Lethal Temperatures of Diapausing \u3ci\u3eBathyplectes Curculionis\u3c/i\u3e (Hymenoptera: Ichneumonidae) a Parasite of the Alfalfa Weevil (Coleoptera: Curculionidae)

Seasonally acclimatized diapausing larvae of Bathyplectes curculionis (Thomson) were exposed to extreme hxgh and low temperatu~es to determine lethal temperatures for this stage of the parasite. The possible effects of relative humidity on high temperature mortality, mortality induced by repetitive exposures to sublethal temperatures, and differential survival between sexes, were also measured. The upper lethal temperature for summer larvae was 60°C (LDSo from 2 to 4 h), and the lower lethal temperature for winter larvae was -25°C (LDSo from 0 to % h). Summer larvae showed significantly increased mortality with repetitive exposures to sublethal temperatures (55OC) whereas winter larval mortality did not increase significantly with repetitive exposures to sublethal temperatures (-20°C). In winter experiments in which the sex of the emerging adult could be measured, no significant difference in survival was found between the sexes. Our results, in conjunction with published field data, strongly suggest that heat kill in the summer may be a significant mortality factor in warmer areas of the parasite\u27s range

Influences of Host Density, Temperature, and Parasite Age on the Reproductive Potential of \u3ci\u3eBathyplectes Curculionis\u3c/i\u3e (Hymenoptera: Ichneumonidae), an Endoparasite of the Alfalfa Weevil (Coleoptera: Curculionidae)

Alfalfa weevil larvae were exposed to Bathyplectes curculionis (Thomson) to determine the effect of host density, temperature, and parasite age on the reproductive potential of curculionis. Percent parasitism was found to be inversely proportional to host density and most of the parasites distributed their eggs randomly regardless of host density. The number of eggs deposited was largely independent of temperature. Peak egg laying was reached in three days from which point the parasite\u27s capabilities diminished with increasing age. The longevity of ovipositing females was shorter than females that were not exposed to larvae

Population genetics of the Manila clam (Ruditapes philippinarum) introduced in North America and Europe

Versión del edito

A model of black cutworm (Agrotis ipsilon) development : a description, uses, and implications

Bibliography: p. 21-22

Plateau voor vleesvarkens

De varkenshouderij in Nederland heeft te maken met het Varkensbesluit 1998, waarin een aantal welzijnsnormen zijn opgenomen. Een van de normen is dat de minimum beschikbare vloeroppervlakte per varken (85-110 kg) is vergroot van 0,7 m2 tot 1,0 m2 ten opzichte van het Varkensbesluit 199

Expected Limits on the Ocean Acidification Buffering Potential of a Temperate Seagrass Meadow

Ocean acidification threatens many marine organisms, especially marine calcifiers. The only global‐scale solution to ocean acidification remains rapid reduction in CO2 emissions. Nevertheless, interest in localized mitigation strategies has grown rapidly because of the recognized threat ocean acidification imposes on natural communities, including ones important to humans. Protection of seagrass meadows has been considered as a possible approach for localized mitigation of ocean acidification due to their large standing stocks of organic carbon and high productivity. Yet much work remains to constrain the magnitudes and timescales of potential buffering effects from seagrasses. We developed a biogeochemical box model to better understand the potential for a temperate seagrass meadow to locally mitigate the effects of ocean acidification. Then we parameterized the model using data from Tomales Bay, an inlet on the coast of California, USA which supports a major oyster farming industry. We conducted a series of month‐long model simulations to characterize processes that occur during summer and winter. We found that average pH in the seagrass meadows was typically within 0.04 units of the pH of the primary source waters into the meadow, although we did find occasional periods (hours) when seagrass metabolism may modify the pH by up to ±0.2 units. Tidal phasing relative to the diel cycle modulates localized pH buffering within the seagrass meadow such that maximum buffering occurs during periods of the year with midday low tides. Our model results suggest that seagrass metabolism in Tomales Bay would not provide long‐term ocean acidification mitigation. However, we emphasize that our model results may not hold in meadows where assumptions about depth‐averaged net production and seawater residence time within the seagrass meadow differ from our model assumptions. Our modeling approach provides a framework that is easily adaptable to other seagrass meadows in order to evaluate the extent of their individual buffering capacities. Regardless of their ability to buffer ocean acidification, seagrass meadows maintain many critically important ecosystem goods and services that will be increasingly important as humans increasingly affect coastal ecosystems

