The role of <Emphasis Type="Italic">Euwallacea</Emphasis> nr. <Emphasis Type="Italic">fornicatus</Emphasis> (Coleoptera: Scolytinae) in the wilt syndrome of avocado trees in Israel     

Zvi Mendel  Alex Protasov  Yonatan Maoz  Marcel Maymon  Golan Miller  Meirav Elazar  Stanley Freeman 《Phytoparasitica》2017,45(3):341-359

The polyphagous shot hole borer (PSHB), Euwallacea nr. fornicatus (Coleoptera; Scolytinae) has become a serious threat to the avocado industry and several shade tree species in Israel. Branch wilting and tree mortality is the outcome of PSHB galleries. Understanding the relationship between avocado trees and the PSHB is required for considering management strategies. In Israel, 52 tree species from 26 botanical families were attacked by the PSHB, but only 12 species were suitable for beetle reproduction. All examined avocado cultivars were attacked, but ‘Hass’ most severely. Large and medium diameter avocado branches were more resistant to PSHB, compared to thin branches. Effectively, gallery density increased as branch diameter decreased. Concomitantly, in large and medium diameter branches, extensive sugar exudation occurred and beetle attack rarely progressed to the formation of natal galleries, whereas minimal sugar exudation was observed in thin branches. This was more evident in those that were weakened by repeated attacks followed by successful beetle colonization. PSHB prefers and successfully colonized branches that had been previously attacked by its conspecifics, and reproduction was much higher in these branches, as opposed to initial attacks. Lesion frequencies increased from late spring (April) until late summer (September). Avocado branches at the early stages of beetle colonization may be identified by sugar exudation at the base of the thin branches. The main approach for reducing damage caused by the PSHB is sanitation, achieved by the removal of colonized branches and intact infested pruned slash.  相似文献   

Development of a method for detection of latent European fruit tree canker (<Emphasis Type="Italic">Neonectria ditissima</Emphasis>) infections in apple and pear nurseries     

Marcel Wenneker  Peter F. de Jong  Nina N. Joosten  Paul W. Goedhart  Bart P. H. J. Thomma 《European journal of plant pathology / European Foundation for Plant Pathology》2017,148(3):631-635

Fruit tree canker caused by Neonectria ditissima is a serious problem in apple-producing regions with moderate temperatures and high rainfall throughout the year; especially in northwestern Europe, Chile, and New Zealand. Control measures are applied to protect primary infection sites, mainly leaf scars, from invasion by external inoculum. However, latent infections may occur when young apple trees are infected symptomlessly during propagation. This study aimed to develop a method for detection of latent fruit tree canker infections. Inoculations with conidiospore suspensions of N. ditissima were carried out in tree nurseries on the main stems of two-year-old trees of three apple cultivars and one pear cultivar. The inoculations were carried out during the natural abscission period in the autumn. No visible lesion or canker formations were present at the time when the inoculated trees were uprooted. It appeared that the infections may remain latent during the period from infection to uprooting (2 months) and during the subsequent 4 months of cold storage of the trees. Nevertheless, symptoms were generally induced within 8 weeks after transfer of infecting planting material from the nursery field into a climate chamber with high temperature and high relative humidity. The methodology presented is developed to detect latent infections of N. ditissima in nursery trees, prior to planting in the orchards, and it may contribute in reducing the problem with European fruit tree canker in commercial production.  相似文献   

Quantitative trait loci associated with trichomes in the <Emphasis Type="Italic">Solanum galapagense</Emphasis> accession LA1401     

Marcela Carvalho Andrade  Alex Antônio da Silva  Regis de Castro Carvalho  Juliana de Andrade Santiago  Alisson Marcel Souza de Oliveira  David Merrill Francis  Wilson Roberto Maluf 《Genetic Resources and Crop Evolution》2018,65(6):1671-1685

Pest resistance in Solanum galapagense has been associated with the presence of type IV glandular trichomes and allelochemicals. Knowledge of the genetic factors involved in determining the presence and type of trichomes may assist in the process of gene introgression for development of pest resistant tomato cultivars. In this study, we sought to identify QTLs associated with the presence of type IV trichomes in an F₂ population derived from the interspecific cross of Solanum lycopersicum TOM-684?×?S. galapagense accession LA1401. Two QTLs contributing to type IV trichome occurrence and density were detected, one major QTL (gal.IV-2), responsible for 35.22% of phenotypic variation, was located on chromosome 2. The other QTL (gal.IV-3) was located on chromosome 3, and explained 23.35% of the phenotypic variation in the F₂ population. These QTLs were responsible for 26.44 and 3.37% of the variation observed in a progeny derived from a backcross to TOM-684. The same QTLs were also associated with type II?+?III non-glandular trichomes, whose densities were negatively correlated to those of type IV trichomes, suggesting that the loci found may have pleiotropic effects for high type IV/low type II?+?III trichome densities. Our results indicate that the inheritance for type IV trichomes can be explained by a few genetic factors affecting the presence of a gland and the density of trichomes. These results further suggest a revision to trichome classification used for tomato may be appropriate.  相似文献   

