Methoprene for Control of Five Species of Psocids (\u3ci\u3ePsocoptera\u3c/i\u3e) on Wheat, Rice, and Maize

The insect growth regulator methoprene was evaluated for control of Liposcelis bostrychophila Badonnel, Liposcelis decolor (Pearman), Liposcelis entomophila (Enderlein), Liposcelis paeta Pearman (Psocoptera: Liposcelididae), and Lepinotus reticulatus Enderlein (Trogiidae) at application rates of 1, 5, and 10 ppm on maize, wheat, and rice. Methoprene did not completely suppress progeny production during the 40-day test period, but did cause a significant reduction in adult progeny in all psocid species at the application rates of 5 and 10 ppm. At 1 ppm, numbers of adults were reduced for all species on wheat and maize, but only for L. paeta on rice. Nevertheless, the numbers of nymphs present after 40 days generally were not reduced, relative to the controls. Methoprene applied at rates of 1 to 10 ppm to stored grain would not provide adequate control of psocids

Advanced piezoresistance of extended metal/insulator core shell nanoparticle assemblies

Assembled metal/insulator nanoparticles with a core/shell geometry provide access to materials containing a large number (>106) of tunneling barriers. We demonstrate the production of ceramic coated metal nanoparticles exhibiting an exceptional pressure sensitive conductivity. We further show that graphene bi- and trilayers on 20 nm copper nanoparticles are insulating in such core/shell geometry and show a similar pressure dependent conductivity. This demonstrates that core/shell metal/insulator assemblies offer a route to alternative sensing materials.Comment: 14 pages, 3 figures, published in Physical Review Letter

Lesser grain borers, \u3ci\u3eRhyzopertha dominica\u3c/i\u3e, select rough rice kernels with cracked hulls for reproduction

Tests were conducted to determine whether the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), selects rough rice (Oryza sativa L. (Poales: Poaceae)) kernels with cracked hulls for reproduction when these kernels are mixed with intact kernels. Differing amounts of kernels with cracked hulls (0, 5, 10, and 20%) of the varieties Francis and Wells were mixed with intact kernels, and the number of adult progeny emerging from intact kernels and from kernels with cracked hulls was determined. The Wells variety had been previously classified as tolerant to R. dominica, while the Francis variety was classified as moderately susceptible. Few F1 progeny were produced in Wells regardless of the percentage of kernels with cracked hulls, few of the kernels with cracked hulls had emergence holes, and little frass was produced from feeding damage. At 10 and 20% kernels with cracked hulls, the progeny production, number of emergence holes in kernels with cracked hulls, and the amount of frass was greater in Francis than in Wells. The proportion of progeny emerging from kernels with cracked hulls increased as the proportion of kernels with cracked hulls increased. The results indicate that R. dominica select kernels with cracked hulls for reproduction

Biodegradable All-Polymer Field-Effect Transistors Printed on Mater-Bi

The growing demand of disposable electronics raises serious concerns for the corresponding increase in the amount of electronic waste, with severe environmental impact. Organic and flexible electronics have been proposed long ago as a more sustainable and energy-efficient technological platform with respect to established ones. Yet, such technology is leading to a drastic increase of plastic waste if common approaches for flexible substrates are followed. In this scenario, biodegradable solutions can significantly limit the environmental impact, actively contributing to eliminate the waste streams (plastic or electronic) associated with disposal of devices. However, achieving suitably scalable processes to pattern mechanically robust organic electronics onto largely available biodegradable substrates is still an open challenge. In this work, all-organic and highly flexible field-effect transistors, inkjet printed onto the biodegradable and compostable commercial substrate Mater-Bi, are demonstrated. Because of the thermal instability of Mater-Bi, no annealing steps are applied, producing devices with limited carrier mobility, yet showing correct n-type behavior and robustness to bending and crumpling. The degradation behavior of the final system shows unaltered biodegradability level according to ISO 14851. These results represent a promising step toward sustainable flexible and large-area electronics, combining energy and materials efficient processes with largely available biodegradable substrates

Residual Efficacy of Chlorfenapyr for Control of Stored-Product Psocids (Psocoptera)

The residual effect of chlorfenapyr (Phantom) was evaluated for residual control of three stored-product psocid species: Liposcelis bostrychophila Badonnel, Liposcelis entomophila (Enderlein), and Liposcelis paeta Pearman (Psocoptera: Liposcelididae). Chlorfenapyr was applied to individual arenas with a concrete surface at rates of 0, 2.8, 13.8, 20.6, 27.5, 55, and 110 mg active ingredient (AI)/m2. Adults were exposed on the treated arenas and mortality assessed after 1, 2, and 3 d. The procedures were repeated weekly on the same treated arenas for 3 wk to assess residual efficacy. At each week, mortality of all species was low after 1 d of exposure but notably increased after 2 or 3 d. L. entomophila was the most susceptible species, with 99-100% mortality at rates of 13.8 mg/m2 or higher. Similarly, mortality of L. paeta after 3 d of exposure at the same concentration ranged from 92 to 100%. L. bostrychophila was the least susceptible species, with mortality of \u3c60% during the third week after application at rates ≤27.5 mg/m2. However, even for this species, mortality after 3 wk was 90% or higher at rates \u3e27.5 mg/m2. Complete mortality of all species occurred after 3 d exposure at the highest rate tested of 110 mg/m2. Thus, our results show that chlorfenapyr is effective against major psocid species at the application rates evaluated in this study

Insecticidal Effect of Diatomaceous Earth Against Three Species of Stored-Product Psocids on Maize, Rice, and Wheat

We evaluated the efficacy of three diatomaceous earth (DE) formulations, Dryacide, Protect-It, and Insecto, against three Psocoptera species, Liposcelis entomophila (Enderlein) (Liposcelididae), Lepinotus reticulatus Enderlein (Trogiidae), and Liposcelis decolor (Pearman), in the laboratory. Bioassays were conducted in three grain commodities, wheat, rice and maize, at 30°C and 75% RH, and the DEs were applied at the recommended dose rates of 1,000, 400, and 500 ppm for Dryacide, Protect-It, and Insecto, respectively. Differences in adult mortality were found among grains and DEs for L. entomophila and L. reticulatus, but these trends were not consistent for all combinations tested. Type of grain and DE did not affect L. decolor mortality significantly. Moreover, mortality increased with increasing exposure time for L. entomophila and L. reticulatus, but there was no effect of exposure time on L. decolor. After 7 d of exposure, mortalities of L. entomophila, L. reticulatus, and L. decolor were 56, 55, and 40%, respectively, and the respective mortality levels after 14 d were 63, 71, and 42%. Progeny production after 30 d was significantly suppressed for all species in the treated grains. However, progeny production was still high in the treated grains and reached 54, 42, and 76 individuals/10 g of grain for L. entomophila, L. reticulatus, and L. decolor, respectively. Progeny production did not vary with commodity. Our results suggest that DEs, when used alone, will not provide effective control of psocids