Generalized nonreciprocity in an optomechanical circuit via synthetic magnetism and reservoir engineering

Synthetic magnetism has been used to control charge neutral excitations for applications ranging from classical beam steering to quantum simulation. In optomechanics, radiation-pressure-induced parametric coupling between optical (photon) and mechanical (phonon) excitations may be used to break time-reversal symmetry, providing the prerequisite for synthetic magnetism. Here we design and fabricate a silicon optomechanical circuit with both optical and mechanical connectivity between two optomechanical cavities. Driving the two cavities with phase-correlated laser light results in a synthetic magnetic flux, which in combination with dissipative coupling to the mechanical bath, leads to nonreciprocal transport of photons with 35dB of isolation. Additionally, optical pumping with blue-detuned light manifests as a particle non-conserving interaction between photons and phonons, resulting in directional optical amplification of 12dB in the isolator through direction. These results indicate the feasibility of utilizing optomechanical circuits to create a more general class of nonreciprocal optical devices, and further, to enable novel topological phases for both light and sound on a microchip.Comment: 18 pages, 8 figures, 4 appendice

Comparison of shallow-water seston among biogenic habitats on tidal flats

Aquatic structure-formers have the potential to establish mosaics of seston in shallow water if they modify the relative amounts of deposition (or filtration) and resuspension of particles. By sampling surface water adjacent to Lagrangian drifters traveling 0.1 to 2 m above the bottom, we tested the modification of seston in water masses flowing over two biogenic marine species (native eelgrass, Zostera marina; introduced oysters, Crassostrea gigas) in comparison to unstructured tidal flats. Water properties were examined at five intertidal sites in Washington State, USA, each with 27 drifts (three drifts at different stages of the tidal cycle in each of three patches of three habitat types; drift distance 116 m (109SD), duration 24 min (15SD)). At the initiation of each drift, habitat differences in water properties were already apparent: chlorophyll-a and total suspended solid (TSS) concentrations were greater in structured habitats than bare, and TSS was also inversely related to water depth. Water flowed more slowly across eelgrass than other habitat types. As water flowed across each habitat type, TSS generally increased, especially in shallow water, but without habitat differences; chlorophyll-a in these surface-water samples showed no consistent change during drifts. At higher TSS concentrations, quality in terms of organic content declined, and this relationship was not habitat-specific. However, quality in terms of chlorophyll-a concentration increased with TSS, as well as being greater in water over eelgrass than over other habitat types. These results support widespread mobilization of seston in shallow water ebbing or flooding across Washington State’s tidal flats, especially as water passes into patches of biogenic species

Ecological Invasion, Roughened Fronts, and a Competitor's Extreme Advance: Integrating Stochastic Spatial-Growth Models

Both community ecology and conservation biology seek further understanding of factors governing the advance of an invasive species. We model biological invasion as an individual-based, stochastic process on a two-dimensional landscape. An ecologically superior invader and a resident species compete for space preemptively. Our general model includes the basic contact process and a variant of the Eden model as special cases. We employ the concept of a "roughened" front to quantify effects of discreteness and stochasticity on invasion; we emphasize the probability distribution of the front-runner's relative position. That is, we analyze the location of the most advanced invader as the extreme deviation about the front's mean position. We find that a class of models with different assumptions about neighborhood interactions exhibit universal characteristics. That is, key features of the invasion dynamics span a class of models, independently of locally detailed demographic rules. Our results integrate theories of invasive spatial growth and generate novel hypotheses linking habitat or landscape size (length of the invading front) to invasion velocity, and to the relative position of the most advanced invader.Comment: The original publication is available at www.springerlink.com/content/8528v8563r7u2742