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Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, and Fundamental and applied biological sciences. Psychology

The effects of secondary metabolites in different Vigna species on the development of Clavigralla tomentosicollis were investigated in an artificial seed system using different fractions of crude pod extracts, while the orientation response of this pod-bug to volatile extracts was studied using a dual-choice olfactometer. Feeding on the neutral fraction extracts, in contrast to the basic and acidic fractions, resulted in significantly higher mortalities, longer total developmental time, and lower growth index of the insects in comparison with controls. All volatile extracts elicited an avoidance reaction by C. tomentosicollis, except the volatile from the susceptible genotype IT84S-2246 which generally attracted as many insects as controls. Extracts from wild Vigna species showed higher activity than those from their cultivated relatives. The present study which has established that most secondary metabolites in cowpea pods were localized in the neutral fraction of the crude extract, could facilitate experiments on the separation and characterization of the toxic factors involved.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Phytopathologie. Zoologie agricole. Protection des cultures et des forets, Phytopathology. Animal pests. Plant and forest protection, Protozoaires. Invertébrés, Protozoa. Invertebrates, Signalements, symptômes, dégâts, importance économique, surveillance des populations, Records, symptoms, damages, economic importance, population surveys, Angiospermae, Arthropoda, Coreidae, Dicotyledones, Déprédateur, Pest, Plaga, Heteroptera, Insecta, Invertebrata, Leguminosae, Légumineuse grain, Grain legume, Leguminosa grano, Relation animal végétal, Animal plant relation, Relación animal vegetal, Spermatophyta, Comportement alimentaire, Feeding behavior, Conducta alimenticia, Comportement déprédateur, Pest behavior, Conducta depredadora, Culture tropicale, Tropical crop, Cultivo tropical, Cycle développement, Life cycle, Ciclo desarrollo, Etude en laboratoire, Laboratory study, Estudio en laboratorio, Glycine max, Hôte substitution, Host substitution, Huesped sustitución, Plante hôte, Host plant, Planta huesped, Survie, Survival, Sobrevivencia, Vigna unguiculata, and Clavigralla tomentosicollis

Suitability of the pods of cowpea (Vigna unguiculata (L.) Walp) and soybean (Glycine max (L.) Merrill) as food for Clavigralla tomentosicollis was determined in the laboratory using development, food substitution and host switch experiments. On soybean pods, nymphs survived for 8 days and adults for 12 days; on cowpea, all nymphal instars developed into adults and lived for 80-100 days. Teneral adults that were switched from cowpea to soybean lost weight, while adults that were moved from soybean to cowpea gained weight with slight differences between the sexes. The shortest critical survival threshold (duration with at least 50% survival) of adults on cowpea was greater than the longest on soybean. The likelihood of C. tomentosicollis exploiting soybean as a trophic niche in areas of tropical Africa where production of this crop is on the increase and usually contiguous with cowpea production, is discussed.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Agronomie. Sciences du sol et productions vegetales, Agronomy. Soil science and plant productions, Génétique et amélioration des plantes d'intérêt économique, Genetics and breeding of economic plants, Sélection variétale. Amélioration spéciale, objectifs d'amélioration, Varietal selection. Specialized plant breeding, plant breeding aims, Résistance aux organismes nuisibles, Pest resistance, Déprédateurs, Pest animals, Amélioration génétique, Genetic improvement, Enriquecimiento genético, Angiospermae, Arthropoda, Coreidae, Culture tropicale, Tropical crop, Cultivo tropical, Dicotyledones, Déprédateur, Pest, Plaga, Fruit, Fruto, Heteroptera, Insecta, Invertebrata, Leguminosae, Légumineuse grain, Grain legume, Leguminosa grano, Plante sauvage, Wild plant, Planta salvaje, Spermatophyta, Comparaison interspécifique, Interspecific comparison, Comparación interespecífica, Cultivar, Dégât, Damage, Estrago, Effet dimensionnel, Size effect, Efecto dimensional, Etude en laboratoire, Laboratory study, Estudio en laboratorio, Gousse, Pod, Vaina, Graine, Seeds, Semillas, Infestation, Infestación, Lignée sélection, Breeding line, Línea selección, Mécanisme défense, Defense mechanism, Mecanismo defensa, Ressource génétique, Genetic resource, Recurso genético, Résistance insecte, Insect resistance, Resistencia insecto, Trichome, Tricoma, Vigna unguiculata, Clavigralla tomentosicollis, Péricarpe, Pericarp, and Vigna vexillata

