Rapid recovery of a depleted population of Little Bustards Tetrax tetrax following provision of alfalfa through an agri‐environment scheme

The Little Bustard has undergone a steep reduction of its Western Palaearctic range over the last century. In the west of France, breeding populations declined by 96% from 1978 to 2008 in cultivated areas where grasslands have been converted into intensively managed annual crops. Little Bustard abundance and nest productivity have been monitored since 1995 in a 450‐km² site in western France. We assessed the proximate causes of the decline of Little Bustards in French farming landscapes and quantified the effectiveness of conservation measures that aimed to reverse the decline. The decline of Little Bustard, from about 65 males in 1995 to just six males in 2003, could be related to a near absence of recruitment over this period. Since 2004, the establishment of more than 1300 ha of specifically targeted agri‐environment schemes (AES) in the study site has led to a sharp increase in female productivity, mainly associated with nesting in AES fields. By imposing constraints on mowing dates, AES have prevented nest destruction and female mortality during mowing and, by increasing plant species diversity, provided chicks with a higher abundance of grasshoppers. This has contributed to reversing the trend, and increasing the population to around 30 males in 2009. Conservation strategies involving specifically targeted AES based on the identification of limiting factors can help to reverse the decline of threatened species.     

Water deficit, root demography, and the causes of internal blackening in field-grown tomatoes:(Lycopersicon esculentum Mill.)

An internal blackening disorder may cause substantial losses in the value of tomatoes grown for processing. The disorder resembles an internal form of blossom-end rot and appears to be more common in dry seasons. In an experiment to test whether the internal blackening is caused by water deficit and whether it is indeed blossom-end rot, plots of cv. Cannery Row were irrigated to keep the soil moisture deficit <50 mm and others were sheltered from rain and not irrigated from early flowering onwards. Shoot growth (total and fruit dry mass) was measured destructively at intervals, and root growth and death nondestructively using minirhizotrons. There was a greater incidence of internal blackening and blossom-end rot, and lower Ca concentrations, in the fruit of non-irrigated plants. Root growth and root death were accelerated in these plants around the time that internally-blackened fruit were set. Although the internal blackening syndrome shared some features with blossom-end rot some differences were apparent in this experiment. It is suggested that internal blackening could have resulted from increased root competition for photosynthate, leading to abnormal seed development. Root turnover was appreciable (30–40% of the roots survived 28 days). This suggests there may be substantial errors in contemporary models of dry matter partitioning in tomato crops.     

The Plasma Membrane of Myxosporidian Valve Cells: Freeze Fracture Data

Freeze fracturing of Myxosporidian spores reveals the occurrence of a continuous layer of transmembrane particles all over the surface area of the valve cells which form the spore envelope. These particles are densely packed all over the P face membrane. Due to their polygonal outline, their diameter (6-7 nm) and their central core, they resemble the particles forming the connections of gap junctions which metabolically couple the neighboring cells in animal tissues. In the present report, the role of the transmembrane particles is still hypothetical. However, they might represent a membrane structural specialization of the spores which are submitted to osmotic variations of the fluid external medium. Furthermore similar transmembrane particles are observed at the level of the septate junction which seals the valve cells. In this occurrence, they are arranged in a series of 40 double rows parallel to the suture of the spore envelope. These findings support the view that Myxosporidia are Metazoa and raise the problem of their origin.     

Effect of local spatial plant distribution and conspecific density on bumble bee foraging behaviour

1. Size variations in pollinator populations may modify competitive interactions among foragers. Competition among pollinators has been shown to lead to one of two contrasting behaviours: either specialisation to the most profitable plant species or generalisation to several species. When foraging, pollinators are also confronted with heterogeneity in the spatial distribution of plant resources. Because variations in both the forager density and plant spatial distribution can affect pollinator behaviour, focus was on the interactive effect of these two factors. 2. Bumble bee (Bombus terrestris L.) individuals were trained on a focal species (Lotus corniculatus L.) and experimentally tested whether variations in the forager density (two or six bumble bees foraging together), plant community spatial distribution (two plant species: L. corniculatus and Medicago sativa, which were either patchily or randomly distributed), and their interaction modified bumble bee foraging behaviour. 3. It was shown that when confronted with a high forager density, bumble bees focused their visits towards the most familiar species, especially when foraging under a random plant distribution. These modifications affected the fruiting of the focal plant species, with a significantly lower reproductive success under low density/patchy conditions. 4. This study demonstrates that the foraging decisions of bumble bees are influenced by variations in both the conspecific density and plant spatial distribution. Given the increasing impact of human activities on plant‐pollinator communities, this raises the question of the potential implications of these results for plant communities in natural conditions when confronted with variations in the pollinator density and spatial distribution of plants.