934 resultados para insect succession


Relevância:

20.00% 20.00%

Publicador:

Resumo:

We outline a philosophical approach to Grand Challenge projects, with particular reference to our experience in our food security project involving the protection of stored grain from insect attack in two countries on different continents. A key consideration throughout has been the management of resistance in these pests to the valuable fumigant phosphine. Emphasis is given to the chain of research issues that required solution and the assembly of a well-integrated team, overlapping in skills for effective communication, in each country to solve the problems identified along that chain. A crucial aspect to maintaining direction is the inclusion of key end users in all deliberations, as well as the establishment and maintenance of effective outlets for the dissemination of practical recommendations. We finish with a summary of our achievements with respect to our approach to this food security Grand Challenge.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Sulfuryl fluoride (SF), an effective structural fumigant, is registered recently as Profume™ for controlling insect pests of stored grains and processed commodities. Information on its effectiveness in disinfestation of bulk grain, however, is limited. The ongoing problem with the strong level of resistance to phosphine has been addressed recently through deployment of SF as a ‘resistance breaker’ in bulk storages in Australia. This paper discusses important results on the efficacy of SF against key phosphine- resistant insect pests, lesser grain borer, Rhyzopertha dominca, red flour beetle, Tribolium castaneum, rice weevil, Sitophilus oryzae and the rusty grain beetle, Cryptolestes ferrugineus. We have established CT (g-hm3) profiles for SF against these insect pests at two temperature regimes 25 and 30°C, that showed that both temperature and exposure period (t) has significant influence on the effectiveness of SF than the concentration. Over a seven days fumigation period, CTs of 800 and 400 g-hm3 achieved complete control of all the target pests, including the most strongly phosphine - resistant species, C. ferrugineus at 25 and 30°C, respectively. Results from four industry scale field trials involving currently registered rate of SF (1500 g-hm3) over 2–14 d exposure period, confirmed its effectiveness in achieving complete control of the target pest species. The assessment of postfumigation grain samples across all the test storages indicated that the reinfestation occurs after three months. Monitoring resistance to phosphine in C. ferrugineus over a six year period (2009–2015), showed a significant reduction in resistant populations after the introduction of SF into the fumigation strategy at problematic storage sites. Overall our research concludes that SF is a good candidate to be used as a ‘resistance breaker’ where phosphine resistance is prevalent.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In response to numerous reports of failures to control insect pests of stored products with phosphine in Vietnam, a national survey for resistance to this key fumigant was undertaken in 2009–2011. Data from a more limited survey undertaken by the authors in 2002 in northern Vietnam are also presented. Samples collected in the 2002 survey (Sitophilus oryzae, n=8; Tribolium castaneum, n=8) were tested using a full dose- response assay, while for the 2009–11 survey, F1 generations were tested for resistance with two discriminating dosages of phosphine to detect frequency of weak and strong resistance phenotypes. Compared with a susceptible reference strain, in 2002, resistance to phosphine was indicated in six T. castaneum samples but only two of S. oryzae. Resistance factor, however, did not exceed 2.8-fold in T. castaneum and 1.7 in S. oryzae indicating relatively low frequency and weak expression of resistance. In 2009–11 survey, 176 samples were collected from a range of food and feed storages along the supply chain and from all major regions of Vietnam (125 sites). Rhyzopertha dominica and S. oryzae were the most common species found infesting stored commodities. Resistance was detected at high frequency in all the species. Weak and strong resistance phenotype frequencies were, respectively: Cryptolestes ferrugineus (37 and 58%, n=19), R. dominica (1.5 and 97%, n=65), S. oryzae (34 and 59%, n=82) and T. castaneum (70 and 30%, n=10). Strong resistance phenotype was detected in all the major regions and all parts of the supply chain but frequency was the highest in central storages and animal feed establishments. The increase in frequency and strength of resistance to phosphine in the eight years between the two surveys has been rapid and dramatic. The survey demonstrates the threat of resistance to grain protection in Vietnam and highlights the need for training of fumigators, and the development and adoption of phosphine resistance management tactics nationally.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Ten years ago, cohabitants in Scotland had no statutory rights in respect of their deceased partner’s estate. Section 29 of the Family Law (Scotland) Act 2006 gave cohabitants the right to apply to the court for discretionary provision from their deceased partner’s intestate estate. This thesis examines the process of making such an application and the way that the provisions have been applied in practice. The juxtaposition of the Family Law (Scotland) Act 2006 and the existing rules for intestate succession in the Succession (Scotland) Act 1964 is considered, with particular focus on the subordination of cohabitants’ rights to the succession rights of a surviving spouse, and the negative impact that this may have on children. It is concluded that the current succession framework is incapable of protecting cohabitants and children in reconstituted families. Potential measures are considered to displace the traditional primacy of marital succession rights, and provide a fair and flexible system of succession law that is capable of dealing with complex family structures.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