Studies were conducted in the laboratory to investigate the different components of the resistance of Vigna vexillata A. Richards, TVnu 72, and several cultivars of cultivated Vigna spp. to infestation and damage by the brown cowpea coreid, Clavigralla tomentosicollis Stäl. The main objective was to determine the different roles of the pod wall and seeds, and the relationship between seed size, number, and damage by this insect. Results showed that both the pod wall and seed clearly contribute different components to the resistance of TVnu 72 to C. tomentosicollis. Analysis of the results suggests that the seed defences and the pod wall pericarp may be more important than are trichomes in this resistance. Seed number was found to influence the extent of damage in a more predictable manner than seed size. However, because both of these traits are generally inversely related and mutually exclusive, their individual effects cannot be completely separated. The implications of these traits in a breeding programme targeted at a specific consumer group are discussed.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Invertebres, Invertebrates, Ecologie animale, vegetale et microbienne, Animal, plant and microbial ecology, Ecologie animale et végétale, Animal and plant ecology, Autoécologie, Autoecology, Animaux, Animals, Protozoa. Invertebrata, Angiospermae, Arthropoda, Dicotyledones, Heteroptera, Insecta, Invertebrata, Leguminosae, Spermatophyta, Déprédateur, Pest, Plaga, Développement, Development, Desarrollo, Etude en laboratoire, Laboratory study, Estudio en laboratorio, Fécondité, Fecundity, Fecundidad, Lens culinaris, Longévité, Longevity, Longevidad, Pentatomidae, Pisum sativum, Plante hôte, Host plant, Planta huesped, Plante légumière, Vegetable crop, Planta leguminosa, Relation animal végétal, Animal plant relation, Relación animal vegetal, Reproduction, Reproducción, and Thyanta pallidovirens

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Agronomie. Sciences du sol et productions vegetales, Agronomy. Soil science and plant productions, Génétique et amélioration des plantes d'intérêt économique, Genetics and breeding of economic plants, Sélection variétale. Amélioration spéciale, objectifs d'amélioration, Varietal selection. Specialized plant breeding, plant breeding aims, Résistance aux organismes nuisibles, Pest resistance, Déprédateurs, Pest animals, Africa, Angiospermae, Arthropoda, Dicotyledones, Heteroptera, Insecta, Invertebrata, Leguminosae, Spermatophyta, Afrique, Coreidae, Criblage, Screening, Cernido, Déprédateur, Pest, Plaga, Etude en laboratoire, Laboratory study, Estudio en laboratorio, Etude en serre, Greenhouse study, Estudio en invernadero, Etude sur terrain, Field study, Estudio en campo, Lignée sélection, Breeding line, Línea selección, Méthode, Method, Método, Méthodologie, Methodology, Metodología, Nigéria, Nigeria, Origine végétale, Plant origin, Origen vegetal, Plante légumière, Vegetable crop, Planta leguminosa, Relation animal végétal, Animal plant relation, Relación animal vegetal, Résistance insecte, Insect resistance, Resistencia insecto, Sensibilité résistance, Sensitivity resistance, Sensibilidad resistencia, Vigna unguiculata, Pest resistance, Clavigralla tomentosicollis, and Résistance déprédateur

Description des procédures de criblage destinées à tester la résistance de nouvelles accessions de niébé, et qui peuvent être appliquées pour le criblage rapide de germoplasmes et la séparation des lignées de sélection.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, Ecology, Ecologie, Geology, Géologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Ecologie animale, vegetale et microbienne, Animal, plant and microbial ecology, Ecologie microbienne, Microbial ecology, Milieux divers (espace extraatmosphérique, air, eau), Various environments (extraatmospheric space, air, water), Bactérie, Bacteria, Article synthèse, Review, Artículo síntesis, Cyanobacteria, Cycle biogéochimique, Biogeochemical cycle, Ciclo biogeoquímico, Diazotrophie, Diazotrophy, Diazotrofía, Fixation azote, Nitrogen fixation, Fijación nitrogeno, Milieu marin, Marine environment, Medio marino, Océan, Ocean, Océano, and Trichodesmium

The surface water of the marine environment has traditionally been viewed as a nitrogen (N) limited habitat, and this has guided the development of conceptual biogeochemical models focusing largely on the reservoir of nitrate as the critical source of N to sustain primary productivity. However, selected groups of Bacteria, including cyanobacteria, and Archaea can utilize dinitrogen (N2) as an alternative N source. In the marine environment, these microorganisms can have profound effects on net community production processes and can impact the coupling of C-N-P cycles as well as the net oceanic sequestration of atmospheric carbon dioxide. As one component of an integrated 'Nitrogen Transport and Transformations' project, we have begun to re-assess our understanding of (I) the biotic sources and rates of N2 fixation in the world's oceans, (2) the major controls on rates of oceanic N2 fixation, (3) the significance of this N2 fixation for the global carbon cycle and (4) the role of human activities in the alteration of oceanic N2 fixation. Preliminary results indicate that rates of N2 fixation, especially in subtropical and tropical open ocean habitats, have a major role in the global marine N budget. Iron (Fe) bioavailability appears to be an important control and is, therefore, critical in extrapolation to global rates of N2 fixation. Anthropogenic perturbations may alter N2 fixation in coastal environments through habitat destruction and eutrophication, and open ocean N2 fixation may be enhanced by warming and increased stratification of the upper water column. Global anthropogenic and climatic changes may also affect N2 fixation rates, for example by altering dust inputs (i.e. Fe) or by expansion of subtropical boundaries. Some recent estimates of global ocean N2 fixation are in the range of 100-200 Tg N (1-2 x 1014 g N) yr-1, but have large uncertainties. These estimates are nearly an order of magnitude greater than historical, pre-1980 estimates, but approach modern estimates of oceanic denitrification.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, Ecology, Ecologie, Geology, Géologie, Sciences exactes et technologie, Exact sciences and technology, Terre, ocean, espace, Earth, ocean, space, Sciences de la terre, Earth sciences, Géochimie, Geochemistry, Géochimie des sols et des roches, Soil and rock geochemistry, Formations superficielles, Surficial geology, Quaternaire marin et continental, Marine and continental quaternary, Europe, Europa, Actuel, modern, Actual, Calcium, calcium, Calcio, Carbohydrate, carbohydrates, Matière particulaire, particulate matters, Partícula elemental, Milieu intertidal, intertidal environment, Medio intertidal, Particule, particles, Rhéologie, rheology, Reología, Sorption, sorption, Sorción, Stabilisation, stabilization, Estabilización, Sédimentation estuaire, estuarine sedimentation, Sedimentación estuario, Vasière, mud flats, and Marisma

