Distribution of psocids (Psocoptera) in temperature gradients in stored wheat

Psocids have become important pests of stored products during the last two decades, but little is known about their behavior or ecology. We examined distribution of Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae), Liposcelis entomophila (Enderlein), and Liposcelis paeta (Pearman), three of the main psocid pests of stored grain throughout the grain growing regions of the world, in temperature gradients of 20°-24°C, 20°-30°C, and 20°-42°C in small bulks of wheat to determine their ecological preferences. Psocids consistently preferred the warmest regions of the gradients, except in the 20-42°C gradients. Over 80 and 78% of psocids moved to the warmest region of the grain in the 20°-24° and 20°-30° gradients, respectively. Liposcelis bostrychophila females and both sexes of L. paeta preferred the warmer region of the grain in the 20°-42° gradient, while densities of L. entomophila males were higher in more moderate temperature regions of the grain and densities of L. entomophila females were evenly split between the warm and hot regions of the grain. Temperatures can be below 20°C during much of the storage season for grains, so the current results help to explain why psocids move to warmer regions of the grain which occur toward the center of the grain mass as grain temperatures cool in the fall. This may allow psocid populations to continue to grow during the colder months

Should Grain Elevator Managers Adopt Integrated Pest Management?

Insect infestation during storage and processing causes millions of dollars of wheat damage annually in the United States. Insect infestation reduces wheat storing processing profit as well as consumer confidence in wheat food products. Meanwhile, increased concerns about insecticide use have increase interest in Integrated Pest Management (IPM) strategies. This research compares the costs of IPM and chemical-based approaches to insect control to determine why most elevator managers have not adopted IPM practices.Agribusiness,

Freezing for control of stored-product psocids

A series of studies was conducted by exposing young and old eggs, nymphs, and adults of the psocids Liposcelis bostrychophila (Badonnel), L. paeta (Pearman), L. decolor (Pearman), and L. entomophila (Enderlein) to -18°C for various time intervals. Survival was assessed as initial and final, at different times depending on the life stage. Young eggs of L. bostrychophila were the most tolerant life stage of any of the species, with scattered survival out to 120 h of exposure to -18°C. Eggs were the most tolerant life stage for each species, requiring 24, 12, and 2 h of exposure for complete kill of L. paeta, L. decolor, and L. entomophila, respectively. Nymphs and adults of all species were far more susceptible than eggs, with no final survival after two hours of exposure. Results show the extreme variation between different psocid life stages and species to cold temperatures, and provide guidelines for using cold as a control strategy for psocids. Our results show that 24 h at -18°C is sufficient to kill all life stages of the psocid species tested, except for young L. bostrychophila eggs which will require at least 128 h of exposure at -18°C for complete mortality

Distribution of three psocid species (Psocoptera: Liposcelididae) in different moisture gradients in wheat

Psocids can cause considerable economic losses to stored products by direct feeding, and they have become global pests during the last two decades. We studied the distribution of Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae), Liposcelis entomophila (Enderlein), and Liposcelis brunnea Motschulsky in different moisture gradients (11-12-13%, 11-13-15%, and 13-14-15%) and a control (13-13-13%) in wheat using a circular metal arena, which has a removable metal divider that partitioned it into three rings (outer, middle and inner). Lipsocelis bostrychophila and L. entomophila preferred grain with the highest moisture content in the different gradients evaluated. In general, populations of Liposcelis brunnea equally preferred grain with moisture contents greater than or equal to 13%. These results showed the moisture contents preferred for three of the main psocid pests of stored grains, and this could help in making better pest management decisions

Detection of Stored-Grain Insect Infestation in Wheat Transported in Railroad Hopper-Cars

Levels of insect infestation, insect spatial distribution, and the relationship between the number of insect-damaged kernels (IDK) and the number of insects present in grain samples in three-hopper railcars transporting wheat from country elevators to a mill were studied. Six of eight sampled railcars were infested with more than two species of insects. The most abundant species collected were the lesser grain borer, Rhyzopertha dominica (F.), and rusty grain beetle, Cryptolestes ferrugineus (Stephens), with the larval stage of the two species being the most prevalent (\u3e90%). The spatial distributions of these two species within the grain mass were typically clumped in railcar compartments containing\u3e0.4 insect/2.75-kg sample of wheat, and these foci of high-infestation levels varied in compartments within the railcars and among the sampled railcars. There were no significant correlations between IDK and insect density for any of the different stage-specific insect populations that were collected in the grain samples. Mean numbers of immatures and IDK differed among railcars and compartments within railcars, but not among grain depths. Number of insects in the first discharge sample was not correlated with mean numbers of insects in the entire compartment. This indicates that each compartment of a railcar should be sampled to determine level of insect infestation but that sampling at different depths within a compartment is less important