International audience

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A 67-year-old woman developed severe edema of her right hand and forearm, for which she was treated with antibiotics, without benefit. The echography excluded a venous thrombosis. Subsequently, she referred a wasp sting before the development of the edema. Specific Hymenoptera venom immunoglobulin E (IgE) was found to be positive for paper wasp and yellow jacket. A large local reaction (LLR) was diagnosed due to the hymenoptera sting. Self-injectable epinephrine was prescribed for possible, though unlikely, systemic reactions following hymenoptera stings.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Les écosystèmes dunaires remplissent plusieurs fonctions écologiques essentielles comme celle de protéger le littoral grâce à leur capacité d’amortissement face aux vents et vagues des tempêtes. Les dunes jouent aussi un rôle dans la filtration de l’eau, la recharge de la nappe phréatique, le maintien de la biodiversité, en plus de présenter un attrait culturel, récréatif et touristique. Les milieux dunaires sont très dynamiques et incluent plusieurs stades de succession végétale, passant de la plage de sable nu à la dune bordière stabilisée par l’ammophile à ligule courte, laquelle permet aussi l’établissement d’autres herbacées, d’arbustes et, éventuellement, d’arbres. Or, la survie de ces végétaux est intimement liée aux microorganismes du sol. Les champignons du sol interagissent intimement avec les racines des plantes, modifient la structure des sols, et contribuent à la décomposition de la matière organique et à la disponibilité des nutriments. Ils sont donc des acteurs clés de l’écologie des sols et contribuent à la stabilisation des dunes. Malgré cela, la diversité et la structure des communautés fongiques, ainsi que les mécanismes influençant leur dynamique écologique, demeurent relativement méconnus. Le travail présenté dans cette thèse explore la diversité des communautés fongiques à travers le gradient de succession et de conditions édaphiques d’un écosystème dunaire côtier afin d’améliorer la compréhension de la dynamique des sols en milieux dunaires. Une vaste collecte de données sur le terrain a été réalisée sur une plaine de dunes reliques se trouvant aux Îles de la Madeleine, Qc. J’ai échantillonné plus de 80 sites répartis sur l’ensemble de ce système dunaire et caractérisé les champignons du sol grâce au séquençage à haut débit. Dans un premier temps, j’ai dressé un portait d’ensemble des communautés fongiques du sol à travers les différentes zones des dunes. En plus d’une description taxonomique, les modes de vie fongiques ont été prédits afin de mieux comprendre comment les variations au niveau des communautés de champignons du sol peuvent se traduire en changements fonctionnels. J’ai observé un niveau de diversité fongique élevé (plus de 3400 unités taxonomiques opérationnelles au total) et des communautés taxonomiquement et fonctionnellement distinctes à travers un gradient de succession et de conditions édaphiques. Ces résultats ont aussi indiqué que toutes les zones des dunes, incluant la zone pionière, supportent des communautés fongiques diversifiées. Ensuite, le lien entre les communautés végétales et fongiques a été étudié à travers l’ensemble de la séquence dunaire. Ces résultats ont montré une augmentation claire de la richesse spécifique végétale, ainsi qu’une augmentation de la diversité des stratégies d’acquisition de nutriments (traits souterrains lié à la nutrition des plantes, soit mycorhizien à arbuscule, ectomycorhizien, mycorhizien éricoide, fixateur d’azote ou non spécialisé). J’ai aussi pu établir une forte corrélation entre les champignons du sol et la végétation, qui semblent tous deux réagir de façon similaire aux conditions physicochimiques du sol. Le pH du sol influençait fortement les communautés végétales et fongiques. Le lien observé entre les communautés végétales et fongiques met l’emphase sur l’importance des interactions biotiques positives au fil de la succession dans les environnements pauvres en nutriments. Finalement, j’ai comparé les communautés de champignons ectomycorhiziens associées aux principales espèces arborescentes dans les forêts dunaires. J’ai observé une richesse importante, avec un total de 200 unités taxonomiques opérationnelles ectomycorhiziennes, appartenant principalement aux Agaricomycètes. Une analyse de réseaux n’a pas permis de détecter de modules (c'est-à-dire des sous-groupes d’espèces en interaction), ce qui indique un faible niveau de spécificité des associations ectomycorhiziennes. De plus, je n’ai pas observé de différences en termes de richesse ou de structure des communautés entre les quatre espèces hôtes. En conclusion, j’ai pu observer à travers la succession dunaire des communautés diversifiées et des structures distinctes selon la zone de la dune, tant chez les champignons que chez les plantes. La succession semble toutefois moins marquée au niveau des communautés fongiques, par rapport aux patrons observés chez les plantes. Ces résultats ont alimenté une réflexion sur le potentiel et les perspectives, mais aussi sur les limitations des approches reposant sur le séquençage à haut-débit en écologie microbienne.