Extracellular Polymeric Substances (EPS) are considered to play an important role in the stabilization of intertidal mudflats. In this study the role of EPS as a binding agent in intertidal sediments was investigated. For this purpose two EPS fractions (termed coll-SF and EDTA-SF) were isolated from intertidal sediment and characterized in terms of monosaccharide- and size distribution. In slurry addition experiments the sorption characteristics of these EPS-fractions as well as their effect on sediment properties were examined under varying Ca2+-concentrations. Results showed more EDTA-SF adsorbed to the sediment compared to coll-SF. For both fractions more EPS adsorbed to the sediment when Ca2+-concentration increased. This effect was stronger for EDTA-SF. The differences in sorption between the two fractions could not be explained in terms of monosaccharide- and size distribution, which were largely similar. The addition of EPS in the presence or absence of Ca2+ did not alter the rheology of the sediment slurries indicating that there was no effect of EPS on the sediment properties. This contradicts results of experiments with bacterial EPS as well as field observations in which the presence of EPS/ biofilms leads to an increase in the erosion resistance of the sediment. Possible causes for this discrepancy in results are discussed.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Ecology, Ecologie, Entomology, Entomologie, Environment, Environnement, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Ecologie animale, vegetale et microbienne, Animal, plant and microbial ecology, Ecologie appliquée, Applied ecology, Ecotoxicologie, effets biologiques de la pollution, Ecotoxicology, biological effects of pollution, Action de la pollution et effets secondaires des pesticides sur les protozoaires et les invertébrés, Effects of pollution and side effects of pesticides on protozoa and invertebrates, Phytopathologie. Zoologie agricole. Protection des cultures et des forets, Phytopathology. Animal pests. Plant and forest protection, Protozoaires. Invertébrés, Protozoa. Invertebrates, Généralités, Generalities, Lutte, Control, Angiospermae, Arachnida, Arthropoda, Gramineae, Insecta, Invertebrata, Monocotyledones, Spermatophyta, Acephate, Araneida, Carbophenothion, Cypermethrine, Cyrthorhinus lividipennis, Delphacidae, Deltamethrine, Dose létale 50, Lethal dose 50, Dosis letal 50, Déprédateur, Pest, Effet secondaire, Secondary effect, Efecto secundario, Endosulfan, Entomophage, Entomophagous, Entomofago, Ethylan, Heteroptera, Homoptera, Insecticide, Lycosa pseudoannulata, Microvelia atrolineata, Nilaparvata lugens, Oryza sativa, Osbac, Plante céréalière, Cereal crop, Prédateur, Predator, Predador, Toxicité, Toxicity, and Toxicidad

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Plant biology and physiology, Biologie et physiologie végétales, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Bactériologie, Bacteriology, Métabolisme. Enzymes, Metabolism. Enzymes, Ecologie animale, vegetale et microbienne, Animal, plant and microbial ecology, Ecologie animale et végétale, Animal and plant ecology, Autoécologie, Autoecology, Végétaux et champignons, Plants and fungi, Activité enzymatique, Enzymatic activity, Actividad enzimática, Bactérie, Bacteria, Cyanobacteria, Enzyme, Enzima, Facteur milieu, Environmental factor, Factor medio, Oxidoreductases, Phytoplancton, Phytoplankton, Fitoplancton, Chlorophylle, Chlorophyll, Clorofila, Eclairement énergétique, Irradiance, Aclaramiento energético, Fixation azote, Nitrogen fixation, Fijación nitrogeno, Flottabilité, Buoyancy, Flotabilidad, Intégration numérique, Numerical integration, Integración numérica, Milieu marin, Marine environment, Medio marino, Modèle mathématique, Mathematical model, Modelo matemático, Nitrogenase, Photosynthèse, Photosynthesis, Fotosíntesis, Variation journalière, Daily variation, Variación diaria, and Aphanizomenon

