A fructose‐based extender protects Colossoma macropomum spermatozoa against chilling injuries

Our study assessed the efficiency of a formulated new extender in maintaining viability and morphological integrity of Colossoma macropomum spermatozoa under chilling storage. Semen was diluted in the test extender and BTS? (Beltsville Thawing Solution) and exposed to a short‐term storage at 4.6 ± 0.6°C for 96 hr. Both extenders were able to maintain 17% ± 8% motile spermatozoa by the end of experiment. Sperm dilution in test extender did not affect the morphologically normal cells (61% ± 6%) up to 48 hr of chilling, being higher than in BTS? (50% ± 6%) (p < 0.05). After 96 hr, samples kept in the test extender had 50% of normal spermatozoa, whereas those kept in BTS? presented only 38% of normal cells. Chilling storage increased the incidence of cells with strongly coiled flagella in BTS^?. Our study is the first to evaluate in detail the spermatozoa morphology as indicative of C. macropomum semen viability. The new extender was able to protect the spermatozoa against increase in coiled flagellum injuries.     

A broad diversity survey of Rhizoctonia species from the Brazilian Amazon reveals the prevalence of R. solani AG-1 IA on signal grass and the new record of AG-1 IF on cowpea and soybeans

Leaf blight, sheath blight, and web blight are major diseases caused by Rhizoctonia species on both Fabaceae and Poaceae plant hosts in the Brazilian Amazon agroecosystem. To determine the diversity of Rhizoctonia species associated with foliar diseases on fabaceous (cowpea and soybean) and poaceous (rice and signal grass [Urochloa brizantha]) hosts, a broad survey was conducted in Pará, Rondônia, Roraima, and Mato Grosso, in the Amazon, from 2012 to 2013. We extended our survey to Cerrado areas of Mato Grosso, and the lowlands of Paraíba Valley, in São Paulo, where these Rhizoctonia foliar diseases have not been reported so far. Our findings revealed that these diseases are caused by a diversity of Rhizoctonia solani AG-1 complex. We detected that R. solani AG-1 IA (sexual phase Thanatephorus cucumeris) was the predominant pathogen associated with signal grass leaf blight and collar rot diseases in the Amazon, especially in Rondônia and northern Mato Grosso. In addition, a subgroup of R. solani (AG-1 IF), not previously reported in Brazil, was associated with leaf blight on cowpea and soybean, in Roraima. Another subgroup (AG-1 ID) was also detected in Roraima. In Mato Grosso Cerrados we did not find any of the major Rhizoctonia foliar pathogens. Instead, R. oryzae (Waitea circinata) was the predominant species associated with a collar rot on U. brizantha. In the lowlands of São Paulo, R. oryzae-sativae (Ceratobasidium oryzae-sativae) was the predominant pathogen detected causing the rice sheath spot disease.     

Antipredator responses to overhead fright stimuli in hatchery-reared and wild European sea bass (Dicentrarchus labrax L.) juveniles

In this study, shoals of hatchery‐reared and wild sea bass juveniles (Dicentrarchus labrax L.) were tested for differences in their antipredator responses towards a visual (shadow) and a mechanical (dummy bill) overhead stimulus. Two behavioural variables – distance from the bottom and freezing duration – were measured during post‐stimulus phases of each test and compared between wild and hatchery‐reared shoals, composed of 10 juveniles each. The results showed that in both hatchery‐reared and wild juveniles, stimulus exposure elicited a significant decrease in the mean shoal distance from the bottom. Similarly, individuals from both groups engaged a freezing reaction, but the mean freezing duration was significantly higher in wild‐ than in hatchery‐reared juveniles. Results are discussed in the light of their relevance for the enhancement of restocking programmes.     

Modelling the impact of agricultural abandonment and wildfires on vertebrate diversity in Mediterranean Europe

Agricultural land abandonment, widespread in the Mediterranean, is leading to a recovery of scrubland and forests which are replacing open habitats and increasing wildfire events. Using published data, we modelled the global and regional impact of abandonment and wildfires on 554 species of terrestrial vertebrates occurring in Mediterranean Europe. For all groups except amphibians, open habitats or farmland sustained higher species richness. Open habitats showed regional differences in their conservation value, western areas being particularly important for birds and amphibians and eastern areas for reptiles. Scrublands hosted fewer species than open habitats, farmland and forest, but sustained several endemic birds and mammals. The greater species richness of forests was mostly due to species widespread in Europe. Wildfires promote scrubland expansion in detriment of forest; because more species are associated to eastern forests, fire is predicted to affect more seriously this region. Scrubland conservation value was found to be highest in the west, where fire might have a positive impact. Fire regime, however, plays a crucial role. Although large fires have a negative impact, small-scale fires may favour biodiversity in abandoned areas. Due to the intrinsic difficulty in managing abandoned land to preserve the original Mediterranean vertebrate diversity, the best option to achieve this goal is the development of policies designed to make farmers and traditional farmland survive.