Face or flee? Fenitrothion resistance and behavioral response in populations of the maize weevil, Sitophilus zeamais

Insect survival in the presence of contact insecticides may be through physiological mechanisms or avoidance of contact with the compound. Curiously, although the first alternative is the object of frequent attention, the second is often neglected, but both may lead to insecticide resistance. Preliminary evidence for both physiological and behavioral resistance to pyrethroids has been obtained for a few strains of the maize weevil Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae). Here we carried out a more comprehensive survey using 15 populations of S. zeamais, by examining a long-used but relatively little studied organophosphate - fenitrothion, recording not only physiological resistance, but also the behavioral responses to exposure. Physiological resistance to fenitrothion among populations of S. zeamais reached low to moderate levels (ranging from 0.9 to 14.1× at the LC₅₀), an increase in resistance levels compared with previous studies. Fenitrothion-induced behavioral avoidance varied among populations, particularly regarding insecticide irritability (i.e., avoidance after contact with fenitrothion), but the behavioral responses observed were mainly stimulus-independent. However, there was no correlation between physiological and behavioral resistance to fenitrothion in S. zeamais populations. Both survival strategies to fenitrothion - facing or fleeing the insecticide exposure, were observed and may co-occur in a single population, emphasizing the need of assessing both responses and their relative importance in designing management programs against stored-product insects.     

Moving in the right direction? The role of price subsidies in fertilizer use and maize productivity in Ghana

Despite major maize programs in the last two decades and costly investments in a price subsidy program in Ghana, maize productivity remains very low. Utilizing cross-sectional data on 645 maize plots in Ghana, this paper provides empirical evidence on the responsiveness of maize yield to fertilizer application, profitability of fertilizer use, and how the economics of fertilizer use have changed with the subsidy program. There was a statistically significant maize yield response to increased fertilizer application (i.e. 1-kg of nitrogen leads to a yield increase of 22–26 kg per hectare), higher than those estimated in other countries in Africa. Value-cost ratio shows that maize production with fertilizer is profitable both at market and subsidized prices in different locations and with different farming practices, even after incorporating risk into the estimation and analysis. However, despite subsidized prices and profitable fertilizer use, the actual application rate (at 44 kg/ha of nitrogen on average) is much lower than research institute’s and government recommendation and far off the computed economically “optimal” levels (at 225 kg/ha of nitrogen; where the fertilizer price intersects the value of marginal physical product derived from the yield response model). Results suggest that fertilizer prices do not seem to be the binding constraint in greater fertilizer application and productivity increases in maize; other factors appear to be major bottlenecks to greater fertilizer application and productivity increases including accessibility to modern varieties, mechanization, and hired labor. This result shows the limits to fertilizer subsidy as the focus strategy and suggests a more integrated and holistic approach to encourage greater fertilizer application, productivity and income among maize farmers in Ghana.     

A 100-Year Review: Animal welfare in the Journal of Dairy Science—The first 100 years

This paper outlines the history and development of research in the area of animal welfare as reflected in the 100 yr that the Journal of Dairy Science has been published. The first paper using the term “animal welfare” was published in 1983; since then (to May 2017), 244 papers that reflect growing interest regarding how farm animals are cared for have been published. Much of the scientific work to date has focused on issues related to cow health, such as lameness, and methodologically many papers use behavioral measures. In addition to this science-based research, the journal has taken on the role of publishing work of social scientists that addresses the role of the human factors relating to animal welfare, including research on citizen, consumer, and farmer attitudes toward welfare issues. We call for further research focused on societal perspectives and for new biological research focused on developing issues, such as cow–calf separation and pasture access.     

Is there a link between dietary phytoestrogens and reproductive health in men? A meta‐analysis of data from the USA and China

The human health implications of exposure to environmental pollutants and food components (e.g. phytoestrogens) that mimic the female hormone 17β‐estradiol (xenoestrogens) are a subject of significant debate. In this study, we use published data on human dietary phytoestrogen intake and sperm concentrations in the USA and China to assess effects on sperm concentration as a marker of male reproductive health. Comparison of the phytoestrogen intake and sperm concentration trends shows that in the USA phytoestrogen intake has increased from 0.8 mg day^?1 in 1993 to 13.7 mg day^?1 in 2005 and sperm concentration is trending down (not statistically significant), whereas in China phytoestrogen intake has decreased from 64.7 mg day^?1 in 1991 to 15.6 mg day^?1 in 2008, and the sperm concentration has increased from 55 × 10⁶ mL^?1 in 1999 to 74 × 10⁶ mL^?1 in 2008. We present this as evidence that phytoestrogen intake via food might, at least in part, be responsible for sperm concentration trends.     