Measurements were made of the rates of nitrogenase activity (acetylene reduction) by cyanobacteria collected from the Baltic Sea at 2-h intervals, over a period of 24 h, and incubated under natural light. By relating the chlorophyll-specific rate of N2 fixation (PN) to the mean photon irradiance (I) at different periods, a PN/I curve was constructed. A mathematical description of this relationship was used in the calculation of rates of N2 fixation at different depths and times of day from continuous measurements of surface irradiance and light attenuation. By relating these calculations to the vertical distribution of chlorophyll due to Aphanizomenon flos-aquae, an estimate of the daily integral of N2 fixation by the population of this cyanobacterium was obtained: it varied from 039 to 071 mmol m-2 with a mean value of 053 mmol m-2 over 9 d. Comparisons with similar calculations of the daily integral of photosynthesis over the same period indicated the atomic ratio of N/C fixed is about 022, not very different from the N/C ratio expected for the elemental composition of these cyanobacteria. It is demonstrated that when buoyant gas-vacuolate colonies float up during calm periods the increased irradiance that they experience supports an increased rate of N2 fixation. This increase is less than that seen for carbon fixation because photosynthesis is negated by respiration at low irradiances and is less inhibited at high irradiances.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Plant biology and physiology, Biologie et physiologie végétales, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Ecologie animale, vegetale et microbienne, Animal, plant and microbial ecology, Ecologie microbienne, Microbial ecology, Milieux divers (espace extraatmosphérique, air, eau), Various environments (extraatmospheric space, air, water), Bactérie, Bacteria, Cyanobacteria, Aphanizomenon flosaquae, Croissance, Growth, Crecimiento, Flottabilité, Buoyancy, Flotabilidad, Milieu marin, Marine environment, Medio marino, Photosynthèse, Photosynthesis, Fotosíntesis, Phytoplancton, Phytoplankton, Fitoplancton, Répartition verticale, Vertical distribution, Distribución vertical, and Vésicule gaz

Observations were made on the vertical distribution of colonies of Aphanizomenon flos-aquae for 9 d at a driftstation east of Bornholm Island in the Baltic Sea. The buoyant colonies were dispersed in the upper layers of the water column during periods of wind-induced mixing but floated up during calm periods. From measurements of the vertical light extinction, surface irradiance and the photosynthesis versus irradiance curve, calculations were made of the changes in the daily integral of photosynthesis with respect to time and depth throughout the water column. From these calculations it is demonstrated that net photosynthesis by the population of Aphanizomenon flos-aquae increased nearly threefold by floating up after a deep mixing event. It is estimated that, averaged over alternating periods of calm and mixing, the buoyancy provided by gas vesicles in this organism will result in a nearly twofold increase in photosynthesis. A quantitative analysis has been made of the relationship of the daily integral of photosynthesis by the Aphanizomenon population with the mean depth of the population in the water column and the daily insolation. The analysis shows that the integral decreases linearly with respect to mean depth.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Ecologie animale, vegetale et microbienne, Animal, plant and microbial ecology, Ecologie animale et végétale, Animal and plant ecology, Autoécologie, Autoecology, Végétaux et champignons, Plants and fungi, Synécologie, Synecology, Ecosystèmes terrestres, Terrestrial ecosystems, Angiospermae, Arthropoda, Composé allélochimique, Allelochemicals, Aleloquímicos, Entomophage, Entomophagous, Entomófago, Gramineae, Heteroptera, Hymenoptera, Insecta, Invertebrata, Monocotyledones, Pentatomidae, Scelionidae, Spermatophyta, Attraction, Atracción, Chimiotactisme, Chemotaxis, Quimiotactismo, Composé volatil, Volatile compound, Compuesto volátil, Déprédateur, Pest, Plaga, Kairomone, Kairomona, Oryza sativa, Parasitoïde, Parasitoid, Parasitoide, Plante céréalière, Cereal crop, Planta cerealista, Relation animal végétal, Animal plant relation, Relación animal vegetal, Système tritrophique, Tritrophic system, Sistema tritrófico, Sécrétion défensive, Defensive secretion, Secreción defensiva, Trissolcus basalis, Platygastridae, Telenomus podisi, Tibraca limbativentris, kairomone, rice plants, semiochemical, and stink bug

