Straw Itch Mite, \u3ci\u3ePyemotes Tritici\u3c/i\u3e, Infestation in Brome Seed Related to Acute Dermatitis in Michigan Granary Workers

An infestation of Pyemotes tritici, the straw itch mite, apparently caused dermatitis on the arms and trunks of four workers in south-central Michigan who had unloaded a shipment of brome seed bags. Sampling of bag surfaces and contents indicated that mites occurred inside and on the surface of brome seed bags, but not in bags of other seed present at the site. One bag of fescue in contact with brome seed bags had mites on its surface. Pyemotes tritici densities on the brome seed bags ranged from 0.7 -5.6 per cm , while infestations in brome seed ranged from 0.08-0.33 mites per ml of seed. An insect repellent containing DEET was effective in preventing mite bites

Establishment, Impacts, and Current Range of Spotted Knapweed (\u3ci\u3eCentaurea Stoebe\u3c/i\u3e Ssp. \u3ci\u3eMicranthos\u3c/i\u3e) Biological Control Insects in Michigan

Centaurea stoebe L. ssp. micranthos (Gugler) Hayek (spotted knapweed) is an invasive plant that has been the target of classical biological control in North America for more than four decades. Work in the western U.S. and Canada has shown the seedhead-feeding weevils Larinus minutus Gyllenhal and Larinus obtusus Gyllenhal (Coleoptera: Curculionidae) and the root-boring weevil Cyphocleonus achates (Fahraeus) (Coleoptera: Curculionidae) to be the most effective C. stoebe control agents. These three weevils have recently been introduced into the eastern U.S., including sites in Michigan in 2007 and 2009. In 2010, we made additional releases at six sites in Michigan, monitoring them for three years 2011-13. Here we report on the establishment, impact, and cur- rent range of L. minutus, L. obtusus, and C. achates in Michigan. We also report on the initial results of native plant overseeding treatments that were applied to biological control release sites with the aim of supplementing the nectar source C. stoebe provides. We found that L. minutus has established at all of its Michigan release sites and is widespread in the southwestern part of the state, while L. obtusus has established at the single site where it was released in 2007 and is spreading to adjoining counties. We also found C. achates to be present at four sites and established at one additional site in Michigan, but in all cases abundances are low and dispersal has been minimal (\u3c 10 m). In the three years following the 2010 releases, we found no measurable impacts of these biological control agents on C. stoebe growth, demographics, or plant community metrics. We also found little evidence of native flowering plant establishment at seeded sites. These baseline data will be useful in monitoring the spread and potential impacts of biological control agents on C. stoebe in Michigan

Herbaceous Filter Strips in Agroecosystems: Implications for Ground Beetle (Coleoptera: Carabidae) Conservation and Invertebrate Weed Seed Predation

A 9.3-ha crop field flanked by two filter strips was selected to: 1) assess carabid beetle activity-density and community composition and 2) assess post-dispersal weed seed predation by invertebrates in these habitats. Over- all during 1997 and 1998, 12,937 carabid beetles comprising 58 species were collected. Greater species richness and activity-density was observed in filter strips than in the field. A multivariate ordination revealed that year of capture and habitat were important variables conditioning carabid beetle com­munities. While two omnivorous species known to eat weed seeds [Harpalus erraticus (Say), Anisodactylus sanctaecrucis (F.)] dominated the 1997 captures, two carnivorous [Pterostichus melanarius (Ill), Pterostichus permundus (Say)] were predominant in 1998. Two omnivorous species, Harpalus pensylvanicus (DeG) and H. erraticus, were primarily captured in filter strips. Weed seed removal was greater in filter strips than in the field. This study shows that habitat management represents a feasible approach to con­serve beneficial organisms in farmlands

Detection of Prolonged Diapause of Northern Corn Rootworm in Michigan (Coleoptera: Chrysomelidae)

Prolonged diapause of northern corn rootworm, while known from other Midwestern states, has not previously been reported in Michigan. Populations of northern corn rootworm, (Diabrotica barberi) from two first-year corn fields in Genesee County, Michigan were examined for prolonged egg diapause. Pro- longed diapause was suspected in these populations due to an unusually high proportion of northern versus western corn rootworms in these fields. Eggs obtained from females collected at these sites were reared in the laboratory for two years. The presence of the prolonged diapause trait was confirmed in one population by eggs which hatched following two simulated winters (7.3%). None of the eggs m the second population hatched following the second chill period, however, some eggs in this population remained in apparent diapause at the end of two years. The potential for using observed population shifts in favor of D. barberi as an early warning of the expansion of prolonged diapause in a population is discussed

Ecological Observations on Predatory Coccinellidae (Coleoptera) in Southwestern Michigan

Ecological observations on habitat utilization by thirteen species of predatory Coccinellidae were made at a southern Michigan site during 1989 and 1990. Most of species were common during both years and used both agricul- tural and uncultivated habitats. Coccinella septempunctata and Coleomegilla maculata, were the most abundant in agricultural crops (alfalfa, maize, soy- bean and triticale), whereas Adalia bipunctata and Cycloneda munda, were the most abundant in deciduous and bushy habitats

