Effect of cohabitation with white-faced ewes on estrous activity of Hampshire and Suffolk ewes exposed to rams in June

Two groups of 24 Hampshire and 26 Suffolk purebred ewes each were used to study effects of cohabitation with cyclic white-faced (WF) ewes on estrous activity in June. Ewes lambed in January, February and March and had been isolated from mature rams since the previous fall breeding. From June 1 to July 2, treated (T) ewes were exposed to vasectomized rams and to 65 WF ewes; control (C) ewes were exposed only to vasectomized rams. Ovulation was assessed with biweekly serum progesterone assays; crayon marks were used to detect estrus. Daily observations of ram behavior were conducted to assess sexual activity of rams joined with T and C ewes. Cohabitation with WF ewes increased (P less than .01) ovulation percentages from 46% in C (42% for Hampshires and 50% for Suffolks) to 76% in T ewes (79% for Hampshires and 73% for Suffolks). Mating percentage also was increased (P less than .05) by cohabitation with WF ewes from 14% for C ewes to 30% for T ewes. Rams with T + WF ewes spent more (P less than .05) time checking ewes for estrus than did rams with C ewes. Hence, cohabitation with cycling WF ewes increased ovulation and mating percentages. Many acyclic T ewes first ovulated after 10 or more days of teasing, possibly due to increased ram contact in the presence of WF ewes.     

Comparing sampling needs for variograms of soil properties computed by the method of moments and residual maximum likelihood

It has been generally accepted that the method of moments (MoM) variogram, which has been widely applied in soil science, requires about 100 sites at an appropriate interval apart to describe the variation adequately. This sample size is often larger than can be afforded for soil surveys of agricultural fields or contaminated sites. Furthermore, it might be a much larger sample size than is needed where the scale of variation is large. A possible alternative in such situations is the residual maximum likelihood (REML) variogram because fewer data appear to be required. The REML method is parametric and is considered reliable where there is trend in the data because it is based on generalized increments that filter trend out and only the covariance parameters are estimated. Previous research has suggested that fewer data are needed to compute a reliable variogram using a maximum likelihood approach such as REML, however, the results can vary according to the nature of the spatial variation. There remain issues to examine: how many fewer data can be used, how should the sampling sites be distributed over the site of interest, and how do different degrees of spatial variation affect the data requirements? The soil of four field sites of different size, physiography, parent material and soil type was sampled intensively, and MoM and REML variograms were calculated for clay content. The data were then sub-sampled to give different sample sizes and distributions of sites and the variograms were computed again. The model parameters for the sets of variograms for each site were used for cross-validation. Predictions based on REML variograms were generally more accurate than those from MoM variograms with fewer than 100 sampling sites. A sample size of around 50 sites at an appropriate distance apart, possibly determined from variograms of ancillary data, appears adequate to compute REML variograms for kriging soil properties for precision agriculture and contaminated sites.     

The analysis of ranked observations of soil structure using indicator geostatistics

Structure is an important physical feature of the soil that is associated with water movement, the soil atmosphere, microorganism activity and nutrient uptake. A soil without any obvious organisation of its components is known as apedal and this state can have marked effects on several soil processes. Accurate maps of topsoil and subsoil structure are desirable for a wide range of models that aim to predict erosion, solute transport, or flow of water through the soil. Also such maps would be useful to precision farmers when deciding how to apply nutrients and pesticides in a site-specific way, and to target subsoiling and soil structure stabilization procedures.

Typically, soil structure is inferred from bulk density or penetrometer resistance measurements and more recently from soil resistivity and conductivity surveys. To measure the former is both time-consuming and costly, whereas observations made by the latter methods can be made automatically and swiftly using a vehicle-mounted penetrometer or resistivity and conductivity sensors. The results of each of these methods, however, are affected by other soil properties, in particular moisture content at the time of sampling, texture, and the presence of stones. Traditional methods of observing soil structure identify the type of ped and its degree of development. Methods of ranking such observations from good to poor for different soil textures have been developed. Indicator variograms can be computed for each category or rank of structure and these can be summed to give the sum of indicator variograms (SIV).

Observations of the topsoil and subsoil structure were made at four field sites where the soil had developed on different parent materials. The observations were ranked by four methods and indicator and the sum of indicator variograms were computed and modelled for each method of ranking. The individual indicators were then kriged with the parameters of the appropriate indicator variogram model to map the probability of encountering soil with the structure represented by that indicator. The model parameters of the SIVs for each ranking system were used with the data to krige the soil structure classes, and the results are compared with those for the individual indicators. The relations between maps of soil structure and selected wavebands from aerial photographs are examined as basis for planning surveys of soil structure.     

