The Sage-Grouse Habitat Mortgage: Effective Conifer Management in Space and Time

Management of conservation-reliant species can be complicated by the need to manage ecosystem processes that operate at extended temporal horizons. One such process is the role of fire in regulating abundance of expanding conifers that disrupt sage-grouse habitat in the northern Great Basin of the United States. Removing conifers by cutting has a beneficial effect on sage-grouse habitat. However, effects may last only a few decades because conifer seedlings are not controlled and the seed bank is fully stocked. Fire treatment may be preferred because conifer control lasts longer than for mechanical treatments. The amount of conservation needed to control conifers at large temporal and spatial scales can be quantified by multiplying land area by the time needed for conifer abundance to progress to critical thresholds (i.e., “conservation volume”). The contribution of different treatments in arresting conifer succession can be calculated by dividing conservation volume by the duration of treatment effect. We estimate that fire has approximately twice the treatment life of cutting at time horizons approaching 100 yr, but, has high up-front conservation costs due to temporary loss of sagebrush. Cutting has less up-front conservation costs because sagebrush is unaffected, but it is more expensive over longer management time horizons because of decreased durability. Managing conifers within sage-grouse habitat is difficult because of the necessity to maintain the majority of the landscape in sagebrush habitat and because the threshold for negative conifer effects occurs fairly early in the successional process. The time needed for recovery of sagebrush creates limits to fire use in managing sage-grouse habitat. Utilizing a combination of fire and cutting treatments is most financially and ecologically sustainable over long time horizons involved in managing conifer-prone sage-grouse habitat.     

The dynamics of the onset of frictional slip

The way in which a frictional interface fails is critical to our fundamental understanding of failure processes in fields ranging from engineering to the study of earthquakes. Frictional motion is initiated by rupture fronts that propagate within the thin interface that separates two sheared bodies. By measuring the shear and normal stresses along the interface, together with the subsequent rapid real-contact-area dynamics, we find that the ratio of shear stress to normal stress can locally far exceed the static-friction coefficient without precipitating slip. Moreover, different modes of rupture selected by the system correspond to distinct regimes of the local stress ratio. These results indicate the key role of nonuniformity to frictional stability and dynamics with implications for the prediction, selection, and arrest of different modes of earthquakes.     

Manufacturing molecules through metabolic engineering

Metabolic engineering has the potential to produce from simple, readily available, inexpensive starting materials a large number of chemicals that are currently derived from nonrenewable resources or limited natural resources. Microbial production of natural products has been achieved by transferring product-specific enzymes or entire metabolic pathways from rare or genetically intractable organisms to those that can be readily engineered, and production of unnatural specialty chemicals, bulk chemicals, and fuels has been enabled by combining enzymes or pathways from different hosts into a single microorganism and by engineering enzymes to have new function. Whereas existing production routes use well-known, safe, industrial microorganisms, future production schemes may include designer cells that are tailor-made for the desired chemical and production process. In any future, metabolic engineering will soon rival and potentially eclipse synthetic organic chemistry.     

Absence of Transgenerational Phenotypic Plasticity in Fecundity in the Parasitoid Anagrus erythroneurae (Hymenoptera: Mymaridae)

To improve biological pest control, we would like to understand the main factors that limit the reproductive success of key biological control agents, including parasitoid wasps. Previous research with proovigenic parasitoids in the genus Anagrus collected from multiple field sites revealed positive correlations between parasitoid fecundity and local host density. In this article, we test whether this variation in fecundity is a reflection of transgenerational phenotypic plasticity. We exposed females in laboratory microcosms to either low or high host densities and then quantified the fecundity of their adult daughters. Mean fecundity of daughters did not differ across host density treatments, arguing against the operation of phenotypic plasticity. Significant variation in mean fecundity across different families instead suggested the possibility that genetic variation may underlie the observed fecundity differences.     

Glutamate-activated chloride channels: Unique fipronil targets present in insects but not in mammals

Selectivity to insects over mammals is one of the important characteristics for a chemical to become a useful insecticide. Fipronil was found to block cockroach GABA receptors more potently than rat GABA_A receptors. Furthermore, glutamate-activated chloride channels (GluCls), which are present in cockroaches but not in mammals, were very sensitive to the blocking action of fipronil. The IC₅₀s of fipronil block were 30 nM in cockroach GABA receptors and 1600 nM in rat GABA_A receptors. Moreover, GluCls of cockroach neurons had low IC₅₀s for fipronil. Two types of glutamate-induced chloride current were observed: desensitizing and non-desensitizing, with fipronil IC₅₀s of 800 and 10 nM, respectively. We have developed methods to separately record these two types of GluCls. The non-desensitizing and desensitizing currents were selectively inhibited by trypsin and polyvinylpyrrolidone, respectively. In conclusion, in addition to GABA receptors, GluCls play a crucial role in selectivity of fipronil to insects over mammals. GluCls form the basis for development of selective and safe insecticides.     

Chemical control of the European tarnished plant bug, Lygus rugulipennis, on strawberry in the UK

European tarnished plant bug, Lygus rugulipennis, is a serious pest on late season strawberries in the UK. Feeding by the pest on the developing fruits causes severe malformation, and over 50% of fruit may be downgraded as a result of capsid feeding in unsprayed crops. A range of compounds was tested against the pest over two years at East Malling Research. In 2008 experiments were conducted on weed plots with high L. rugulipennis populations, and in 2009 were conducted on an everbearer strawberry planting. The 2008 experiments showed that etoxazole had no effect on L. rugulipennis and that although flonicamid and indoxacarb significantly reduced populations they were not as effective as thiacloprid, either with or without a surfactant, or acetamiprid. In the 2009 experiment on strawberry thiacloprid + surfactant, applied twice, was more effective than this treatment applied once, which in turn was more effective than thiacloprid alone. In both years the most effective treatment was the pyrethroid bifenthrin. There was no suggestion that different developmental stages of the pest were more susceptible to the tested insecticides. Thus there was no evidence to suggest that timing applications against specific life stages would significantly improve pest control.     

