Search results for " life science"
showing 10 items of 12151 documents
Use of solid state fermentation to produce Beauveria bassiana for the biological control of european corn borer
1993
The production process of a new bioinsecticide against european corn borer is described. The entomopathogenic fungus, Beauveria bassiana, is cultivated by Solid State Fermentation (SSF). The culture support chosen, clay microgranules, humidified with optimal nutritive solution, is incubated in optimal conditions during 48 hours, then dried for 5 days. The bioinsecticide can be directly used after harvesting, without formulation. This process is original for several reasons : - The granulometry (500 microm) and the bulk density (0.6) of the microgranules are compatible with the mechanical standard application of pesticides on corn. - The bioinsecticide could be produced in a pilot reactor of…
Modularity as a source of new morphological variation in the mandible of hybrid mice.
2012
Abstract Background Hybridization is often seen as a process dampening phenotypic differences accumulated between diverging evolutionary units. For a complex trait comprising several relatively independent modules, hybridization may however simply generate new phenotypes, by combining into a new mosaic modules inherited from each parental groups and parts intermediate with respect to the parental groups. We tested this hypothesis by studying mandible size and shape in a set of first and second generation hybrids resulting from inbred wild-derived laboratory strains documenting two subspecies of house mice, Musmusculus domesticus and Musmusculus musculus. Phenotypic variation of the mandible…
Mycelial development of Fusarium oxysporum in the vicinity of tomato roots
1999
The patterns of mycelial development (length and branching) of five strains of Fusarium oxysporum were measured in the vicinity of tomato and wheat roots. Two strains were of f. sp. lycopersici, two of f. sp. radicis-lycopersici and the fifth was a non-pathogenic strain currently used as a biocontrol agent. Hyphal extension and branching were measured microscopically using a CCD camera and an image analyser. Furthermore, the role of soluble root exudates, insoluble root materials, glucose supply, and nitrogen supply (casamino acids) on mycelial development was investigated. Each strain had its own pattern of development in the absence of a root. Fungal development of all five strains was st…
Fitness of backcross six of hybrids between transgenic oilseed rape (Brassica napus) and wild radish (Raphanus raphanistrum
2002
The process of introgression between a transgenic crop modified for better agronomic characters and a wild relative could lead potentially to increased weediness and adaptation to the environment of the wild species. However, the formation of hybrid and hybrid progeny could be associated with functional imbalance and low fitness, which reduces the risk of gene escape and establishment of the wild species in the field. Our work compares the fitness components of parents and different types of backcross in the sixth generation of hybrids between transgenic oilseed rape (Brassica napus, AACC, 2n = 38) resistant to the herbicide glufosinate and wild radish (Raphanus raphanistrum, RrRr, 2n = 18)…
Ectosymbiosis is a critical factor in the local benthic biodiversity of the Antarctic deep sea.
2008
10 pages; International audience; In deep-sea benthic environments, competition for hard substrates is a critical factor in the distribution and diversity of organisms. In this context, the occurrence of biotic substrates in addition to mineral substrates may change the characteristics of sessile fauna. We tested this hypothesis at different localities of the Weddell Sea (Antarctica) by studying the diversity of ectosymbionts living on the spines of cidaroids (echinoids). The presence of cidaroids promoted a higher total specific richness and increased sessile species abundance, but did not change the diversity. Analyses of species distribution suggested that the cidaroids are a favourable …
Comparative biogeography of echinoids, bivalves and gastropods from the Southern Ocean.
2013
ABSTRACTAim Biogeographical patterns within three classes, the Echinoidea, Bivalvia andGastropoda, were investigated in Antarctic, sub-Antarctic and cold-temperateareas based on species occurrence data. Faunal similarities among regions wereanalysed to: (1) test the robustness of the biogeographical patterns previouslyidentified in bivalves and gastropods; (2) compare them with the biogeographi-cal patterns identified for echinoids; and (3) evaluate the reliability of the bio-geographical provinces previously proposed, depending on the taxa andtaxonomic levels analysed.Location The Southern Ocean, sub-Antarctic islands and cold-temperate areassouth of 45° S latitude at depths of < 1000 m.Meth…
Assessing larval food quality for phytophagous insects: are the facts as simple as they appear?
2006
9 pages; International audience; We argue here that host plant quality affects many life-history traits of herbivorous insects and these traits often interact. Studies that look only at a limited number of traits often fail to determine the overall effect of plant quality on larval performance and adult fitness. Parameters such as mating success and adult longevity are frequently neglected even though they are affected by larval feeding and are crucial to overall fitness. To illustrate this, we examined a whole suite of life-history traits of the moth Lobesia botrana after rearing larvae of this grape pest on three different grape cultivars. Development time, mating success, fecundity, egg …
A preliminary approach for modelling the effects of cropping systems on the dynamics of broomrape ( Phelipanche ramosa) in interaction with the non-p…
2011
International audience; The current decrease in herbicide use may increase and diversify weed flora in crops as well as companion bioagressors spreading via weeds. Among these bioagressors is Phelipanche ramosa (L.) Pomel, a parastic plant which is very harmful on oilseed rape. The objective of the present work was to develop a new model (called PheraSys) of the effects of cropping systems on parasite dynamics, in interaction with non-parasitic weed hosts. The structure of this first model version was based on models developed for other parasitic plants and on FlorSys which quantifies the effects of cropping systems on non-parasitic weed flora. PheraSys was parametrized with preliminary val…
Demographic responses of a site-faithful and territorial predator to its fluctuating prey: long-tailed skuas and arctic lemmings.
2014
Summary1. Environmental variability, through interannual variation in food availability or climaticvariables, is usually detrimental to population growth. It can even select for constancy in keylife-history traits, though some exceptions are known. Changes in the level of environmentalvariability are therefore important to predict population growth or life-history evolution.Recently, several cyclic vole and lemming populations have shown large dynamical changesthat might affect the demography or life-histories of rodent predators.2. Skuas constitute an important case study among rodent predators, because of theirstrongly saturating breeding productivity (they lay only two eggs) and high deg…
Environmental impacts on wetland birds: long-term monitoring programmes in the Camargue, France.
2010
10 pages; International audience; Wetlands in the Mediterranean area have become a rare habitat due to human impact. To model the ecology and breeding biology of birds depending on that habitat, we describe long-term studies on two wetland birds (Little Egret Egretta garzetta and Greater Flamingo Phoenicopterus (ruber) roseus) in the Camargue, France. The hydrological conditions in natural Mediterranean wetlands depend largely on the pattern of rainfall (winter) and evapotranspiration (summer), but have been substantially altered by human activities. In natural conditions, these wetlands are very diverse and therefore sustain a high diversity of breeding birds. At the same time their unpred…