The rice stem bug, Tibraca limbativentris Stal. (Hemiptera: Pentatomidae) is one of the most important pests of rice crops, especially irrigated crops. Plant defence strategies against these bugs may involve the emission of chemical compounds, which are released following herbivore attacks, directly or indirectly harming pest performance. The aim of this study was to evaluate the influence of constitutive and herbivory-induced volatiles from rice plants (Oryza sativa L.) on the behavioural responses of T. limbativentris adults and egg parasitoids Trissolcus basalis (Wollaston) and Telenomus podisi (Ashmead) (Hymenoptera, Platygastridae). Plant volatiles were collected from undamaged plants of the rice cultivar IRGA 424 and from plants that suffered herbivory by five males or five females of T. limbativentris. Air-entrainment extracts were analysed by GC―flame ionization detector and GC-MS, and insect responses evaluated in a 'Y' olfactometer. T. limbativentris feeding damaged on rice plants induced the release of 16 volatiles compounds in a higher amounts compared to undamaged plants The main compounds induced were (E)-2-hexenal, (E)-2-octen-1-ol, methyl salicylate and α-muurolene. Female bugs were significantly attracted to air-entrainment extracts containing volatiles from undamaged plants compared with air-entrainment extracts containing volatiles emitted from plants damaged by T. limbativentris, whereas males showed no preference. Telenomus podisi females were significantly attracted to volatiles from air-entrainment extracts of plants damaged by females, whereas T. basalis showed no preference. These results suggest that rice plants may be emitting defence compounds, which could be avoided by T. limbativentris females and also acted indirectly by attracting natural enemies.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Phytopathologie. Zoologie agricole. Protection des cultures et des forets, Phytopathology. Animal pests. Plant and forest protection, Protozoaires. Invertébrés, Protozoa. Invertebrates, Lutte, Control, Lutte chimique, Chemical control, Angiospermae, Arthropoda, Gramineae, Invertebrata, Monocotyledones, Pesticide, Pesticides, Plaguicida, Plante céréalière, Cereal crop, Planta cerealista, Spermatophyta, Zone tropicale, Tropical zone, Zona tropical, Date de plantation, Planting date, Fecha de plantación, Déprédateur, Pest, Plaga, Fertilisation azotée, Nitrogen fertilization, Fertilización nitrogenada, Infestation, Infestación, Insecta, Insecticide, Insecticida, Irrigation, Irrigación, Lutte antidéprédateur, Pest management, Manejo de plagas, Lutte chimique, Chemical control, Lucha química, Oryza sativa, Prise décision, Decision making, Toma decision, Rendement, Yield, Rendimiento, Résistance insecte, Insect resistance, Resistencia insecto, Seuil intervention, Action threshold, Umbral tratamiento, Pest control, colonisation pattern, decision making, insecticides, irrigated rice, nitrogen fertilisation, plant tolerance, planting date, and yield loss

Action thresholds as decision tools for insecticide application were developed and tested against the major insect pests of rice at four sites in the Philippines over a 13-year period. Action threshold treatments were compared to the farmers' practice, prophylactic insecticide usage, and an untreated check. Yield loss data using the insecticide check method partitioned yield losses over three crop growth stages in the same test fields. Chronic pests that exceeded action thresholds in 79% of fields were whorl maggot Hydrellia philippina Ferino (Diptera: Ephydridae), defoliators Naranga senescens Moore and Rivula atimeta (Swinhoe) (Lepidoptera: Noctuidae), leaffolders Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley (Lepidoptera: Pyralidae), and stemborers Scirpophaga incertulas (Walker) and S. innotata (Walker) (Lepidoptera: Pyralidae). Minor chronic pests reached threshold levels in only one site each: rice bug Leptocorisa oratorius (F.) (Koronadal), whitebacked planthopper Sogatella furcifera (Horvath) (Zaragoza) and green leafhopper Nephotettix virescens (Distant) (Guimba); brown planthopper Nilaparvata lugens (Stål) did not exceed a threshold in any field. Stemborers were the most important pest group in terms of yield loss. Despite the insecticide check method underestimating losses, a mean crop loss of 0.62 t/ha was measured which showed ample scope for corrective action. But loss was evenly distributed across crop growth stages (0.15 0.24 t/ha) reducing the impact of insecticides. Action threshold treatments overall outyielded the untreated check, more so in the two sites with highest pest density. The benefit of thresholds was to reduce insecticide usage, as a cost saving. However all the practices showed poor economic returns including the farmers' practice. Farmers' practice employed low insecticide dosages and timing was not consistent with pest damage, but yields were often similar to threshold treatments. Farmers appear to use insecticide more for risk aversion than for profit. The best threshold characters when evaluated against resulting pest density and yield loss criteria showed accuracies > 90% correct decisions. Future work is needed to improve the insecticide response rather than monitoring tools. Thresholds need to be incorporated into improved crop management, which was often found suboptimal by farmers, to take advantage of the high levels of tolerance in modern high tillering cultivars. Crop husbandry practices which improve yield potential such as selection of longer maturing varieties and nitrogen fertilizer may be a more effective pest management strategy than insecticides.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Vecteurs d'importance medicale, nuisances, depredateurs des denrees et materiaux: surveillance des populations et lutte, Medically important nuisances and vectors, pests of stored products and materials: population survey and control, Vecteurs. Hôtes intermédaires, Vectors. Intermediate hosts, Arthropoda, Heteroptera, Infection, Infección, Insecta, Invertebrata, Parasitose, Parasitosis, Protozoose, Protozoal disease, Protozoosis, Reduviidae, Trypanosomiase, Trypanosomiasis, Tripanosomiasis, Fitness, Adecuación, Rhodnius prolixus, Surveillance population, Population survey, Vigilancia población, Trypanosomiase américaine, Chagas disease, Tripanosomiasis americana, Vecteur, Vector, Triatominae, biodemography, cost of reproduction, and tradeoff

