Trap placement and attractant choice affect capture and create sex and parity biases in collections of the biting midge,Culicoides sonorensis

Culicoides sonorensis Wirth & Jones (Diptera: Ceratopogonidae) is the primary North American vector of bluetongue virus (BTV), which can cause high morbidity and mortality in ruminant livestock or wildlife. Worldwide, most Culicoides surveillance relies on light (usually UV) traps typically placed near animals or larval development sites. However, the trapping method can cause sex, species and parity biases in collections. We collected C. sonorensis from three dairies in California using suction traps baited with CO₂, UV light or CO₂ + UV placed near animals, wastewater ponds, or in fields. Higher numbers of parous females were collected using CO₂ + UV traps, although this difference was only significant on one dairy. UV traps were poor at collecting nulliparous females, but the addition of UV to a trap increased the abundance of males in a collection. Traps set in open fields collected significantly higher numbers of males and females than in either of the other two locations. In some cases, there was a significant interaction between the trap type and site. We discuss the limitations of traditional trapping methodologies for C. sonorensis and make suggestions for vector surveillance.     

Food, Feeding Behavior and Feeding Ecology of Nemerteans

The feeding biology of nemerteans is reviewed, new informationis presented, and the role of nemerteans in natural communitiesis discussed and evaluated. Most nemerteans are carnivorous,the majority feeding on live, often specific, prey, while someare scavengers. Macrophagous feeding is found in the Palaeonemertea,Heteronemertea and some of the Hoplonemertea; the more specializedsuctorial feeding is limited to five of the hoplonemertean families,and suspension feeding (omnivorous diet) occurs only in thehighly specialized symbiotic monogeneric Bdellonemertea. Feeding adaptations seem to be related to the nature and employmentof the proboscis, the dilatability of the mouth, and the structureof the anterior part of the digestive tract. The transport ofdissolved organic materials from seawater has been demonstrated,but its role in nemertean nutrition is just being contemplated.Present meager information on predation has shown nemerteansto have actually and potentially large effects on prey populationsand thus on the communities in which they live. As the feedingbiology of only a relative handful of species has been studied,much basic comparative research is needed before we can corroborateor refute our present ideas concerning the ecological rolesof nemerteans.     

A geothermal‐linked biological oasis in Yellowstone Lake,Yellowstone National Park,Wyoming

Hundreds of active and dormant geothermal vents have been located on the floor of Yellowstone Lake, although characterization of the associated biology (macro or micro) has been extremely limited. Herein, we describe an aquatic moss (Fontinalis) colony closely associated with vent emissions that considerably exceeded known temperature maxima for this plant. Vent waters were supersaturated with CO₂, likely accommodating a CO₂ compensation point that would be expected to be quite elevated under these conditions. The moss was colonized by metazoa, including the crustaceans Hyalella and Gammarus, a segmented worm in the Lumbriculidae family, and a flatworm specimen tentatively identified as Polycelis. The presence of these invertebrates suggest a highly localized food chain that derives from the presence of geothermal inputs and thus is analogous to the deep marine vents that support significant biodiversity.     

Chemical reactivity of microbe and mineral surfaces in hydrous ferric oxide depositing hydrothermal springs

The hot springs in Yellowstone National Park, USA, provide concentrated microbial biomass and associated mineral crusts from which surface functional group (FG) concentrations and pK_a distributions can be determined. To evaluate the importance of substratum surface reactivity for solute adsorption in a natural setting, samples of iron‐rich sediment were collected from three different springs; two of the springs were acid‐sulfate‐chloride (ASC) in composition, while the third was neutral‐chloride (NC). At one of the ASC springs, mats of S^º‐rich Hydrogenobaculum‐like streamers and green Cyanidia algae were also collected for comparison to the sediment. All samples were then titrated over a pH range of 3–11, and comparisons were made between the overall FG availability and the concentration of solutes bound to the samples under natural conditions. Sediments from ASC springs were composed of hydrous ferric oxides (HFO) that displayed surface FGs typical of synthetic HFO, while sediments from the NC spring were characterized by a lower functional group density, reflected by decreased excess charge over the titration range (i.e., lower surface reactivity). The latter also showed a lower apparent point of zero charge (PZC), likely due the presence of silica (up to 78 wt. %) in association with HFO. Variations in the overall HFO surface charge are manifest in the quantities and types of solutes complexed; the NC sediments bound more cations, while the ASC sediments retained significantly more arsenic, presumably in the form of arsenate (H₂AsO₄^?). When the microbial biomass samples were analyzed, FG concentrations summed over the titratable range were found to be an order of magnitude lower for the Sº‐rich mats, relative to the algal and HFO samples that displayed similar FG concentrations on a dry weight basis. A diffuse‐layer surface complexation model was employed to further illustrate the importance of surface chemical parameters on adsorption reactions in complex natural systems.     

Partial Reversion by 5-Aminouracil of the Inhibition of Coleoptile Growth in Hordeum vulgare by Large Volumes of Water

Barley seedlings show a differential response to an increasein the volume of water on which they are grown. On 20 ml, ascompared with 9 ml of water, germination of some seeds is delayedand growth of some coleoptiles is inhibited at 45 h. Both effectsincrease progressively from 9 to 20 ml. Treatment with 5-aminouracilcan reverse, in part, the effects of high volumes of water.With 12, 17, and 20 ml of solution 5-AU increases the frequencyof germination and coleoptile growth. Its effect is most markedon 20 ml of solution, i.e. the volume that produces the greatestover-all inhibition of growth when seeds are on water is theone at which 5-AU is most effective in stimulating growth. Ofthe three concentrations tested, 10^–4 M was most effectivewhen used at a volume of 20 ml.