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191.

We provide an overview of both traditional and innovative control tools for management of three Xylosandrus ambrosia beetles (Coleoptera: Curculionidae: Scolytinae), invasive species with a history of damage in forests, nurseries, orchards and urban areas. Xylosandrus compactus, X. crassiusculus and X. germanus are native to Asia, and currently established in several countries around the globe. Adult females bore galleries into the plant xylem inoculating mutualistic ambrosia fungi that serve as food source for the developing progeny. Tunneling activity results in chewed wood extrusion from entry holes, sap outflow, foliage wilting followed by canopy dieback, and branch and trunk necrosis. Maintaining plant health by reducing physiological stress is the first recommendation for long-term control. Baited traps, ethanol-treated bolts, trap logs and trap trees of selected species can be used to monitor Xylosandrus species. Conventional pest control methods are mostly ineffective against Xylosandrus beetles because of the pests’ broad host range and rapid spread. Due to challenges with conventional control, more innovative control approaches are being tested, such as the optimization of the push–pull strategy based on specific attractant and repellent combinations, or the use of insecticide-treated netting. Biological control based on the release of entomopathogenic and mycoparasitic fungi, as well as the use of antagonistic bacteria, has yielded promising results. However, these technologies still require validation in real field conditions. Overall, we suggest that management efforts should primarily focus on reducing plant stress and potentially be combined with a multi-faceted approach for controlling Xylosandrus damage.

  相似文献   
192.
Bacterial nutrition of great scallop, Pecten moximus, larvae was investigated using the radioactive tracer technique. The bacterial labelling was studied initially to obtain a high and stable specific radioactivity (14C) of bacterial cells. A higher bacterial specific 14C activity was obtained when the tracer (amino acid) was introduced in the culture medium at the beginning of the exponential growth phase. After a 12 h labelling period in a rich nutritive medium, the bacteria were depurated in seawater for 5 h (chase) to prevent further 14C excretion and then added to larval rearing vessels. The larval labelling was followed for 12 h and then larvae were placed in new vessels without radioactive bacteria. The depuration of larvae was followed for 3 days. Data obtained on ingestion and assimilation efficiency show that bivalve larvae are able to ingest and digest bacteria.  相似文献   
193.
The co‐culture of juvenile sea cucumber Holothuria scabra (Jaeger), or ‘sandfish’, with juvenile blue shrimp Litopenaeus stylirostris (Stimpson) was tested by growing groups in co‐culture and monoculture for 3 weeks in tanks with enriched sand substratum. Feed was supplied on trays, accessible only to shrimp. Survival of shrimp and sandfish was high in all treatments (73–100%). Growth of shrimp did not differ between monoculture and co‐culture, but sandfish grew significantly slower in co‐culture (P=0.03), although their sand burying and surface foraging were apparently unaffected by shrimp (P=0.76). However, shrimp increased the levels of total ammonia‐N in tanks, which related inversely with sandfish growth (P=0.04). Conversely, sandfish did not appear to lower the water quality for shrimp culture. While sandfish bioturbate sediments and eat organic deposits, the juveniles did not significantly reduce the organic content of sand in tanks. Co‐culturing juveniles of the two species in earthen ponds appears feasible, with no detriment to shrimp production, presenting a cost‐effective method for growing sandfish to larger sizes for restocking. These findings underpin further studies to test the viability of commercial co‐culture of sandfish with blue shrimp at later stages in the production cycle of shrimp.  相似文献   
194.
The silviculture of hybrid poplars and other fast-growing tree species is a promising solution to reduce the pressure on natural forests while maintaining wood supplies to industries. However, hybrid poplars are very sensitive to competing vegetation and to inadequate soil conditions and fertility. Possible management tools include mechanical site preparation (MSP), vegetation control (VC), and fertilization. Experimental plantations of hybrid poplars (one clone, Populus balsamea × Populus maximowiczii) were established at eight formerly forested sites on acidic soil in the southern boreal forest of Quebec, Canada. The objective was to test the response of hybrid poplars to the interaction of several silvicultural tools, which has been rarely done. Four MSP treatments (in decreasing order of intensity: mounding, harrowing, heavy disk trenching, light disk trenching) and a control (unprepared) were all combined with four different frequencies of plant competition control by brushing (from never up to once a year). Fertilization with N or N + P was also tested in three selected MSP treatments. After five years, hybrid poplar tree growth among MSP treatments increased in the following order: unprepared < light disk trenching < heavy disk trenching < harrowing < mounding. MSP was also essential in favouring early tree survival, as illustrated by mortality rates of over 20% in unprepared plots and below 5% in all other MSP treatments. The effect of competition control on hybrid poplar growth was greatest in the less intensive MSP treatments, where competing vegetation was the most abundant. On the contrary, fertilization effect was significant only in the most intensive MSP (mounding). Moreover, neither fertilization nor VC could compensate for inadequate soil preparation. Of all the silvicultural treatments tested, mounding provided the best tree growth despite a nitrogen and carbon impoverished surface soil.  相似文献   
195.
Since 2004 the oriental fruit fly, Bactrocera dorsalis (Hendel) has become widespread and economically important in Wuhan, Hubei Province, central China. In this article, the population dynamics of B. dorsalis were monitored using methyl eugenol-baited traps during 2008–2009 in Wuhan. Adults were captured from early July to the end of December in a citrus orchard and peaked in October and early November. Adult population peak coincided with the ripeness period of sweet oranges in October. Infestation with B. dorsalis was more serious in 2009 than in 2008. Field surveys of host plants for this fly species combined with rearing experiments indicated that pear was the first host plant infested by B. dorsalis. We recorded the following host shift pattern: pear (Pyrus communis L.), jujube (Zizyphus jujuba L.), persimmon (Diospyros kaki L.), and sweet orange (Citrus unshiu Marcor). Our findings suggest that B. dorsalis completes four to five generations per year in this area and most serious damage occurred in the 4th generation in the citrus orchards. The availability of preferred host fruits and the low winter temperature are key factors influencing population fluctuations. Overwintering potential experiments of adults, larvae, and pupae were also carried out in the field. Results suggest that a small proportion of pupae were able to survive winter in Wuhan and emerged successfully the following year. Practical and theoretical implications of the results regarding the invasion potential and management strategy of B. dorsalis in Hubei Province are discussed.  相似文献   
196.