Rhodnius prolixus Stal (Reduviidae: Rhodninii) is one of the most important vectors of Chagas disease. As a result of its medical importance, several life history studies have been carried out, but in general with a restricted demographical scope, without assessing the potential tradeoffs in the life history of this insect. In this study, individuals of R. prolixus were kept in two spatially different habitats and several fitness components were measured. The results show that life expectancy in adults is negatively correlated with gross fecundity, indicating a cost of reproduction. Life expectancy is shorter for males arid longer for individuals of the same sex in the more complex habitat, where the fitness is lower compared with that of the simpler habitat.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Ecologie animale, vegetale et microbienne, Animal, plant and microbial ecology, Ecologie animale et végétale, Animal and plant ecology, Autoécologie, Autoecology, Végétaux et champignons, Plants and fungi, Phytopathologie. Zoologie agricole. Protection des cultures et des forets, Phytopathology. Animal pests. Plant and forest protection, Protozoaires. Invertébrés, Protozoa. Invertebrates, Signalements, symptômes, dégâts, importance économique, surveillance des populations, Records, symptoms, damages, economic importance, population surveys, Angiospermae, Arthropoda, Dicotyledones, Heteroptera, Insecta, Invertebrata, Leguminosae, Légumineuse grain, Grain legume, Leguminosa grano, Relation animal végétal, Animal plant relation, Relación animal vegetal, Spermatophyta, Coreidae, Dégât, Damage, Estrago, Déprédateur, Pest, Plaga, Gousse, Pod, Vaina, Histopathologie, Histopathology, Histopatología, Plante hôte, Host plant, Planta huesped, Tissu végétal, Plant tissue, Tejido vegetal, and Vigna unguiculata

Histological studies were conducted on cowpea pods fed upon by the coreoid pod-sucking bugs, Anoplocnemis curvipes (Fabricius), Clavigralla tomentosicollis Stal, C. shadabi Dolling, Riptortus dentipes (Fabricius) and Mirperus jaculus (Thunberg). Various degrees of tissue and cellular disruption were apparent, especially in the brachysclereids. They were manifested in terms of plasmolysis, cell enlargement and cell wall disintegration depending on the coreoid species involved. The feeding site and its periphery had all the cells of the brachysclereids plasmolysed, with the parenchyma having broken cell walls in the case of A. curvipes. Riptortus dentipes and M. jaculus showed similar patterns of feeding activity but less extensive levels of damage. The Clavigralla spp., however, caused cell enlargement in the brachysclereids, and broken cell walls in both the brachysclereids and the parenchyma. Damage symptoms were observed in cells far away from the feeding sites of the bugs, suggesting the possibility of sucrase activity which has been reported to cause osmotic pump feeding in the Coreidae.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Phytopathologie. Zoologie agricole. Protection des cultures et des forets, Phytopathology. Animal pests. Plant and forest protection, Protozoaires. Invertébrés, Protozoa. Invertebrates, Signalements, symptômes, dégâts, importance économique, surveillance des populations, Records, symptoms, damages, economic importance, population surveys, Angiospermae, Arthropoda, Dicotyledones, Heteroptera, Insecta, Invertebrata, Leguminosae, Relation animal végétal, Animal plant relation, Relación animal vegetal, Spermatophyta, Age, Edad, Comparaison interspécifique, Interspecific comparison, Comparación interespecífica, Coreidae, Dégât, Damage, Estrago, Déprédateur, Pest, Plaga, Gousse, Pod, Vaina, Légumineuse grain, Grain legume, Leguminosa grano, Pentatomidae, Position, Posición, and Vigna unguiculata

Laboratory and screenhouse studies were carried out to assess the relationship between pod age and pod position of cowpea and damage by different pod bug species. The coreids Clavigralla tomentosicollis Stäl and Riptortus dentipes Fabricius caused significant damage to young pods of cultivated genotypes, in contrast to the coreid Anoplocnemis curvipes Fabricius and the pentatomid Aspavia armigera Fabricius which exhibited minor feeding activity. Percent seed damage declined with pod age, the critical stage for pod bug infestation being when pods were about eight days old. Clavigralla tomentosicollis and R. dentipes caused significantly higher damage to pods located within the leaf canopy, thus behaving differently from Anoplocnemis curvipes which showed a distinct preference for pods growing above the leaf canopy. The feeding activity of Aspavia armigera was not affected by the position of pods on the plant. Overall, the study suggests that cowpea genotypes with a short flowering period and pods held above the leaf canopy offer the most promise in the management of pod-sucking pests.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Ecology, Ecologie, Entomology, Entomologie, Environment, Environnement, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Phytopathologie. Zoologie agricole. Protection des cultures et des forets, Phytopathology. Animal pests. Plant and forest protection, Protozoaires. Invertébrés, Protozoa. Invertebrates, Lutte, Control, Lutte biologique, Biological control, Angiospermae, Arthropoda, Dicotyledones, Entomophage, Entomophagous, Entomófago, Heteroptera, Hymenoptera, Insecta, Invertebrata, Leguminosae, Relation hôte parasite, Host parasite relation, Relación huesped parásito, Spermatophyta, Animal auxiliaire, Beneficial animal, Animal benéfico, Coreidae, Densité population, Population density, Densidad población, Déprédateur, Pest, Plaga, Efficacité parasitaire, Parasitic efficiency, Eficacia parasitaria, Hôte, Host, Huesped, Lutte biologique, Biological control, Lucha biológica, Légumineuse grain, Grain legume, Leguminosa grano, Oophage, Oophagous, Oófago, Parasitoïde, Parasitoid, Parasitoide, Scelionidae, Taux parasitisme, Parasitism rate, Tasa parasitismo, Variation saisonnière, Seasonal variation, Variación estacional, Vigna unguiculata, Clavigralla tomentosicollis, Gryon fulviventris, and Nigeria du Nord

