Le fil des saisons vu de l'espace

Vue d’un satellite, le fil des saisons est déjà perceptible, et plus particulièrement au travers de la présence de la végétation. Ainsi, les images pourront être d’autant plus colorées en rouge que la végétation exprimera son activité photosynthétique. Au contraire, le sol nu et les bâtiments apparaitront de couleur cyan. Il est alors possible d’observer le cycle de la Nature depuis l’espace et de déduire le cycle des cultures

Adaptation aux paysages agricoles européens d’une méthode cartographique d’analyse de la configuration et de la composition des cultures

Les paysages agricoles occupent près de 40% de la superficie des terres disponibles. A ce titre, ils jouent un rôle important dans la conservation de la biodiversité. En retour, cette dernière contribue à la production agricole en fournissant des services écosystémiques tels que la pollinisation ou la lutte biologique. Le rôle de l'hétérogénéité du paysage agricole dans le maintien de la biodiversité se révèle être une piste de recherche intéressante qui pourrait suggérer de nouvelles politiques agricoles visant à favoriser la biodiversité. Le projet FARMLAND (BiodivERsa2011-66) s’insère dans ce contexte en s'inspirant de travaux récents combinant des outils de géomatique, de télédétection et de géostatistique. Sur la base du calcul d'indices spatiaux, ces travaux proposent une méthode pour réaliser la sélection de quadrats permettant de considérer l'influence sur la biodiversité, de l'hétérogénéité de composition du paysage (nombre et proportions des différents types de couvert) et de l'hétérogénéité de configuration (arrangement spatial des types de couvert). Ce projet doit aboutir à la sélection d'une cinquantaine de carrés dans 7 sites européens au sein desquels seront effectués des relevés de biodiversité et des évaluations des services écosystémiques. Nous présentons les différentes étapes de la méthode cartographique (classification et segmentation d'image satellitaire, analyse par fenêtre mobile, requête multicritère) menant à la réalisation du plan d'échantillonnage pour le site des Vallées et Coteaux de Gascogne qui sert de zone test pour les autres sites européens. Nous discutons des adaptations nécessaires et des différences avec le site de référence canadien

Temporal patterns of emergence, calling behaviour and oviposition period of the maize stem borer, Busseola fusca (Fuller) (Lepidoptera : Noctuidae)

Sexual behaviour in most of the noctuid Lepidoptera follows a diel periodicity and is limited to a precise period of either the day or the night. The periodicity and the maturation periods are specific as well as the onset of oviposition behaviour. The knowledge of these traits of biology is an essential prerequisite for all the studies in chemical ecology. The periodicity of adult emergence, calling behaviour and oviposition of Busseola fusca (Fuller) was studied under laboratory conditions. Most males emerged before onset of the scotophase whereas most females did so one hour later. The virgin females started to exhibit calling behaviour few hours after emergence and there is no sexual maturation time. The calling behaviour starts the fourth hour after the onset of the scotophase but is lightly delayed for females having emerged the same night as compared to older females. Sexual and oviposition behaviours occur during the dark period. Oviposition started the first night after the mating night, peaked during the second night and then gradually decreased until the fifth night. The first night of oviposition, females laid eggs during the first three hours and after the 5(th) hour of the scotophase with a maximum during the 8(th) and 9(th) hour. During the second night, oviposition peaked during the second hour and tended to decrease thereafter

Distribution, pest status and agro-dimatic preferences of lepidopteran stem borers of maize in Kenya

Lepidopterous stem borers are the main field insect pests that attack maize, Zea mays L. in tropical Africa. A survey was carried during the long and short rain cropping seasons of 2002/2003 across six main agro-climatic zones (ACZs) to determine the spatial distribution of important stem borer species in Kenya. A total of 474 visits were made in the seventy-eight localities conveniently chosen to represent each of the six ACZs. 189,600 stems were checked for infestation, of which 27,799 infested stems were destructively cut and dissected for stem borer larvae identification. An average of 1.4 stem borer larvae were recovered per infested plant. 54.5% of the recovered larvae were identified as Chilo partellus (Swinhoe) (Crambidae), 39.7% as Busseola fusca (Fuller) (Noctuidae), 4.5% as Sesamia calamistis Hampson (Noctuidae) and 0.8% as Chilo orichalcociliellus (Strand) (Crambidae). Minor species present included Eldana saccharina Walker (Pyralidae), Sesamia nonagrioides (Lefebvre) (Noctuidae), Sesamia cretica Lederer (Noctuidae), Sesamia sp. (Noctuidae), Sciomesa piscator Fletcher (Noctuidae), Busseola sp near phaia (Noctuidae), Chilo sp, Ematheudes sp 1 (Pyralidae) and Ematheudes sp 2 (Pyralidae). Farms were grouped into respective ACZs for statistical analysis and subsequent comparison of dominant species: Results indicated that B. fusca was the dominant stem borer species in high potential zones (highland tropics, moist transitional zone and moist mid-altitude) while the exotic C. partellus dominated smallholder farms in low potential zones (dry mid-altitude, dry transional and lowland tropical zone). Within each ACZs, there was evidence of variation in species proportions between seasons. These spatio-temporal differences in community structure are discussed in terms of agro-climatic biological adaptations