Detection of Stored-Grain Insect Infestation in Wheat Transported in Railroad Hopper-Cars

Levels of insect infestation, insect spatial distribution, and the relationship between the number of insect-damaged kernels (IDK) and the number of insects present in grain samples in three-hopper railcars transporting wheat from country elevators to a mill were studied. Six of eight sampled railcars were infested with more than two species of insects. The most abundant species collected were the lesser grain borer, Rhyzopertha dominica (F.), and rusty grain beetle, Cryptolestes ferrugineus (Stephens), with the larval stage of the two species being the most prevalent (\u3e90%). The spatial distributions of these two species within the grain mass were typically clumped in railcar compartments containing\u3e0.4 insect/2.75-kg sample of wheat, and these foci of high-infestation levels varied in compartments within the railcars and among the sampled railcars. There were no significant correlations between IDK and insect density for any of the different stage-specific insect populations that were collected in the grain samples. Mean numbers of immatures and IDK differed among railcars and compartments within railcars, but not among grain depths. Number of insects in the first discharge sample was not correlated with mean numbers of insects in the entire compartment. This indicates that each compartment of a railcar should be sampled to determine level of insect infestation but that sampling at different depths within a compartment is less important

Variable Curvature Slab Molecular Dynamics as a Method to Determine Surface Stress

A thin plate or slab, prepared so that opposite faces have different surface stresses, will bend as a result of the stress difference. We have developed a classical molecular dynamics (MD) formulation where (similar in spirit to constant-pressure MD) the curvature of the slab enters as an additional dynamical degree of freedom. The equations of motion of the atoms have been modified according to a variable metric, and an additional equation of motion for the curvature is introduced. We demonstrate the method to Au surfaces, both clean and covered with Pb adsorbates, using many-body glue potentials. Applications to stepped surfaces, deconstruction and other surface phenomena are under study.Comment: 16 pages, 8 figures, REVTeX, submitted to Physical Review

The Small Politics of Everyday Life: Local History Society Archives and the Production of Public Histories

Thousands of small, private archives sit in attics, cupboard, church halls and computer hard drives around the country; they are the archives of local history societies. Simultaneously freed from the control of archives sector and government initiatives, and yet saturated with local peculiarities and biases, local history society archives can seem to be the very antithesis of the wider archives movement, apparently private and parochial, undemocratic and uncatalogued. Consequently, local history society archives are rarely included in ‘the politics of the archive’ discussions. But if the activity of archiving is to be understood as a political act, what are the politics and meanings of local history and their archives? In this article, I suggest that certain types of local history society archive collections can help us paint a picture of the everyday lives of working-class people in Britain in the twentieth century. They detail the small politics of people’s lives – family, work, leisure, and beliefs. They give ordinary people a name, a face, and a life lived. Moreover, the workings of local history society archives raise important questions about historical production, for these groups play a significant role in rescuing and preserving archival collections, and in creating and curating their own histories

Just do it

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28510/1/0000307.pd

Effects of Intra- and Interpatch Host Density on Egg Parasitism by Three Species of Trichogramma

Host-foraging responses to different intra- and interpatch densities were used to assess three Trichogramma spp. (Hymenoptera: Trichogrammatidae) Trichogramma deion Pinto and Oatman, T. ostriniae Pang and Chen, and T. pretiosum Riley — as potential biological control agents for the Indian meal moth, Plodia interpunctella Hübner (Lepidoptera: Pyralidae). Single naïve females were allowed 6 h to forage in Plexiglas arenas with four different spatial arrangements of host eggs, nine single-egg patches), nine four-egg patches, 36 single-egg patches, and 36 four-egg patches. No significant differences were found among species in the number of patches parasitized. As expected, all three species parasitized the most eggs in the 36 four-egg patch treatment and the least in the nine single-egg patch treatment. T. deion parasitized significantly more eggs than T. pretiosum on the nine four-egg patches. T. ostriniae parasitized significantly more patches when intrapatch density was greater, regardless of interpatch density. In contrast, T. deion only parasitized more patches at the greater intrapatch density when the interpatch density was low. Patch density had no effect on T. pretiosum. The spatial pattern of parasitism was more aggregated for T. deion and T. ostriniae in the 36 four-egg patches treatment compared to the 36 single-egg patches treatment. Therefore, intrapatch density was more important than interpatch density for T. ostriniae, and potentially for T. deion, but not for T. pretiosum. T. deion may be the best candidate for augmentative biological control because it parasitized either slightly or significantly more eggs than the other two species in all four treatments. Furthermore, the pattern of parasitism by T. deion in the 36 four-egg patches treatment was the most aggregated among the three species, suggesting a more thorough searching pattern. In contrast, T. pretiosum had the least aggregated pattern of parasitism and therefore may have used a more random foraging pattern