Evaluation of Two Products Recently Introduced as Nitrification Inhibitors

This study compared the relative effectiveness of two products recently introduced as nitrification inhibitors with other materials used to inhibit nitrification. Four soils were treated with 0, 0.2, 1, 5, and 25 mg kg^?1 of nitrapyrin (NP), a new microencapsulated nitrapyrin product (ENP), dicyandiamide (DCD), a new maleic-itaconic polymer product (MIP), and ammonium thiosulfate (ATS). The soils were also treated with 200 mg N kg^?1 as urea, and percent inhibition of nitrification determined after 2 or 4 weeks of incubation. After 4 weeks, similar levels of nitrification inhibition were provided by 1 mg kg^?1 of NP (72%), 5 mg kg^?1 of ENP (79%), and 25 mg kg^?1 of DCD (73%), averaged across soil. After 4 weeks with a sandy soil, the highest rate of MIP and ATS provided 15 and 36% inhibition, respectively. MIP and ATS were ineffective at inhibiting nitrification when added to the other three soils.

Abbreviations: ATS: ammonium thiosulfate; DCD: dicyandiamide; ENP: encapsulated nitrapyrin; MIP: maleic-itaconic polymer; NP: nitrapyrin; UAN: urea-ammonium nitrate liquid fertilizer     

Characterizing state-managed and unmanaged fisheries in coastal marine states and territories of the United States

The status of federally managed fisheries in the United States is well monitored, but the condition of other marine fisheries, whether state-managed, territory-managed or unmanaged, is less understood and often unknown. We used expert surveys to characterize the management systems of non-federally managed fisheries in US coastal marine states and overseas territories. For 311 fisheries, we estimated an overall Fisheries Management Index (FMI) and a qualitative stock status score. These measures were positively correlated, and while a wide range of research, management, enforcement and socioeconomic criteria were partially met (FMI ≥ 0.5) for 66% of fisheries, stock status was considered as partially acceptable (score ≥ 0.5) for only 45% of fisheries and acceptable (score = 1) for only 16% of fisheries. Higher FMI was typically observed in fisheries with greater commercial landed weight, value, or greater recreational catches. Fisheries from continental states had higher FMI than those from overseas territories. Invertebrates and diadromous fish species had higher FMI on average compared to those of marine fishes. Extrapolating results for surveyed fisheries to nearly 2000 non-federally managed US fisheries while stratifying by state and importance designation (based on commercial, recreational, cultural or ecological importance), we estimate a mean overall FMI of 0.48, and estimate that only 19% of fisheries have a reliable estimate of stock status available; both measures are lower than similar estimates for federally managed fisheries. Funding or capacity constraints and information or data limitations were identified as common challenges faced by state agencies in managing fisheries under their jurisdiction.     

Organic Fertilizer Source and Application Method Impact Ammonia Volatilization

ABSTRACT

Ammonia (NH₃) volatilization from fertilizer applications reduces efficiency and poses environmental hazards. This study used semi-open static chambers to measure NH₃ volatilization from organic fertilizers (feather meal, blood meal, fish emulsion, cyano-fertilizer) to evaluate the impacts of fertilizer source, application method, and rate on NH₃ volatilization. In 2014, two application rates (28 and 56 kg N ha^?1) were applied to lettuce (Lactuca sativa L.). Solid fertilizers (feather meal, blood meal) were preplant applied in a subsurface band, whereas liquid fertilizers (fish emulsion, cyano-fertilizer) were applied weekly through drip irrigation beginning two weeks after transplanting. In 2015, a single application rate (28 kg N ha^?1) was applied to cucumber (Cucumis sativus L.). Solid fertilizers were applied in either subsurface or surface bands. There was a significant difference in NH₃ volatilization among fertilizers, but there was little difference between application rates. Liquid fertilizers had lower NH₃ emissions than solid fertilizers due to their timing and placement. In 2014, blood meal at 56 kg N ha^?1 and feather meal at both rates had the highest NH₃ fluxes. In 2015, surface-banded blood and feather meal had the highest NH₃ fluxes. Fertilizer decisions for organic systems should consider NH₃ emission losses and practices for their reduction.     

Inhibition of aflatoxin biosynthesis in Aspergillus flavus by diferuloylputrescine and p-coumaroylferuloylputrescine

A mixture of diferuloylputrescine/p-coumaroylferuloylputrescine (85:15, w/w) demonstrated inhibitory activity against aflatoxin B1 biosynthesis in Aspergillus flavus isolate AF13. Inhibition was concentration dependent, with a 50% effective dose of 30 microg of diferuloylputrescine/p-coumaroylferuloylputrescine per milliliter of medium. Aflatoxin inhibition levels of up to 93% were achieved using this conjugated polyamine material. This diconjugated polyamine mixture did not display inhibitory effects on A. flavus growth (mycelial weight) at any of the concentrations tested. A survey of hand-dissected corn (Zea mays) kernel tissues, including endosperm, germ, pericarp, and wax, revealed that the highest concentrations of these conjugated polyamines were localized in the pericarp of the seed. Analysis of a number of corn accessions did not reveal a correlation between diferuloylputrescine/ p-coumaroylferuloylputrescine concentration and resistance/susceptibility to A. flavus infection. The localization of these diconjugated polyamine components in the pericarp, which functions as a physical barrier and surrounds the internal food storage reserves, suggests a defensive role for these materials.