The limitations of locust preventive management faced with spatial uncertainty: exploration with a multi‐agent model     

Pierre‐Emmanuel Gay  Michel Lecoq  Cyril Piou 《Pest management science》2020,76(3):1094-1102

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Identifying causes of low persistence of perennial ryegrass (Lolium perenne) dairy pasture using the Basic Grassland model (BASGRA)     

Simon J. R. Woodward  Marcel Van Oijen  Wendy M. Griffiths  Pierre C. Beukes  David F. Chapman 《Grass and Forage Science》2020,75(1):45-63

Recent years have seen a decline in herbage production and tiller populations in New Zealand's perennial ryegrass (Lolium perenne) dairy pastures. One hypothesis is that modern genotypes are less suited to the warmer, drier weather experienced under changing climate patterns. In this study, a combination of long-term trial data (2011–2017) and a process-based pasture model (BASGRA) was used to explore the causes and possible mitigation of the observed production and population loss at three sites (dryland sites in Northland and Waikato and an irrigated site in Canterbury). Bayesian calibration was used to identify the model parameter sets that were consistent with the trial data and to identify differences in plant morphology and responses between sites. The model successfully simulated the observed differences in tiller numbers between the dryland sites, where populations and production declined rapidly after the second year and the irrigated site where populations and production were maintained. Analysis of the model calibrations along with preliminary scenario simulations suggests that increased tiller mortality associated with drought was the main cause of persistence failure at the dryland sites and that decreasing grazing pressure or breeding for tolerance to higher temperatures may not be successful in preventing this.  相似文献   

Mitochondrial complex III Qi‐site inhibitor resistance mutations found in laboratory selected mutants and field isolates     

Pierre Mounkoro  Thomas Michel  Rafik Benhachemi  Georgiana Surpateanu  Bogdan I Iorga  Nicholas Fisher  Brigitte Meunier 《Pest management science》2019,75(8):2107-2114

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Effects of Mixing Conditions on Pasta Dough Development and Biochemical Changes     

Christle Icard-Vernire  Pierre Feillet 《Cereal Chemistry》1999,76(4):558-565

Mixing of commercial durum wheat semolina with water was performed under different conditions in a Brabender micromixer equipped with pastamaking shafts. Semolina filling of the mixing chamber was 30.4–42.9% (v/v), shaft speed was 10–110 rpm, temperature was 10–40°C, and hydration level was 47–52.5% (db). The blend of water and semolina evolved from individualized hydrated particles (HP) to a dough product (DP) as a function of these conditions. Torque values (T) and the specific mechanical energies (SME) were recorded during mixing as a function of time. Terms from these curves were defined to characterize the mixing process: t_o (starting time of dough development), t_d (time to reach the maximum dough consistency), T_m (mean torque value after dough development), and SME_f (total energy applied to the dough during mixing). Transformation of HP into DP and the mixing temperature were the main parameters affecting t_o, t_d, T_m, and SME_f. Protein aggregate distribution was measured by size-exclusion HPLC, protein solubility in 0.01N acetic acid, free -SH content, soluble arabinoxylans, reducing sugars, ferulic acid, carotenoid content, and oxidase activities to characterize the biochemical changes that occurred during pasta dough formation. DP was characterized by lower amounts of insoluble glutenin aggregates, lower protein solubility in dilute acetic acid, lower free -SH content, ferulic acid, carotenoid content, and lower oxidoreductase activities as compared to HP. Once the dough was developed, the effects of mixing speed, temperature, or hydration level on the biochemical composition of the blend were null or low compared to the modifications that were observed when the blends changed from HP to DP. The t_o and SME_f were the most significant parameters in characterizing the pasta dough mixing process in relation to biochemical changes.  相似文献   

A minimal model of the variability of marine ecosystems     

Christian Mullon  Pierre Fréon  Philippe Cury  Lynne Shannon  & Claude Roy 《Fish and Fisheries》2009,10(2):115-131

In marine ecology, population abundance time series often reveal patterns, such as decadal pseudo-cycles, on scales that make them difficult to mathematically characterize by means of conventional models based on functional responses. We propose here a simple non-deterministic model based on three strong ecological constraints, without any use of functional responses or external factors: (i) mass balance constraints between flows and biomass, (ii) a satiation constraint relating inflows and biomass and (iii) an inertia principle restricting the variation of populations of a given species according to its lifespan. This model reproduces in a robust manner observed patterns of variability and can be used to question the relevance of other modelling approaches of ecosystem dynamics with regard to determinism, constraints and stochasticity. Referring to a non-deterministic model without any functional relationships and environmental or anthropogenic forcing can help in avoiding misleading advice based on the belief that we can explain the causes of observed patterns, which may simply result from basic structural constraints within which the ecosystem functions.  相似文献   

Caroubin: A Gluten-like Protein Isolated from Carob Bean Germ     

Pierre Feillet  Thrse Marie Roulland 《Cereal Chemistry》1998,75(4):488-492

In 1935, Bienenstock and coworkers claimed the presence of gluten-like material in the germ of the carob seed. The viscoelastic properties of the water-insoluble proteins isolated from carob germ, which we propose to call caroubin, have been confirmed by dynamic (G′ and G″) and static rheological measurements (texture profile analysis, viscoelastogram). Biochemical analyses showed important similarities (high glutamic acid content, size-exclusion HPLC profile, PAGE patterns of reduced and unreduced proteins) as well as large differences (high arginine and low cysteine and proline content of caroubin, carbohydrate composition) between caroubin and wheat gluten. Besides potential new industrial uses of carob seed, caroubin could be a valuable material to help us understand the physicochemical basis of the viscoelastic properties of plant protein complexes like wheat gluten.  相似文献   