Swift fox reintroductions on the Blackfeet Indian Reservation, Montana, USA

Swift foxes (Vulpes velox) were once common prairie inhabitants throughout western North America and were integral components within ecosystems and some Native American tribal cultures. In response to extirpation from tribal lands, the Blackfeet Tribe and Defenders of Wildlife reintroduced 123 captive-raised swift foxes from 1998 to 2002 to the Blackfeet Indian Reservation, Montana, USA. We used two success criteria, a population growth rate ?1.0 and an index count ?100 foxes, to determine if the reintroduction was a short-term success.We radiocollared and monitored swift foxes from 2003 to 2005 to estimate survival and fecundity. The swift fox population grew at a rate of 16% during 2003/2004 and 14% in 2004/2005. In addition, field crews observed 93 foxes in the summer of 2005.The swift fox population reached one, and very nearly both, of our short-term success criteria. In light of swift fox sign in areas where we were unable to observe foxes despite being aware of their presence, we believe there were ?100 foxes present in 2005. Based on our success criteria and the discovery of swift foxes 110 km from the release site, we consider this reintroduction a short-term success with promise for long-term success. The Blackfeet Tribe and Defenders of Wildlife have attained their goal of restoring a culturally important species to Tribal lands and have initiated a comeback of swift foxes beyond the Reservation border to the Rocky Mountain Front in Montana. Collaborative projects between tribes and non-governmental groups can play a vital role in our effort to conserve biologically and culturally significant species.     

The utility of transient sensitivity for wildlife management and conservation: Bison as a case study

Developing effective management strategies is essential to conservation biology. Population models and sensitivity analyses on model parameters have provided a means to quantitatively compare different management strategies, allowing managers to objectively assess the resulting impacts. Inference from traditional sensitivity analyses (i.e., eigenvalue sensitivity methods) is only valid for a population at its stable age distribution, while more recent methods have relaxed this assumption and instead focused on transient population dynamics. However, very few case studies, especially in long-lived vertebrates where transient dynamics are potentially most relevant, have applied these transient sensitivity methods and compared them to eigenvalue sensitivity methods. We use bison (Bison bison) at Badlands National Park as a case study to demonstrate the benefits of transient methods in a practical management scenario involving culling strategies. Using an age and stage-structured population model that incorporates culling decisions, we find that culling strategies over short time-scales (e.g., 1–5 years) are driven largely by the standing population distribution. However, over longer time-scales (e.g., 25 years), culling strategies are governed by reproductive output. In addition, after 25 years, the strategies predicted by transient methods qualitatively coincide with those predicted by traditional eigenvalue sensitivity. Thus, transient sensitivity analyses provide managers with information over multiple time-scales in contrast to the long time-scales associated with eigenvalue sensitivity analyses. This flexibility is ideal for adaptive management schemes and allows managers to balance short-term goals with long-term viability.     

Discovery and characterization of sulfoxaflor, a novel insecticide targeting sap-feeding pests

The discovery of sulfoxaflor [N-[methyloxido[1-[6-(trifluoromethyl)-3-pyridinyl]ethyl]-λ(4)-sulfanylidene] cyanamide] resulted from an investigation of the sulfoximine functional group as a novel bioactive scaffold for insecticidal activity and a subsequent extensive structure-activity relationship study. Sulfoxaflor, the first product from this new class (the sulfoximines) of insect control agents, exhibits broad-spectrum efficacy against many sap-feeding insect pests, including aphids, whiteflies, hoppers, and Lygus, with levels of activity that are comparable to those of other classes of insecticides targeting sap-feeding insects, including the neonicotinoids. However, no cross-resistance has been observed between sulfoxaflor and neonicotinoids such as imidacloprid, apparently the result of differences in susceptibility to oxidative metabolism. Available data are consistent with sulfoxaflor acting via the insect nicotinic receptor in a complex manner. These observations reflect the unique structure of the sulfoximines compared with neonicotinoids.     

Sorption of Polymeric Quaternary Ammonium Compounds to Humic Acid

Polymeric quaternary ammonium salts or polyquaterniums are used not only in the water and wastewater industry but also in cosmetics. The former have been extensively studied with sorption to wastewater treatment plant (WWTP) biosolids an important factor in their fate, mitigating release to the environment. Compounds of cosmetic origin have not received the same scrutiny as those used in other applications despite differences in their structure, characteristics and properties such as toxicity. In this work, the sorption of selected polyquaterniums found in cosmetics to treated humic acid, employed as a surrogate for WWTP biosolids, is investigated. For comparison, the sorption of poly(diallyldimethylammonium chloride) (poly(DADMAC)), a polyquaternium commonly used as a flocculant, and cetyl pyridinium chloride, a monomeric quaternary ammonium compound, are also determined. The humic acid/water partition coefficients (K _D) of cetyl pyridinium chloride (52,000?L?kg^?1) and poly(DADMAC) (2,200?L?kg^?1) were greater than those of the polyquaterniums found in cosmetics (200 to 1,200?L?kg^?1). Assumptions of partitioning mainly to biosolids and substantial removal relative to the influent concentration of WWTPs may therefore not be valid.     

