Land use alters the abundance of herbivore and predatory insects on crops: the case of alfalfa

We assess the effects of changing land use and crop management on alfalfa insect abundance by comparing it in 50 alfalfa fields when they were inserted in landscapes with different proportions of arable crops and orchards. Land use in a buffer of 500 m was assessed, and alfalfa insect abundance was estimated with sticky yellow traps. The number of catches of several herbivores and predators was related to the proportion of landscape components and several field variables. Results indicated that the proportion of orchards in the buffer negatively affected the abundance of predators on alfalfa, likely because orchards treated with pesticides are a sink for predators moving in the landscape, among other possible causes. Other landscape variables such as noncrop habitats, winter cereals, and landscape diversity analysed by the Shannon index had a minor influence. Among field variables, field size influenced positively the abundance of insects on alfalfa, whereas alfalfa growth stage and age affected positively or negatively the different herbivores and predators. Of course, abundance of predators and prey was affected by the abundance of prey and predators, respectively. These findings suggest that a high proportion of intensively managed crops (orchards) in the landscape interferes with the role of alfalfa as a reservoir of predatory insects for adjacent crops and that the responses to local and landscape structures are temporal and species-specific as previously concluded for maize. Consequently, landscape and field management strategies to improve pest control must consider both types of variables as well as their changing influence when we modify them.

     

Are neighboring trees in tune? Wood formation in Pinus pinaster

Neighboring trees growing under identical environmental conditions can exhibit different dynamics and periods of growth. Despite the recent advances in cambial biology, the exogenous and endogenous factors generating asynchronous xylem growths still remain undetermined. This study investigated timings and duration of xylem formation in maritime pine (Pinus pinaster Ait.) from an even-aged plantation in Portugal growing under Mediterranean climate. Cambial phenology and stem diameter were monitored weekly, from March to December 2010, on two classes of trees divided according to the tree ring widths of the last 15 years, but similar age and size: fast- and slow-growing trees. We tested the hypothesis that differences in tree ring widths result from cell production which in turn affects timings of xylogenesis and that the bimodal growth pattern, typical of the Mediterranean, originates from a double reactivation of the cambium: in spring and autumn. Cambial activity started earlier and ended later in fast-growing trees, confirming that cell production is a key factor determining the duration of xylogenesis. Intra-annual variations in stem diameter recorded by band dendrometers revealed two peaks of increment occurring in spring and late summer. However, the number of cambial cells did not increase in late summer, which suggested that the second peak of increment was caused by stem rehydration, rather than by a reactivation of cell division. These results demonstrated that the variability in the timings of xylem phenology observed among trees of the same age and size and growing under similar environmental conditions was closely related to cell production and not to age or size per se.     

Selection index based on random regression model in ‘Tahiti’ acid lime

Euphytica - Drought tolerance in maize is a complex and polygenic trait, especially in the seedling stage. In plant breeding, complex genetic traits can be improved by genomic selection (GS), which...     

Fish invading deserts: non‐native species in arid Moroccan rivers

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Effects of deer on the post-fire recovery of a Mediterranean plant community in Central Portugal

We studied the effect of dense populations of red and fallow deer on a burned Mediterranean plant community in Portugal. We sampled a set of 12 open and 12 fenced plots 2, 3, 4, and 8 years after fire occurrence. Each plot was sub-sampled using a quadrat grid to estimate the relative plant frequency (proportion of quadrats with plants). The effect of deer on temporal trends of overall plant frequency and diversity, and on the abundance of the four most common woody species, was modeled using Generalized Linear Mixed Models. The effect of deer on plant assemblage composition was assessed by use of Redundancy Analysis. In open plots the relative plant frequency increased along the study period from 0.59 to 0.85, whereas in fenced plots there was a significantly faster recovery from 0.35 to 0.96. Cistus salvifolius and Rubus ulmifolius were significantly favored by fencing but a similar effect was not observed for Erica scoparia and Ulex jussiaei. The Redundancy Analysis showed a divergent floristic composition of the two sets of plots. The effect of deer was significant for the Evenness index but not for the Shannon and the Richness indices. Our results show that a high deer density may significantly delay the post-fire recovery of a Mediterranean community of woody plants and cause shifts in the direction of plant succession.     

Indications and Techniques for Blood Transfusion in Birds

There is growing medical care related to emergency presentations and procedures used to treat companion and wild birds. These critical care procedures (e.g., blood transfusion) can be life-saving. To maximize the beneficial effects of blood transfusions administered to avian patients, it is necessary to have an understanding of avian hematology and erythropoiesis, recognize clinical conditions in which one performs a blood transfusion, know the proper procedures and techniques, and rapidly identify possible adverse reactions.