Evidence for facultative protocarnivory in Capsella bursa-pastoris seeds

Many plants derive nutrients by attracting, ensnaring and killing invertebrates, a process that is described as “protocarnivory”. This has been observed in seeds of the weed Capsella bursa-pastoris, but it is unclear as to whether it confers any material benefit in terms of germination, establishment and development. In the present study, seeds were germinated in zero, low, medium and high nutrient soils in both the presence and absence of nematodes (Steinernema feltiae). Nematodes were attracted to the seeds, with many dying within three days. Germination rates and seedling fresh masses were higher at all nutrient levels, and seedling fresh lengths were higher in all but the zero nutrient treatment, in the presence of nematodes. After transplantation, young plant fresh root lengths and dried leaf and root masses were generally higher in plants that had been germinated in the presence of nematodes across all nutrient levels, with the majority of significant differences being observed in the low-nutrient treatment. Our findings suggest that protocarnivory may play a role in the germination, establishment and early development of C. bursa-pastoris, and that this process may be facultative, since differences between nematode and non-nematode treatments were generally more pronounced in soils with low nutrient levels

Factors affecting the local distribution of <i>Polystigma rubrum</i> stromata on <i>Prunus spinosa</i>

Background and aims – Polystigma rubrum forms orange-red stromata on the surface of living leaves of Prunus spinosa and P. domestica. Records suggests that this fungus now has a much more limited distribution in Britain than recorded in the 19th and early 20th century. Methods – We studied the local distribution of the fungus in the Burren Hills of western Ireland where it remains very common. Key results – Assessment of the local distribution of the fungus over two years found stromata to occur more frequently on P. spinosa leaves in hedgerows than woodlands. On individual trees in areas of open limestone pavement, the frequency of stromata was ten times higher in 2016 than 2015, possibly related to interannual rainfall differences. On hedgerow trees subjected to winter flooding, stromata were much less abundant, whereas stromata were more abundant on leaves also infected by the gall mite Eriophyes prunispinosae. The identity of Po. rubrum was confirmed by ITS sequencing.Conclusion – At a field location where Po. rubrum stromata are present in unusually high abundance, the distribution of stromata on trees in different habitats showed high levels of variation linked to both habitat and the presence of gall mites. Further work is required to determine whether variation in leaf surface and soil moisture are the key determinants of the observed distribution. Such investigations may reveal why Po. rubrum, once common in northern Europe is now restricted mainly to westerly, coastal locations

Teacher motivational messages used prior to examinations: what are they, how are they evaluated, and what are their educational outcomes?

A body of work has examined one of the key motivational messages used by teachers prior to high-stakes examinations, namely fear appeals. Fear appeals are persuasive messages designed to highlight the negative consequences of failure and the actions required to avoid failure. Based on models derived from the health promotion and stress appraisals literature, studies have examined how fear appeals are experienced by students and relate to important educational outcomes including motivation, emotion, engagement, and achievement. The aim of the present article was to review these studies and consider directions for future research. We propose that fear appeals represent a specific type of communicated value message that is loss-framed (i.e., focused on failure). We discuss a bidirectional model whereby fear appeals are indirectly related to educational outcomes through the way messages are evaluated by students. Educational outcomes can relate to subsequent evaluations and teacher use of messages in a reciprocal fashion. Gain-frame messages (messages focused on success), teacher-student relationships, distal background influences on message evaluations (e.g., socio-economic status), and alternative educational contexts (e.g., health professions education) are useful potential avenues for further studies to examine