34 research outputs found
Farmersâ management of functional biodiversity goes beyond pest management in organic European apple orchards
Supporting functional biodiversity (FB), which provides natural pest regulation, is an environmentally sound and promising approach to reduce pesticide use in perennial cultures such as apple, especially in organic farming. However, little is known about farmersâ practices and motivations to implement techniques that favor FB, especially whether or not they really expect anything from FB in terms of pest regulation. In fact, FB-supporting techniques (FB-techniques) are massively questioned by practitioners due to inadequate information about their effectiveness. An interview survey was performed in eight European countries(i) to describe farmersâ practices and identify promising FB-techniques: (ii) to better understand their perceptions of and values associated with FB; and (iii) to identify potential drivers of (non-)adoption. Fifty-five advisors and 125 orchard managers with various degrees of experience and convictions about FB were interviewed and a total of 24 different FB-techniques which can be assigned to three different categories (ecological infrastructures, farming practices and redesign techniques) were described. Some were well-established measures (e.g., hedges and bird houses), while others were more marginal and more recent (e.g., animal introduction and compost). On average, farmers combined more than four techniques that had been implemented over a period of 13 years, especially during their establishment or conversion period. In general, it was difficult for farmers to evaluate the effectiveness of individual FB-techniques on pest regulation. They considered FB-techniques as a whole, targeting multiple species, and valued multiple ecosystem services in addition to pest regulation. The techniques implemented and their associated values differed among farmers who adopted various approaches towards FB. Three different approaches were defined: passive, active and integrated. Their appraisal of FB is even more complex because it may change with time and experience. These findings provide empirical evidence that the practical implementation of promising techniques remains a challenge, considering the diversity of situations and evaluation criteria. Increased cooperation between researchers, farmers and advisors should more effectively target research, advisory support and communication to meet farmersâ needs and perceptions
Deforestation and apparent extinctions of endemic forest beetles in Madagascar
Madagascar has lost about half of its forest cover since 1953 with much regional variation, for instance most of the coastal lowland forests have been cleared. We sampled the endemic forest-dwelling Helictopleurini dung beetles across Madagascar during 2002â2006. Our samples include 29 of the 51 previously known species for which locality information is available. The most significant factor explaining apparent extinctions (species not collected by us) is forest loss within the historical range of the focal species, suggesting that deforestation has already caused the extinction, or effective extinction, of a large number of insect species with small geographical ranges, typical for many endemic taxa in Madagascar. Currently, roughly 10% of the original forest cover remains. Speciesâarea considerations suggest that this will allow roughly half of the species to persist. Our results are consistent with this prediction
Madagascan day geckos (Phelsuma spp.) exhibit differing responses along a gradient of land-use change
Madagascar is a key priority for global conservation efforts, as much of its diverse and highly endemic biota is threatened by deforestation. Despite this threat, there are limited data on the responses and tolerances of herpetofaunal species to landscape change. This study investigated the response of Madagascan day geckos (Phelsuma spp.) to deforestation in Nosy Be, Madagascar. We selected six sites along a gradient of land-use change: two in Sambirano rainforest (âForestâ), two in secondary, fragmented forest (âFragmentâ), and two in agricultural plantations (âOrchardâ and âCroplandâ). We conducted a series of time-constrained searches at each site. The mean encounter rate of Phelsuma geckos (geckos detected per person/hour) was greater in agricultural sites than Forest sites, but no difference was detected between Forest and Fragment or Fragment and agricultural areas. Three species were encountered more frequently in agricultural land than forested sites, but this was not true for Phelsuma seippi, an endangered species on the IUCN Red List. These results suggest that adaptive, generalist species may benefit from anthropogenic land-use change, whereas specialist species will suffer. Our study emphasizes the importance of extending research beyond the borders of protected forests to include anthropogenically disturbed areas
Unexpectedly diverse forest dung beetle communities in degraded rain forest landscapes in Madagascar
Tropical forests, which harbor high levels of biodiversity, are being lost at an alarming speed. Madagascar, a biodiversity hotspot, has lost more than half of its original forest cover. Most of the remaining forests are small fragments of primary and secondary forest with differing degrees of human impact. These forests, as well as coffee and fruit plantations, may be important in supporting the forest-dependent biodiversity in Madagascar but this has been little studied. In Madagascar, dung beetles, which offer important ecosystem services, are largely restricted to forests. We examined the ability of fragmented and degraded forests to support dung beetle diversity, compared to the large areas of primary forest in eastern Madagascar. We found a general trend of a reduction of species with a loss of forest connectivity. In contrast, a higher level of forest disturbance was associated with higher species diversity. In several sites of low-quality forest as many or more species were found as in less disturbed and primary forests. The average size of dung beetles was smaller in the lower quality localities than in the primary forests. These findings suggest that many forest dung beetles in Madagascar are better adapted to forest disturbance than earlier expected, although they require some level of connectivity to surrounding forest. in Malagasy is available with online material.Peer reviewe
