The genus Pyrus L. (Rosaceae) in south-west Europe and North Afkica

A multivariate morphometric study of the genus Pyrus in south-west Europe and North Africa shows that five species may be recognized in the area: P. bourgaeana Decne., P. communis L., P. cordata Dew., P. spinosa Forssk, and P. nivalis Jacq. Some valuable characters for identification of these species are proposed. In particular the width of fruit peduncle, petal size, leaf width and petiole length served to discriminate the taxa. Several names such as P. gharbiona Trab., P. cossonii Rehder (|M= P. longipes Balansa ex Coss. & Durieu) and P. boisseriana Buhse, are regarded as synonyms of P. cordata , while P. marnormis Trab. of P. bourgaeana. Consequently a check-list and a key to these species are provided.     

Host range of a newly introduced parasitoid, Binodoxys communis among common aphid species in Hawaii

Binodoxys communis (Gahan) (Hymenoptera:Braconidae), a parasitoid of aphids originally from China, was introduced into Hawaii and evaluated in the laboratory for its ability to detect, accept, oviposit and develop in Aphis gossypii reared on two host plants, plus five other common aphid species. The parasitoid was able to detect all six aphid species and to successfully sting five species, with highest preference for those in the genus Aphis. Aphis species were highly suitable for parasitoid development. Other species were only marginally suitable. Parasitoids spent less time searching on plants of less acceptable aphids. Aphid defensive behaviors did not affect oviposition success, but did lengthen the parasitoid’s handling time of several aphid species. Host acceptance was positively correlated with host suitability, yet one unsuitable host was readily accepted for oviposition.     

Measuring ungulate tolerance to human with flight distance: a reliable visitor management tool?

Tourist-induced behavioural changes in large vertebrates are of concern for protected area management as they trigger a trade-off: large vertebrates attract visitors, but induced behavioral changes can reduce animal fitness and cause animals to avoid tourist-frequented zones. Behavioural response of animals to tourists is often studied to ensure informed management decision-making, a task frequently supported by flight distance analysis. In this context, guanaco (Lama guanicoe) response to tourists was studied in a protected area using two complementary methods: flight distance and sighting frequency analyses. Flight response analyses show that guanacos develop a considerable tolerance to vehicles and pedestrians in tourist areas, a reaction that extends approximately 500 m around visited areas. Such analyses thus point to (i) few areas being underused as a consequence of human presence and (ii) a low risk of tame animals being poached outside the park, all potentially leading to the conclusion that tourist visits are sustainable. However, guanaco sighting frequencies during 107 fieldwork days along 3 years show a significant reduction in sightings on days with higher Park visitor numbers. Moreover we present a formal procedure for the definition of a threshold for this to happen (247 visitors/day in our case). This suggests the potential risk of negative effects on guanaco population and a lower probability of guanaco sightings if Park visitor numbers rise beyond current figures. Results allow to conclude that assessment of human disturbance to flagship species in protected areas requires further methods in addition to flight distance.     

Lack of feral livestock interference with native guanaco during the dry season in a South American desert

Analyzing coexistence of exotic and native ungulates in arid areas is important from both a theoretical and a species conservation perspective. We assess the habitat use patterns and possible interference between guanaco (Lama guanicoe) and feral livestock (donkey and cattle) in arid environments of South America. To determine habitat use and niche overlap between exotic and native ungulate species, ten sites with different habitats and six natural waterholes were selected. Plots (20 at each site, ten around each waterhole) were randomly set up and characterized by environmental variables and relative use by cattle, donkey and guanaco through faecal pellet counts. Aggregation, niche breadth and niche overlap of the three herbivores were analyzed at habitat level (mesoscale). A direct redundancy analysis was used to examine the relationships between abundance of herbivore faeces and environmental variables at microscale. Mesoscale analyses showed (i) an extensive use of the area by all three species, with guanaco having the highest niche breadth followed by donkey and cattle and (ii) a large, broad guanaco–donkey and donkey–cattle habitat overlap. However, results at a finer scale showed high spatial aggregation of feral livestock species and an independent use of territory by guanacos. This study is the first to provide information about habitat partitioning between guanacos and feral livestock in the hyper-arid Monte Desert biome and points to an apparent lack of negative effects on the native ungulate.     

Improving the Oxidative Stability of a High Redox Potential Fungal Peroxidase by Rational Design

Ligninolytic peroxidases are enzymes of biotechnological interest due to their ability to oxidize high redox potential aromatic compounds, including the recalcitrant lignin polymer. However, different obstacles prevent their use in industrial and environmental applications, including low stability towards their natural oxidizing-substrate H₂O₂. In this work, versatile peroxidase was taken as a model ligninolytic peroxidase, its oxidative inactivation by H₂O₂ was studied and different strategies were evaluated with the aim of improving H₂O₂ stability. Oxidation of the methionine residues was produced during enzyme inactivation by H₂O₂ excess. Substitution of these residues, located near the heme cofactor and the catalytic tryptophan, rendered a variant with a 7.8-fold decreased oxidative inactivation rate. A second strategy consisted in mutating two residues (Thr45 and Ile103) near the catalytic distal histidine with the aim of modifying the reactivity of the enzyme with H₂O₂. The T45A/I103T variant showed a 2.9-fold slower reaction rate with H₂O₂ and 2.8-fold enhanced oxidative stability. Finally, both strategies were combined in the T45A/I103T/M152F/M262F/M265L variant, whose stability in the presence of H₂O₂ was improved 11.7-fold. This variant showed an increased half-life, over 30 min compared with 3.4 min of the native enzyme, under an excess of 2000 equivalents of H₂O₂. Interestingly, the stability improvement achieved was related with slower formation, subsequent stabilization and slower bleaching of the enzyme Compound III, a peroxidase intermediate that is not part of the catalytic cycle and leads to the inactivation of the enzyme.