Гранитоиды обрамления Криворожской структуры. Проблемы корреляции геологических тел и комплексов

Current population genetic models fail to cope with genetic differentiation for species with large, contiguous and heterogeneous distribution. We show that in such a case, genetic differentiation can be predicted at equilibrium by circuit theory, where conductance corresponds to abundance in species distribution models (SDM). Circuit-SDM approach was used for the phylogeographic study of the lepidopteran cereal stemborer Busseola fusca Füller (Noctuidae) across sub-Saharan Africa. Species abundance was surveyed across its distribution range. SDM models were optimized and selected by cross validation. Relationship between observed matrices of genetic differentiation between individuals, and matrices of resistance distance was assessed through Mantel tests and redundancy discriminant analyses (RDA). A total of 628 individuals from 130 localities in 17 countries were genotyped at 7 microsatellite loci. Six population clusters were found based on a Bayesian analysis. The eastern margin of Dahomey Gap between East and West Africa was the main factor of genetic differentiation. The SDM projections at present, last interglacial and last glacial maximum periods were used for estimation of circuit resistance between locations of genotyped individuals. For all periods of time, when using either all individuals or only East-African individuals, partial Mantel r and RDA analyses conditioning on geographic distance were found significant. Under future projections (year 2080), partial r and RDA significance were different. From this study, it is concluded that analytical solutions provided by circuit theory are useful for the evolutionary management of populations and for phylogeographic analysis when coalescence times are not accessible by approximate Bayesian simulations

Connectivité spatiale et diversité des espèces: Mise en place d’un réseau de conservation dans le Parc National du Mercantour

La thématique des forêts anciennes et des forêts matures a été au cœur du séminaire physique du GT Forêt-Eau, avec l'organisation le 27 octobre 2015 d'une journée d'échanges et de visite, associant une douzaine de partenaires (INRA, IRSTEA, Purpan, RNF, FPNR, CBNMC...). Au delà, PNF [Parcs Nationaux de France] continuera à suivre les différents projets en cours, menés par des Parcs nationaux ou d'autres partenaires, et à envisager d'autres projets collectifs pour aller plus loin dans la connaissance des forêts anciennes et matures

Increasing crop heterogeneity enhances multitrophic diversity across agricultural regions

International audienceAgricultural landscape homogenization has detrimental effects on biodiversity and key ecosystem services. Increasing agricultural landscape heterogeneity by increasing seminatural cover can help to mitigate biodiversity loss. However, the amount of seminatural cover is generally low and difficult to increase in many intensively managed agricultural landscapes. We hypothesized that increasing the heterogeneity of the crop mosaic itself (hereafter “crop heterogeneity”) can also have positive effects on biodiversity. In 8 contrasting regions of Europe and North America, we selected 435 landscapes along independent gradients of crop diversity and mean field size. Within each landscape, we selected 3 sampling sites in 1, 2, or 3 crop types. We sampled 7 taxa (plants, bees, butterflies, hoverflies, carabids, spiders, and birds) and calculated a synthetic index of multitrophic diversity at the landscape level. Increasing crop heterogeneity was more beneficial for multitrophic diversity than increasing seminatural cover. For instance, the effect of decreasing mean field size from 5 to 2.8 ha was as strong as the effect of increasing seminatural cover from 0.5 to 11%. Decreasing mean field size benefited multitrophic diversity even in the absence of seminatural vegetation between fields. Increasing the number of crop types sampled had a positive effect on landscape-level multitrophic diversity. However, the effect of increasing crop diversity in the landscape surrounding fields sampled depended on the amount of seminatural cover. Our study provides large-scale, multitrophic, cross-regional evidence that increasing crop heterogeneity can be an effective way to increase biodiversity in agricultural landscapes without taking land out of agricultural production