Inhibition of Methionine Biosynthesis in Botrytis cinerea by the Anilinopyrimidine Fungicide Pyrimethanil     

Rene Fritz  Catherine Lanen  Virginie Colas  Pierre Leroux 《Pest management science》1997,49(1):40-46

When mycelium of Botrytis cinerea was treated with low concentrations of the anilinopyrimidine fungicide pyrimethanil the total amount of free amino acids increased. Qualitative variations were also induced: alanine, glutamine, lysine, glycine, histidine, asparagine, arginine, threonine and moreover, α-aminobutyrate and β-alanine were accumulated; cyst(e)ine, valine, leucine and citrulline were reduced. When mycelium of B. cinerea was incubated with Na₂[³⁵S]O₄, pyrimethanil at 1·5 μM induced a decrease of [³⁵S]methionine and simultaneously an increase of [³⁵S]cystathionine. These data indicate that the anilinopyrimidine fungicide pyrimethanil inhibits the biosynthesis of methionine and suggest that the primary target could be the cystathionine β-lyase. © 1997 SCI.  相似文献   

Landscape patterns from mathematical morphology on maps with contagion     

Kurt Riitters  Peter Vogt  Pierre Soille  Christine Estreguil 《Landscape Ecology》2009,24(5):699-709

The perceived realism of simulated maps with contagion (spatial autocorrelation) has led to their use for comparing landscape pattern metrics and as habitat maps for modeling organism movement across landscapes. The objective of this study was to conduct a neutral model analysis of pattern metrics defined by morphological spatial pattern analysis (MSPA) on maps with contagion, with comparisons to phase transitions (abrupt changes) of patterns on simple random maps. Using MSPA, each focal class pixel on a neutral map was assigned to one of six pattern classes—core, edge, perforated, connector, branch, or islet—depending on MSPA rules for connectivity and edge width. As the density of the focal class (P) was increased on simple random maps, the proportions of pixels in different pattern classes exhibited two types of phase transitions at threshold densities (0.41 ≤ P ≤ 0.99) that were predicted by percolation theory after taking into account the MSPA rules for connectivity and edge width. While there was no evidence of phase transitions on maps with contagion, the general trends of pattern metrics in relation to P were similar to simple random maps. Using an index P for comparisons, the effect of increasing contagion was opposite that of increasing edge width.  相似文献   

The influence of landscape on insect pest dynamics: a case study in southeastern France   总被引：1，自引：0，他引：1  

Benoît Ricci  Pierre Franck  Jean-François Toubon  Jean-Charles Bouvier  Benoît Sauphanor  Claire Lavigne 《Landscape Ecology》2009,24(3):337-349

Managing the spatial distribution of crop and non-crop habitats over landscapes could be used as a means to reduce insect pest densities. In this study, we investigated whether or not landscape characteristics affected the number of codling moths in commercial orchards. To do this, we collected overwintering larvae in 2006 and 2007 in 76 orchards over a 70 km2 area in southeastern France. We analysed variations in the number of larvae using correlation tests and linear models. As independent variables, we took both characteristics of focus orchards (pear vs. apple, organic vs. conventional orchards) and of their surrounding landscape (orchard density and hedgerow network attributes) into account in buffers with widths varying from 50 to 500 m. Although the codling moth is specialised on orchards, the number of codling moths was lower in orchards within a high orchard density area. There was some indication that this effect was mostly due to the density of conventional orchards and thus to the intensity of insecticide treatments. Conversely, we found no particular effect of abandoned or organic orchards. In 2006, the number of codling moths was also significantly lower in a focus orchard when the hedgerow network acted as a protection against the prevailing wind. Finally, major effects of landscape variables on the number of codling moths were observed for distances of less than 150 m from the focus orchards, suggesting that codling moth management should be organised over areas of about 16 ha. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Landscape effects on the population dynamics of the fossorial form of the water vole (Arvicola terrestris sherman)     

Duhamel  Rémi  Quéré  Jean-Pierre  Delattre  Pierre  Giraudoux  Patrick 《Landscape Ecology》2000,15(2):89-98

The dynamics of microtine rodents show large variations among species and even among populations of a single species. Several studies have shown that landscape structure and predation play a role in these variations. We studied the influence of landscape structure on the spatial distribution and the population dynamics of the fossorial form of the water vole (Arvicola terrestris sherman). The sampling was based on a preliminary five-year survey of a rodent cycle on a regional scale, as well as a method of abundance estimation using surface indices. This survey led to distinguishing epicentres where outbreaks started, and diffusion sections where outbreaks occurred later. Results showed differences in dynamics of spatial distribution of the vole colonies between these two types of sections. This distribution pattern is related to landscape composition and structure. Epicentres are characterized by a higher ratio of open landscape, a lower ratio of forest, and less fragmentation when compared to the diffusion sections. Therefore landscape analysis has the potential of providing a valuable framework for the designing of programs for the early control of A. terrestris populations.  相似文献