Field surveys were conducted on cowpea and pigeon pea in 1995 and 1996 to assess the effect of indigenous egg parasitoids on populations of Clavigralla tomentosicollis Stål in northern Nigeria. From the egg masses of C. tomentosicollis, three species of Hymenoptera belonging to three families, namel Anastatus sp. (Eupelmidae), Ooencyrtus utetheisae (Risbec) (Encyrtidae), and Gryon fulviventris (Crawford) (Scelionidae), were recorded. Among them, G. fulviventris was found to be the most abundant parasitoid. Of a total of 3,502 egg masses collected on cowpea from four geographical locations, 2,587 (73.9%) were found to contain at least one egg parasitized by G fulviventris. From 56,072 eggs discovered, it parasitized 38,935 (69.4%). Overall, 74,724 eggs were collected from the four different locations and of these 52% were parasitized by G. fulviventris. However, parasitism rates varied with time and location. At one of the study sites (Minjibir, Kano) where weekly samples were collected throughout the growing season, the discovery efficiency, exploitation efficiency, and overall percentage parasitism increased significantly from July to November. Also, the proportion of eggs parasitized was found to be inversely related to the size of the egg mass. These findings are discussed in relation to the potential contribution of biological control in the integrated pest management of this economically important pest.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Phytopathologie. Zoologie agricole. Protection des cultures et des forets, Phytopathology. Animal pests. Plant and forest protection, Protozoaires. Invertébrés, Protozoa. Invertebrates, Signalements, symptômes, dégâts, importance économique, surveillance des populations, Records, symptoms, damages, economic importance, population surveys, Angiospermae, Arthropoda, Dicotyledones, Heteroptera, Insecta, Invertebrata, Solanaceae, Spermatophyta, Densité population, Population density, Densidad población, Durée, Duration, Duración, Dégât, Damage, Estrago, Déprédateur, Pest, Plaga, Fruit, Fruto, Infestation, Infestación, Lycopersicon esculentum, Maturité, Maturity, Madurez, Pentatomidae, Plante légumière, Vegetable crop, Planta leguminosa, Chlorochroa uhleri, and Euschistus conspersus

Adult stink bugs were introduced onto caged, bush-type tomatoes to establish the amount of fruit damage resulting from different durations of infestation (up to 20 d), densities (1, 3, 5, and 10 bugs per 2 m of row), species (Euschistus conspersus Uhler and Chlorochroa uhleri (stal)) and reduced fruit abundance (75, 50, and 0% reduction). Factors that significantly influenced the percentage of tomato fruit damaged were stink bug density and reduced fruit density at constant stink bug densities. Stink bug density affected the number of damaged areas per fruit in 1 of the 2 years of the study. Stink bug species and the number of days of stink bug infestation did not affect the percentage of damaged fruit or the number of damaged areas per fruit. Implications for stink bug management in tomatoes grown in California are discussed.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Phytopathologie. Zoologie agricole. Protection des cultures et des forets, Phytopathology. Animal pests. Plant and forest protection, Protozoaires. Invertébrés, Protozoa. Invertebrates, Lutte, Control, Généralités, Generalities, Arthropoda, Composé sémiochimique, Semiochemicals, Heteroptera, Insecta, Invertebrata, Pentatomidae, Phéromone agrégation, Aggregation pheromone, Feromona agregación, aggregation pheromone, methyl (2E,6E)-farnesoate, methyl (E)-5-2,6,10-trimethyl-5,9-undecadienoate, methyl (E)-6-2,3-dihydrofarnesoate, and methyl geranate