An additive manufactured CubeSat mirror incorporating a novel circular lattice
Additive Manufacturing (AM; 3D printing) for mirror fabrication allows for intricate designs that can combine lightweight structures and integrated mounting. Conventional lightweight structures utilise cubic or prismatic unit cells, which do not provide uniform support at the edge of curved mirrors. We present a new circular lattice based upon cylindrical coordinates and how this lattice has been incorporated within an 80 mm diameter mirror intended for use in a 3U CubeSat telescope. Several design iterations are explored, which include prototype mirrors produced in a titanium alloy and a finite element analysis of the one of the design iterations
Rapid loss of flight in the Aldabra white-throated rail
Flight loss has evolved independently in numerous island bird lineages worldwide, and particularly in rails (Rallidae). The Aldabra white-throated rail (Dryolimnas [cuvieri] aldabranus) is the last surviving flightless bird in the western Indian Ocean, and the only living flightless subspecies within Dryolimnas cuvieri, which is otherwise volant across its extant range. Such a difference in flight capacity among populations of a single species is unusual, and could be due to rapid evolution of flight loss, or greater evolutionary divergence than can readily be detected by traditional taxonomic approaches. Here we used genetic and morphological analyses to investigate evolutionary trajectories of living and extinct Dryolimnas cuvieri subspecies. Our data places D. [c.] aldabranus among the most rapid documented avian flight loss cases (within an estimated maximum of 80,000â130,000 years). However, the unusual intraspecific variability in flight capacity within D. cuvieri is best explained by levels of genetic divergence, which exceed those documented between other volant taxa versus flightless close relatives, all of which have full species status. Our results also support consideration of Dryolimnas [cuvieri] aldabranus as sufficiently evolutionary distinct from D. c. cuvieri to warrant management as an evolutionary significant unit. Trait variability among closely related lineages should be considered when assessing conservation status, particularly for traits known to influence vulnerability to extinction (e.g. flightlessness)
Approche des facteurs de contamination des eaux souterraines par l'atrazine et la simazine. Cas des aquifĂšres de la Manche
La recherche de triazines a été effectuée dans l'eau de 149 captages du département de la Manche. Seules l'atrazine et la simazine ont été retrouvées et sur un faible nombre de points d'eau uniquement. Une étude statistique montre que les ouvrages dont les teneurs en atrazine ou en simazine sont supérieures au seuil de détection sont situés dans les terrains sédimentaires carbonatés. Les captages implantés dans les formations du socle semblent bénéficier d'une protection pouvant s'expliquer par la fixation des triazines par les argiles et par leur dégradation compte tenu de la faible perméabilité des terrains mais aussi pour partie en raison d'une moindre intensification agricole dans ces secteurs.
La recherche des métabolites de ces molécules s'avÚre cependant indispensable pour appréhender correctement les modalités de transfert de celles-ci
Palaeo-precipitation is a major determinant of palm species richness patterns across Madagascar: a tropical biodiversity hotspot
Amphibian Diversity in the Matrix of a Fragmented Landscape Around Ranomafana in Madagascar Depends on Matrix Quality
Conception et évaluation de systÚmes de culture maraßchers méditerranéens innovants pour gérer les nématodes à galles
Design and assessment of innovative Mediterranean vegetable cropping systems to manage root-knot nematodes. Description of the subject. A system approach based on co-design and experimental field evaluation of cropping systems (CSs), combining technical and varietal innovations, has been implemented for sustainable management of root-knot nematodes (RKN) in Mediterranean sheltered vegetable systems. Objectives. Cropping systems combining genetic resistance and cultural practices (crop rotations including susceptible, resistant, and non-host plants; intercropping management with nematicidal cover crops or soil solarization) were assessed over a period of 4 years (i) to reduce RKN populations and increase the durability of varietal resistances, (ii) to study the impact of these systems on soil ecology (plant-parasitic and free-living nematode communities), and (iii) to evaluate their acceptability by farmers. Method. Three CS prototypes, resulting from a co-design process with research and development stakeholders, were compared with CSs conventionally implemented in the Mediterranean region. The three prototypes were also evaluated using complementary methods: (i) system experiments in three commercial farms in Southern France; (ii) analytical experiments to decipher the mechanisms of action for some [agroecological??] levers; (iii) surveys to evaluate the acceptability of the prototypes by farmers. Results. All three CSs were found to be effective (90% RKN decrease, protection of partially resistant Solanaceae, no negative effect on non-phytoparasitic nematodes) and sustainable, when application conditions and soil biological equilibrium were favorable (global soil nematofauna diversified and abundant). The acceptability of the three systems depended on the type of farm where they were implemented and the attitude of the farmers towards innovation. Conclusions. These three CSs still need to be improved, in terms of their efficiency, in consultation with participating farmers, by introducing new agroecological levers, as well as innovation costs. Future research will also need to open up to a more comprehensive management of soil health