Biochemical and physiological mechanisms underlying effects of Cucumber mosaic virus on host‐plant traits that mediate transmission by aphid vectors

The transmission of insect‐vectored diseases entails complex interactions among pathogens, hosts and vectors. Chemistry plays a key role in these interactions; yet, little work has addressed the chemical ecology of insect‐vectored diseases, especially in plant pathosystems. Recently, we documented effects of Cucumber mosaic virus (CMV) on the phenotype of its host (Cucurbita pepo) that influence plant‐aphid interactions and appear conducive to the non‐persistent transmission of this virus. CMV reduces host‐plant quality for aphids, causing rapid vector dispersal. Nevertheless, aphids are attracted to the elevated volatile emissions of CMV‐infected plants. Here, we show that CMV infection (1) disrupts levels of carbohydrates and amino acids in leaf tissue (where aphids initially probe plants and acquire virions) and in the phloem (where long‐term feeding occurs) in ways that reduce plant quality for aphids; (2) causes constitutive up‐regulation of salicylic acid; (3) alters herbivore‐induced jasmonic acid biosynthesis as well as the sensitivity of downstream defences to jasmonic acid; and (4) elevates ethylene emissions and free fatty acid precursors of volatiles. These findings are consistent with previously documented patterns of aphid performance and behaviour and provide a foundation for further exploration of the genetic mechanisms responsible for these effects and the evolutionary processes that shape them.     

The invasion and development of the cereal cyst-nematode, Heterodera avenae in the roots of autumn-and spring-sown cereals

Observations were made at 2 or 4 wk intervals from December to harvest on all stages of Heterodera avenae in winter oats growing on infested land. Second-stage larvae were present in all soil samples except on 5 and 20 July. Invasion and development of larvae was slow during winter. The nodal and seminal roots of winter oats were both heavily invaded by the nematode; larvae which invaded seminal roots tended to become male whereas those in nodal roots tended to become female. There was a small second invasion in August. Females were first observed on the roots of winter oats on 17 May, 214 days after the crop was sown and 62 days after the first fourth-stage larva was observed. The nodal roots of spring barley contained few H. avenae larvae whereas these roots were heavily invaded in winter wheat and oats. In spring barley the nodal roots were developing in June and July when few second-stage larvae were in the soil whereas in winter oats and wheat the nodal roots were growing rapidly in April when larvae were most numerous, and so were heavily invaded.     

SENSORY EVALUATION OF INDIAN-STYLE MARINATED CHICKEN BY MALAYSIAN AND EUROPEAN NAÏVE ASSESSORS

This study was carried out to determine the sensory acceptability of chicken breast fillets marinated with 13 different commercially available Indian-style marinades. Thirty-four naïve assessors (untrained panelists), 20 Malaysian and 14 European, were selected to assess the following sensory attributes: color, color uniformity, Tikka-Masala aroma, Tikka-Masala flavor, herblike flavor, hotness, authenticity, juiciness and overall acceptability. The color of the cooked samples and the pH, moisture and fat content of the marinades were analyzed instrumentally. Marinades were applied to the chicken fillets, which were then dry cooked at 170C for 15 min to an internal temperature of 73C. Sensory evaluation showed significant differences ( P <  0.05) in color uniformity, hotness and juiciness of the cooked marinated chicken perceived between groups. Samples marinated with marinades L and I received the highest score from the Malaysian panelists in terms of overall acceptability, whereas marinades A and F were chosen by the European group.

PRACTICAL APPLICATIONS

The findings from this research will benefit manufacturers of marinade and marinated chicken products in developing or optimizing their products for the local and international markets. The optimal characteristics of an ideal marinade were identified for each assessor group. These results are also of interest to individuals undertaking cross-cultural consumer studies, even though the results presented here used naïve assessors.     

Plant behavioural ecology: dynamic plasticity in secondary metabolites

Behaviour is in part the ability to respond rapidly and reversibly in response to environmental stimuli during the lifetime of an individual. Plants and animals both exhibit behaviour, but plant behaviour is most often examined in the context of morphologically plastic growth. Rapid and reversible secondary metabolite production and release is also a key mechanism by which plants behave. Here, we review plant biochemical plasticity as plant behaviour, and explicitly focus on evidence for responses that display rapid induction, reversibility and ecological relevance. Rapid induction and attenuation of plant secondary metabolites occur as chemically mediated root foraging, plant defence, allelochemistry and to regulate mutualistic relationships. We describe a wealth of information on the induction of various plant biochemical responses to environmental stimuli but found a limited body of literature on the reversibility of induced biochemical responses. Understanding the full cycle of dynamic plasticity in secondary metabolites is an important niche for future research. Biochemical behaviours extend beyond the plant kingdom; however, they clearly illustrate the capacity for plants to behave in ways that closely mirror the classic definitions and research approaches applied to behaviour in animals.     

Applications of stable isotope techniques to the ecology of mammals

• 1 Stable isotope analysis (SIA) has the potential to become a widespread tool in mammalian ecology, because of its power in resolving the ecological and behavioural characteristics of animals. Although applications of the technique have enhanced our understanding of mammalian biology, it remains underused. Here we provide a review of previous applications to the study of extant mammals, drawing when appropriate on examples from the wider ecological literature, to identify the potential for future development of the approach.
• 2 Stable isotope analysis has been applied successfully to understanding the basic foraging decisions of mammals. However, SIA generates quantitative data on a continuous scale meaning that the approach can be particularly powerful in the characterization of community metrics, such as dimensions of resource partitioning within species assemblages or nutrient dynamics in food chains. Resolving spatial and temporal patterns of individual, intraspecific and interspecific resource use is of fundamental importance in animal ecology and evolutionary biology and SIA will emerge as a critical tool in these fields.
• 3 Geographical differences in naturally occurring stable isotopes have allowed ecologists to describe large‐scale mammal migrations. Several isotopic gradients exist at smaller spatial scales, which can provide finer resolution of spatial ecology.
• 4 A combination of foraging and movement decisions is of prime importance in the study of ecotoxicology, since this discipline requires quantitative understanding of exposure risk.