In field trials, adult Chlorochroa uhleri (Stål) (Heteroptera: Pentatomidae) of both sexes were caught in significant numbers in cylindrical screen traps baited with gray rubber septum lures loaded with the main component of the male-produced pheromone, methyl (E)-6-2,3-dihydrofarnesoate. Addition of the two possible minor components of the pheromone, methyl (E)-5-2,6,10-trimethyl-5,9-undecadienoate and methyl (2E,6E) -farnesoate, did not affect attraction. Combining the pheromone with different concentrations of volatiles mimicking the odors of a known host plant, alfalfa (Medicago sativa L.), had no significant effect on attraction of adult bugs, whereas combining the pheromone with the pheromones of two sympatric stink bug species, Chlorochroa sayi (Stål) and Euschistus conspersus Uhler, decreased trap captures, suggesting interference between the pheromones. Small numbers of Chlorochroa ligata (Say) adults also were attracted, but numbers caught were too low to allow statistical comparisons between lure blends. In field trials with C. sayi, all three of the male-specific pheromone compounds [methyl geranate, methyl citronellate, and methyl (E) -6-2,3-dihydrofarnesoate] were required for optimal attraction. As with C. uhleri, adults of both sexes were attracted to pheromone lures in approximately equal numbers. Because of the decreased volatility (=release rate) of methyl (E)-6-2,3-dihydrofarnesoate in comparison with the other two, lower molecular weight pheromone components, lures needed to be loaded with a disproportionately high amount of methyl (E)-6-2,3-dihydrofarnesoate to obtain the best trap catch. There was no indication that the pheromone components of C. uhleri or E. conspersus interfered with the attractiveness of the C. sayi pheromone in lures containing a blend of all three pheromones.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Phytopathologie. Zoologie agricole. Protection des cultures et des forets, Phytopathology. Animal pests. Plant and forest protection, Protozoaires. Invertébrés, Protozoa. Invertebrates, Lutte, Control, Généralités, Generalities, Vecteurs d'importance medicale, nuisances, depredateurs des denrees et materiaux: surveillance des populations et lutte, Medically important nuisances and vectors, pests of stored products and materials: population survey and control, Vecteurs. Hôtes intermédaires, Vectors. Intermediate hosts, Arthropoda, Bactérie, Bacteria, Cicadomorpha, Homoptera, Insecta, Invertebrata, Mollicutes, Mycoplasmatales, Spiroplasmataceae, Cicadellidae, Dalbulus maidis, Etude expérimentale, Experimental study, Estudio experimental, Maïs, Corn, Maiz, Spiroplasma kunkelii, Vecteur, Vector, corn leafhopper, corn stunt, and spiroplasmas

Corn stunt caused by the mollicute Spiroplasma kunkelii (Whitcomb) is potentially one of the most severe diseases affecting the corn (Zea mays L.) crop in the Americas, and the leafhopper Dalbulus maidis (DeLong & Wolcott) is considered its most important vector. However, other insects seen quite frequently in corn crops might well be its vectors in Argentina. To identify any leafhoppers species other than D. maidis that can transmit S. kunkelii, transmission assays were conducted, using individuals of Exitianus obscurinervis (Stål) collected in field and reared under controlled conditions. S. kunkelii was transmitted to corn plants by E. obscurinervis. The pathogen was transmitted to seven of the 11 plants, which showed characteristic corn stunt symptoms, and the presence of the pathogen was confirmed by DAS-ELISA. The presence of S. kunkelii in the E. obscurinervis individuals used in transmission experiments was confirmed by polymerase chain reaction and electron microscopy. The current study shows the existence of a new experimental vector of S. kunkelii, the leafhopper E. obscurineruis, which acquired spiroplasmas from infected plants and inoculated it to healthy plants.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Entomology, Entomologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Phytopathologie. Zoologie agricole. Protection des cultures et des forets, Phytopathology. Animal pests. Plant and forest protection, Protozoaires. Invertébrés, Protozoa. Invertebrates, Lutte, Control, Lutte intégrée, Integrated pest control, Angiospermae, Arthropoda, Bruchidae, Coleoptera, Dicotyledones, Heteroptera, Insecta, Invertebrata, Leguminosae, Reduviidae, Spermatophyta, Callosobruchus maculatus, Canavalia ensiformis, Croissance, Growth, Crecimiento, Déprédateur, Pest, Plaga, Emergence, Emergencia, Insecticide, Insecticida, Larve, Larva, Légumineuse grain, Grain legume, Leguminosa grano, Mortalité, Mortality, Mortalidad, Mue, Molt, Muda, Origine végétale, Plant origin, Origen vegetal, Rhodnius prolixus, Toxicité, Toxicity, Toxicidad, Toxine, Toxin, and Toxina

Canatoxin is a toxic protein isolated from the jackbean, Cananvalia ensiformis. The toxin injected intraperitoneally is lethal for mice and rats; however, it is inactive if given orally. In this study, Manduca sexta (L.) (Lepidoptera), Schistocerca americana (Drury) (Orthoptera), Drosophila melanogaster (L.) (Diptera), Aedes aegypti (L.) (Diptera), Rhodnius prolixus (Stal) (Hemiptera), and Callosobruchus maculatus (F.) (Coleoptera) were fed on can-atoxin-containing diets. No effects were seen in M. sexta, S. americana, D. melanogaster, or A. aegypti. No traces of canatoxin were found in their feces, suggesting that the protein was digested completely by these insects, which characteristically have a trypsin-based digestion. In contrast, canatoxin was lethal for insects displaying cathepsin-based digestion. Thus, for C. maculatus, a diet containing 0.25% wt:wt canatoxin caused complete inhibition of larval growth. When R. prolixus were fed on canatoxin, 2 effects were seen: impairment of water excretion and increased lethality 48-96 h after feeding. The lethal effect of canatoxin in R. prolixus was blocked partially or completely when the digestion of the toxin by R. prolixus midgut enzymes was impaired. The data showed that canatoxin is highly toxic when ingested by some species of insects but not affecting others, probably in correlation with the characteristics of the digestive process of the insect.