Predators associated with hemlock woolly adelgid (Hemiptera: Adelgidae) infested western hemlock in the Pacific Northwest.

The hemlock woolly adelgid, Adelges tsugae, is causing widespread mortality of eastern hemlock, Tsuga canadensis, in the eastern United States. In the West, A. tsugae causes negligible damage to western hemlock, Tsuga heterophylla. Host tolerance traits and presence of endemic predators may be contributing to the relative tolerance of western hemlock to A. tsugae. Field surveys of the predator community associated with A. tsugae infestations on 116 T. heterophylla at 16 locations in Oregon and Washington were conducted every four to six weeks from March 2005 through November 2006. Predators collected from A. tsugae infested T. heterophylla represent 55 species in 14 families, listed in order of abundance: Derodontidae, Chamaemyiidae, Hemerobiidae, Coccinellidae, Cantharidae, Reduviidae, Miridae, Syrphidae, Chrysopidae, Coniopterygidae, Staphylinidae, Anthocoridae, Nabidae, and Raphidiidae. Laricobius nigrinus (Derodontidae), Leucopis argenticollis, and Leucopis atrifacies (Chamaemyiidae) are the most abundant predators; together comprising 59% of predator specimens recovered. The abundance of derodontid larvae, L. nigrinus adults, chamaemyiid larvae, and L. argenticollis adults was found to be positively correlated to A. tsugae density. The remaining 52 species represent a diverse complex of predators potentially attacking A. tsugae. However, many are known to feed on non-adelgid prey. Predators were most abundant when the two generations of A. tsugae eggs were present. The phenology of immature and adult predators suggests temporal partitioning of prey across all seasons. Fifteen predator species were either reared from larvae to adult on a diet of A. tsugae in the laboratory or were observed feeding on A. tsugae. L. argenticollis and L. atrifacies were reared on A. tsugae in the laboratory and host records show them to feed exclusively on Adelgidae. Both species should be investigated as candidates for A. tsugae biological control in eastern North America

Secularization, Union Formation Practices, and Marital Stability: Evidence from Italy

Descriptive statistics indicate that civil marriages and marriages preceded by premarital cohabitation are more unstable, i.e., more frequently followed by divorce. However, the literature has shown that selectivity plays an important role in the relationship between premarital cohabitation and union dissolution. We do not have evidence to date regarding the selectivity in the effect of civil marriage. The Italian case appears particularly interesting given the recent diffusion of premarital cohabitation and civil marriage. Using micro-level data from a national-level representative survey conducted in 2003, we develop a multiprocess model that allows unobserved heterogeneity to be correlated across the three decisions (premarital cohabitation, civil marriage, and divorce). Our results show that selectivity is the main factor that explains the higher divorce rates among those who experience premarital cohabitation and a civil marriage. Net of selectivity, the causal effect on union dissolution disappears

Nothing Lasts Forever: Environmental Discourses on the Collapse of Past Societies

The study of the collapse of past societies raises many questions for the theory and practice of archaeology. Interest in collapse extends as well into the natural sciences and environmental and sustainability policy. Despite a range of approaches to collapse, the predominant paradigm is environmental collapse, which I argue obscures recognition of the dynamic role of social processes that lie at the heart of human communities. These environmental discourses, together with confusion over terminology and the concepts of collapse, have created widespread aporia about collapse and resulted in the creation of mixed messages about complex historical and social processes

High-Frequency Dimensional Effects in Ferrite-Core Magnetic Devices

MnZn ferrites are widely used in power electronics applications where the switching frequency is in the range of several tens of kilohertz to a megahertz. In this range of frequencies the combination of relatively high permeability and relatively low conductivity found in MnZn ferrite helps to minimize the size of magnetic devices while maintaining high efficiency. The continuing improvement in semiconductor switches and circuit topologies has led to use of high-frequency switching circuits at ever increasing power levels. The magnetic devices for these high-power, high-frequency circuits require magnetic CORES that are significantly larger than standard ferrite-core devices used at lower power levels. Often such large ferrite cores must be custom designed, and at present this custom design is based on available material information without regard for the physical size of the structure. This thesis examines..

Ips paraconfususLanier (Coleoptera: Curculionidae): New Records of the California Fivespined Ips from Washington State and the Columbia River Gorge in Oregon

Murray, Todd A., Kohler, Glenn R., Willhite, Elizabeth A. (2013): Ips paraconfususLanier (Coleoptera: Curculionidae): New Records of the California Fivespined Ips from Washington State and the Columbia River Gorge in Oregon. The Coleopterists Bulletin 67 (1): 27-31, DOI: 10.1649/072.067.0106, URL: http://dx.doi.org/10.1649/072.067.010