Matrix-Assisted Laser Desorption/Ionisation (MALDI) mass spectrometry imaging (MSI) uses the power of high mass resolution time of flight (ToF) mass spectrometry coupled to the raster of lasers shots across the cut surface of tissues to provide new insights into the spatial distribution of biomolecules within biological tissues. The history of this technique in animals and plants is considered and the potential for analysis of proteins by this technique in plants is discussed. Protein biomarker identification from MALDI-MSI is a challenge and a number of different approaches to address this bottleneck are discussed. The technical considerations needed for MALDI-MSI are reviewed and these are presented alongside examples from our own work and a protocol for MALDI-MSI of proteins in plant samples.  相似文献   
197.
BACKGROUND: Termites are degradation agents that inflict severe damage on wood. Some long‐lasting Amazonian trees can resist these insects by producing toxic secondary metabolites. These metabolites could potentially replace synthetic termiticidal products which are becoming more restricted to use. RESULTS: Sextonia rubra is resistant to termite‐induced degradation. It has been demonstrated that this species naturally produces an ethyl‐acetate‐soluble termiticidal metabolite, rubrynolide, to protect its wood. Assays in the presence of tropical and invasive termites established that both rubrynolide and crude ethyl acetate extract from S. rubra wood can be used as a treatment for the protection of sensitive woods against termites. CONCLUSION: Rubrynolide and S. rubra extract are promising candidates for the replacement of synthetic termiticides. Copyright © 2011 Society of Chemical Industry  相似文献   
198.
Decline induced by Chalara fraxinea is an emerging disease that severely affects ash stands in Europe. The disease appears to have an invasive spread from East to West of Europe in the last decade. The teleomorphic stage, Hymenoscyphus pseudoalbidus, that occurs as apothecia on ash rachis in the litter was recently described. The origin of ash decline remains unclear as a cryptic species, H. albidus, a long-established fungus in Europe, could be present in the same niche, and as in Switzerland, H. pseudoalbidus was shown to have been present long before the recent epidemic outbreak. In France, the emerging disease is very recent and clearly restrained to Northeastern France. We thus collected isolates from infected hosts and from apothecia/ash rachis both inside and outside the infected area in France in order to compare them on the basis of pathogenicity towards ash seedlings and sequences of the ITS regions and of three single-copy genes. We showed that two population types exhibiting about 2% base pair polymorphism in the sequences analysed were present in Northern France. The first type, corresponding to H. pseudoalbidus, was present on rachis and infected hosts only in Northeastern France and showed strong pathogenicity towards ash seedlings in inoculation tests. By contrast, the second type, which corresponds to H. albidus, was present throughout Northern France and showed no pathogenicity towards ash seedlings. Our study confirms the results of Queloz et al. (2010) who presented molecular evidences for the existence of two cryptic species, H. albidus and H. pseudoalbidus. The results strongly suggest that Chalara fraxinea/H. pseudoalbidus is a recent invader in France.  相似文献   
199.
A commercial glucose oxidase (GOX) from Aspergillus niger was partially characterized. The enzyme exhibited a two-step transfer mechanism, and the kinetic constants toward glucose and oxygen were determined. Under conditions similar to dough making (glucose concentration and pH), GOX does not exhibit maximum activity. A hexose oxidase (HOX) from Chondrus crispus was partially characterized as well. The HOX activity is not far from the optimum in the kneading conditions (pH and glucose concentration). A peroxidase (POD) purified from wheat germ was used to oxidize ferulic acid in the presence of GOX or HOX. Hydrogen peroxide produced during the glucose oxidation activates the wheat germ POD. Ferulic acid oxidation in solutions containing different ratios of POD + GOX or HOX + POD was followed by UV spectrophotometry. For the same dosage, the HOX-POD system is the most efficient for peroxidase activation. Using absorbance data and kinetic constants of GOX and POD, a mathematical model describing the release or consumption of the different reactants (hydrogen peroxide, oxygen, and ferulic acid) in the medium was developed, and experimental data correlated well with calculated values. The results obtained will be applied to investigate the effect of GOX and HOX activities on the rheological properties of dough.  相似文献   
200.
Two isoforms of catalase, CAT-1 and CAT-2, were purified from wheat germ after extraction, ammonium sulfate precipitations, hydrophobic chromatography, and two ionic-exchange chromatographies. The global yields and the purification factors were close to 3% and 50 for CAT-1 and close to 6% and 100 for CAT-2. Both isoforms exhibit an optimum activity at pH 7. When pH was decreased from 7 to 5.6, CAT-1 showed a decreasing affinity for its substrate, whereas the opposite was found for CAT-2. Both isoforms were irreversibly denaturated when exposed to acidic pH, CAT-1 being more sensitive than CAT-2. Conversely, CAT-2 appeared to be more sensitive to inhibitors. The rate as well as the extent of denaturation during incubation with 3-amino-1,2,4-triazole (AT) were higher with CAT-2 than with CAT-1. Guaiacol is a competitive inhibitor more potent with respect to CAT-2. The difference in affinity for hydrogen peroxide as well as the poor stability of CAT-1 in acidic medium suggests that this isoform could be less effective during dough mixing.  相似文献   
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