Identification of an acidic α-amylase from Alicyclobacillus sp. A4 and assessment of its application in the starch industry

An acidic α-amylase was purified from thermoacidophilic Alicyclobacillus sp. A4 by ion exchange chromatography with 22% recovery, and showed a molecular mass of 64 kDa by SDS-PAGE. Its amino acid sequence was determined by sequencing three internal peptides and the complete genome of strain A4, and shared highest identity (64%) with Alicyclobacillusacidocaldarius α-amylase. Compared with other reported α-amylases, the purified enzyme had some distinct characteristics. The optimal activity was found to occur at 75 °C and pH 4.2, similar to the glucamylase widely used in the starch industry. The enzyme was Ca²⁺ independent, and had strong ability to digest raw starch (96.71%) with commercial glucamylase in one step. These properties of the purified enzyme make up the deficiency of the commercial α-amylases currently used and avoid repeated adjustment of pH and temperature in double-enzymatic sugar-making process. The purified enzyme will be commercially valuable in the starch industry.     

The impact of chitosan film or chitosan/chitosan–epigallocatechin gallate conjugate composite film on the quality changes of Asian sea bass (Lates calcarifer) slices stored in air or under vacuum packaging

Quality and shelf-life of Asian sea bass slices (ASBS) wrapped with chitosan (CS)/CS–epigallocatechin gallate (CE) conjugate composite or CS films and packaged in air or under vacuum during storage at 4 °C were studied. Total viable count was less than permissible limit (6 log·CFU g⁻¹ sample) for ASBS wrapped with CS/CE conjugate composite film under vacuum (ASBS-COMP-VP) after 18 days. Moreover, lower microbial proliferation and volatile base contents were attained in ASBS-COMP-VP sample than other samples during the storage (P < 0.05). At the end of storage, ASBS-COMP-VP sample had lower lipid oxidation than those wrapped with CS film (P < 0.05). Polyunsaturated fatty acid content of ASBS-COMP-VP was retained at higher content at day 18. Therefore, ASBS-COMP-VP had the enhanced shelf-life with high acceptability up to 18 days at 4 °C, while ASBS wrapped with CS film and packaged in air or under vacuum had the shelf-life of 9 and 12 days, respectively.     

A comparative study of physicochemical and conformational properties in three vicilins from Phaseolus legumes: Implications for the structure–function relationship

The polypeptide constituents, physicochemical and conformational properties of three vicilins from kidney, red and mung beans, fractionated using combined acid extraction and ion-exchange chromatographic techniques, were characterized and compared. The tested physicochemical and conformational properties included amino acid composition, surface charge and hydrophobicity, protein solubility (PS; as a function of pH), emulsifying activity index (EAI) and emulsion stability index (ESI), as well as secondary, tertiary and/or quaternary conformations. The amino acid composition (especially relative acidic/basic charged amino acid ratio, and the percentage of polar uncharged amino acids) was an intrinsic physicochemical parameter that largely determined other physicochemical and conformational properties. The PS and EAI (and ESI) of these vicilins at various pH values were associated with each other, and both were closely related to their surface charge and/or hydrophobicity. Far-UV CD spectral analyses indicated that these vicilins exhibited similar secondary structure compositions at pH deviating from the isoelectric point (about pH 4.5). However, their tertiary and/or quaternary conformations, as determined by differential scanning calorimetry, intrinsic fluorescence and near-UV CD spectroscopy, remarkably varied. At pH 7.0 or 9.0, there were close relationships between the EAI and the flexibility in quaternary conformation, and between the ESI and the flexibility in tertiary conformation. This is the first observation to elucidate the importance of tertiary and/or quaternary conformations for the emulsifying properties of legume vicilins. Additionally, an underlying mechanism of the emulsification process for the vicilins (trimeric form) with excellent emulsifying properties was proposed.     

A new antimicrobial glucosinolate autolysis product, 4-isothiocyanatobutanoic acid,from the diffuse wallflower (Erysimum diffusum): Methyl 4-isothiocyanatobutanoate,a long unrecognized artifact of the isolation procedure?

A GC–MS analysis of Erysimum diffusum Ehrh. (Brassicaceae) glucosinolate autolysis products led to the identification of a new mustard oil constituent – 4-isothiocyanatobutanoic acid. The identity of the new glucosinolate breakdown product was confirmed by means of co-injection of the synthetic compound in the GC with the root autolysate and derivatization reaction to the well known methyl ester. Methyl ester of this acid was long believed to be a genuine glucosinolate hydrolysis product but we now provide evidence that it could be an artifact of the isolation procedure. 4-Isothiocyanatobutanoic acid was assayed for antimicrobial activity and demonstrated significant inhibitory (10–220 μg/ml) and microbicidal (10–1175 μg/ml) activity against important human pathogens.