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Microorganisms in the plant rhizosphere, the zone under the influence of roots, and phyllosphere, the aboveground plant habitat, exert a strong influence on plant growth, health, and protection. Tomatoes and cucumbers are important players in produce safety, and the microbial life on their surfaces may contribute to their fitness as hosts for foodborne pathogens such as Salmonella enterica and Listeria monocytogenes. External factors such as agricultural inputs and environmental conditions likely also play a major role. However, the relative contributions of the various factors at play concerning the plant surface microbiome remain obscure, although this knowledge could be applied to crop protection from plant and human pathogens. Recent advances in genomic technology have made investigations into the diversity and structure of microbial communities possible in many systems and at multiple scales. Using Illumina sequencing to profile particular regions of the 16S rRNA gene, this study investigates the influences of climate and crop management practices on the field-grown tomato and cucumber microbiome. The first research chapter (Chapter 3) involved application of 4 different soil amendments to a tomato field and profiling of harvest-time phyllosphere and rhizosphere microbial communities. Factors such as water activity, soil texture, and field location influenced microbial community structure more than soil amendment use, indicating that field conditions may exert more influence on the tomato microbiome than certain agricultural inputs. In Chapter 4, the impact of rain on tomato and cucumber-associated microbial community structures was evaluated. Shifts in bacterial community composition and structure were recorded immediately following rain events, an effect which was partially reversed after 4 days and was strongest on cucumber fruit surfaces. Chapter 5 focused on the contribution of insect visitors to the tomato microbiota, finding that insects introduced diverse bacterial taxa to the blossom and green tomato fruit microbiome. This study advances our understanding of the factors that influence the microbiomes of tomato and cucumber. Farms are complex environments, and untangling the interactions between farming practices, the environment, and microbial diversity will help us develop a comprehensive understanding of how microbial life, including foodborne pathogens, may be influenced by agricultural conditions.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Fungal fruit rots and insect pests are among the most important problems negatively affecting the yield and quality of mid-Atlantic wine. In pathogenicity trials of fungi recovered from diseased Chardonnay and Vidal blanc grapes, Alternaria alternata, Pestalotiopsis telopeae, and Aspergillus japonicus were found to be unreported fruit rot pathogens in the region. Additionally, P. telopeae and A. japonicus had comparable virulence to the region’s common fruit rot pathogens. Furthermore, a timed-exclusion field study was implemented to evaluate vineyard insect-fruit rot relationships. It was found that clusters exposed to early-season insect communities that included Paralobesia viteana had a significantly greater incidence of sour rot than clusters protected from insects all season. These results were contrary to the current assumption that fall insects are the primary drivers of sour rot in the region. This research provides diagnostic tools and information to develop management-strategies against fungal and insect pests for mid-Atlantic grape growers.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

While succession intentions have received increasing scholarly attention in recent years, there is a lack of knowledge about country-level antecedents and differences. Our paper aims to close this gap by investigating succession intentions of 6,360 students with family business background from 26 countries. More specifically, we blend theory of planned behavior with institutional theory and find that institutional variables such as individualism, uncertainty avoidance, and the level of corruption explain the formation of succession intentions over and above traditional theory of planned behavior elements. In addition, we reveal a U-shaped relationship between a nation's level of economic development and the strength of succession intentions. This indicates the existence of two types of succession intentions: necessity and opportunity succession. These findings add valuable insights to literature on family businesses, succession, theory of planned behavior, and practice.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

2016