The GaAs solar cells with V-grooved emitters

Geometrically structured surfaces have become increasingly important to solar cell efficiency improvements and radiation tolerance. Gallium arsenide solar cells with a V-grooved front surface which demonstrate improved optical coupling and higher short-circuit current compared to planar cells were fabricated. GaAs homojunction cells were fabricated by organometallic chemical vapor deposition (OMCVD) on an n+ substrate. The V-grooves were formed on the surface with an anisotropic etch, and an n-type buffer and p-type emitter were grown by OMCVD, followed by ohmic contacts. Reflectivity measurements show significantly lower reflectance for the microgrooved cell compared to the planar structure. The short circuit current of the V-grooved solar cell is consistently higher than that of the planar controls

A V-grooved GaAs solar cell

V-grooved GaAs solar cells promise the benefits of improved optical coupling, higher short-circuit current, and increased tolerance to particle radiation compared to planar cells. A GaAs homojunction cell was fabricated by etching a V-groove pattern into an n epilayer (2.1 x 10 to the 17th power per cu cm) grown by metalorganic chemical vapor deposition (MOCVD) on an n+ substrate (2.8 x 10 to the 18th power per cu cm) and then depositing and MOCVD p epilayer (4.2 x 10 to the 18th power per cu cm). Reflectivity measurements on cells with and without an antireflective coating confirm the expected decrease in reluctance of the microgrooved cell compared to the planar structure. The short circuit current of the V-grooved solar cell was 13 percent higher than that of the planar control

Contact-Induced Emigration of Potato Leafhopper (Homoptera: Cicadellidae) from Alfalfa-Forage Grass Mixtures

Studies were conducted to evaluate the mechanisms leading to increased potato leafhopper, Empoasca fabae (Harris), emigration from alfalfa-forage grass mixtures. A laboratory behavioral bioassay was used to measure daily emigration rates of adult leafhoppers from alfalfa, Medicago sativa L.; smooth bromegrass, Bromus inermis Leyss.; orchardgrass, Dactylis glomerata L.; and timothy, Phleum pratense L., alone and in 1:1 mixtures of each grass with alfalfa. Emigration was ≍9-fold greater from pure bromegrass and orchardgrass treatments versus alfalfa alone, and ≍5-fold greater than from mixtures of alfalfa and each grass species. In a 2nd experiment, alfalfa and forage grasses were separated by a barrier permeable to plant volatiles. Only 31% of the potato leafhoppers placed on alfalfa adjacent to either alfalfa or grass emigrated. However, when introduced to the side containing a forage grass, <85% of the leafhoppers emigrated, regardless of adjacent plant. Thus, stimuli obtained from physical contact with the grass versus grass volatiles alone were required to elicit emigration. Observations of potato leafhoppers on single plants of smooth bromegrass, orchardgrass, and alfalfa revealed that individuals fed on all 3 species; however, the frequency and duration of probing differed as did mean residency time (10.7 h alfalfa, 7.5 h bromegrass, 5.9 h orchardgrass). These experiments suggested that physical contact is necessary to elicit emigration from grasses. By increasing emigration, alfalfa-forage grass mixtures may reduce potato leafhopper damage to alfalfa. Additionally, intercropping with forage grasses may lower the number of feeding bouts on alfalfa and reduce subsequent hopperbur

Testing of the on-board attitude determination and control algorithms for SAMPEX

Algorithms for on-board attitude determination and control of the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) have been expanded to include a constant gain Kalman filter for the spacecraft angular momentum, pulse width modulation for the reaction wheel command, an algorithm to avoid pointing the Heavy Ion Large Telescope (HILT) instrument boresight along the spacecraft velocity vector, and the addition of digital sun sensor (DSS) failure detection logic. These improved algorithms were tested in a closed-loop environment for three orbit geometries, one with the sun perpendicular to the orbit plane, and two with the sun near the orbit plane - at Autumnal Equinox and at Winter Solstice. The closed-loop simulator was enhanced and used as a truth model for the control systems' performance evaluation and sensor/actuator contingency analysis. The simulations were performed on a VAX 8830 using a prototype version of the on-board software

Peeled film GaAs solar cells for space power

Gallium arsenide (GaAs) peeled film solar cells were fabricated, by Organo-Metallic Vapor Phase Epitaxy (OMVPE), incorporating an aluminum arsenide (AlAs) parting layer between the device structure and the GaAs substrate. This layer was selectively removed by etching in dilute hydrofloric (HF) acid to release the epitaxial film. Test devices exhibit high series resistance due to insufficient back contact area. A new design is presented which uses a coverglass superstrate for structural support and incorporates a coplanar back contact design. Devices based on this design should have a specific power approaching 700 W/Kg