Estimating Aboveground Net Primary Production in Grasslands: A Comparison of Nondestructive Methods

Aboveground net primary production (ANPP) is an important ecosystem property that is affected by environmental variability. ANPP in grasslands is typically measured by clipping peak live plant material. However, this method is time intensive (and therefore expensive), making it difficult to capture spatial and temporal variability. Additionally, it is impractical to use a destructive method to estimate ANPP in long-term, permanent plots. Thus, many double-sampling techniques have been developed to reduce costs and increase sample size. The objective of our study was to assess the accuracy and precision of nondestructive techniques to estimate ANPP as supplements to the traditional method of peak biomass harvest at two grassland sites. We harvested biomass and compared estimates from the same plots to 1) canopy interception using a point frame, 2) green cover estimates derived from a digital camera, and 3) reflectance measurements using a handheld radiometer. We calculated the optimum allocation of sampling effort to direct and indirect methods to minimize sampling cost yet achieve a desired precision. We found that the point frame technique explained the highest proportion of the variability in biomass at both sites (R² = 0.91, 0.90). However, our cost-optimization analysis revealed that the radiometer technique, although less accurate (R² = 0.38, 0.51), could achieve a desired precision for lower labor costs than the point frame. The radiometer and point frame methods will be a useful tool for grassland ecologists and rangeland managers who desire fast, nondestructive estimates of ANPP.     

Antagonists induce a conformational change in cIAP1 that promotes autoubiquitination

Inhibitor of apoptosis (IAP) proteins are negative regulators of cell death. IAP family members contain RING domains that impart E3 ubiquitin ligase activity. Binding of endogenous or small-molecule antagonists to select baculovirus IAP repeat (BIR) domains within cellular IAP (cIAP) proteins promotes autoubiquitination and proteasomal degradation and so releases inhibition of apoptosis mediated by cIAP. Although the molecular details of antagonist-BIR domain interactions are well understood, it is not clear how this binding event influences the activity of the RING domain. Here biochemical and structural studies reveal that the unliganded, multidomain cIAP1 sequesters the RING domain within a compact, monomeric structure that prevents RING dimerization. Antagonist binding induces conformational rearrangements that enable RING dimerization and formation of the active E3 ligase.     

Recent advances in the management of bovine tuberculosis in free-ranging wildlife

Established foci of Mycobacterium bovis (the causative agent of bovine tuberculosis [bTB]) in free-ranging wildlife are currently under various stages of management on three continents (Africa, Europe and North America) and in New Zealand. Other, as yet undiagnosed, foci seem likely to exist elsewhere. The complex roles that these wildlife foci play in the ecology of bTB remain among the greatest challenges facing bTB control globally. Conceptually, management of bTB in free-ranging wildlife can be thought of as progressing from the discovery of an outbreak through frequently overlapping stages of epidemiological characterization, initial control, simulation and forecasting, focused control, and verification of eradication. Surveillance in its various forms remains a critical component of assessment throughout. Since the Fourth International M. bovis Conference in 2005, research on management of bTB in free-ranging wildlife has encompassed such areas as the human dimensions of wildlife management, mitigation of bTB risks from wildlife on cattle farms, vaccine biology, and epidemiology, with a major contribution from simulation modeling. In order to advance the actual field management of bTB, however, research must be sufficiently grounded to aid development of practical, affordable and politically defensible management interventions which stand a reasonable chance of being implemented. The current management of two wildlife reservoirs of bTB, brushtail possums (Trichosurus vulpecula) in New Zealand, and white-tailed deer (Odocoileus virginianus) in Michigan, USA, serve as contrasting examples of different wildlife management strategies aimed at achieving a common goal. In New Zealand, the importance of agricultural export markets and the status of the possum as a non-native pest have facilitated direct, aggressive management of the disease reservoir, resulting in considerable progress towards bTB freedom since 1994. In Michigan, the relative importance of the hunting economy and of whitetails as a game animal have made such aggressive culling politically untenable. This has forced reliance upon publicly supported, and implemented, management tools, and so provided impetus to better understand social support for wildlife management policy, its limitations, and ways to employ it in disease control policy development.