Long-term growth response of black spruce advance regeneration (layers), natural seedlings and planted seedlings to scarification: 25th year update     

Marcel Prévost  Daniel Dumais 《Scandinavian Journal of Forest Research》2018,33(6):583-593

Careful logging around advance growth and tree planting following site preparation or not (fill planting) have been widely used to regenerate black spruce (Picea mariana) stands in the boreal forest of Canada. An experiment was established in 1990 to compare these regeneration modes and natural seeding over a 25-year period following two types of scarification (cone- or disk-trenching) that were applied at two intensities (single- or double-pass). Without scarification, the three types of regeneration had slow height growth during the first 10 years (3.4–5.8?cm/year). Thereafter, planted seedlings (6.1–9.8?cm/year) and pre-established layers (5.8–8.5?cm/year) had 2–3 times higher growth than natural seedlings (2.6–3.1?cm/year). Scarification improved height growth of the three types of regeneration, but planted seedlings responded much earlier, and more strongly over the 25 years (+9.4?cm/year) than layers (+2.8?cm/year) and natural seedlings (+2.7?cm/year). A shift in the proportion of layers and natural seedlings was observed following treatment. Long-term monitoring revealed that double-pass scarification was beneficial to layer growth from years 15 to 20, while no positive effect was observed on natural or planted seedlings. Our results suggest that decades may be required for natural regeneration to respond to scarification in cold soils of the boreal forest.  相似文献   

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   

Precipitation-dependent source–sink dynamics in a spatially-structured population of an outbreaking caterpillar     

Grof-Tisza  Patrick  Pepi  Adam  Holyoak  Marcel  Karban  Richard 《Landscape Ecology》2019,34(5):1131-1143

Context

Patch-based population models predominately focus on factors that affect regional processes namely, patch size and connectivity, as the primary drivers explaining patch occupancy. This trend persists despite the recognition that patch quality can strongly influence population demography at the local scale. The quality of patches is often temporally variable and influenced by abiotic conditions. However, few studies have explicitly investigated how climatic variables influence the spatial and temporal dynamics of spatially-structured populations either directly or indirectly through changes in patch quality.

Objectives

Using a 10-year census of a spatially-structured population of an outbreaking caterpillar, we determined the relative importance of patch quality (determined demographically), connectivity, precipitation, and their interactive effects on patch abundance, occupancy, colonization, and extinction.

Methods

We generated a series of statistical models and performed comparisons using Akaike’s information criterion. We subsequently used likelihood ratio tests to determine the influence of each parameter on model fit.

Results

Patch quality and precipitation were the strongest predictors of the observed dynamics. We found that the dynamics of the spatially-structured population of Arctia virginalis were strongly influenced by precipitation: all patches had a higher probability of occupancy, contained higher abundances of caterpillars, and experienced fewer extinctions following wet winters compared to years following droughts.

Conclusion

These findings suggest that precipitation may act to influence the strength of heterogeneity of patch quality. This work demonstrates that patch-based models that do not include local and climatic factors may produce poor predictions under future climatic regimes.

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A non‐paradoxical dose response to 17α‐methyltestosterone by Nile tilapia Oreochromis niloticus (L.): effects on the sex ratio,growth and gonadal development     

Ronald P Phelps  Marcel Okoko 《Aquaculture Research》2011,42(4):549-558

Commercial tilapia production is dependent on monosex culture, commonly obtained through the inclusion of an androgen in the diet for a brief period soon after hatch. To determine a minimum effective dose and identify the problems associated with over‐dosing, Nile tilapia Oreochromis niloticus fry were fed diets containing methyltestosterone (MT) at rates up to 1200 mg kg^?1 of diet for 28 days. The minimum effective dose for ≥95% males was 14 mg MT kg^?1 diet. Percent phenotypic males increased as the rate increased from 3.75 (80%) to 30 mg kg^?1 MT (99%). Methyltestosterone given at rates of 120 mg kg^?1 or more reduced efficacy but did not result in a reduced frequency of males relative to that of non‐treated fish. The term ‘paradoxical feminization’ does not adequately describe the observed sex ratios, where no fish were feminized but the efficacy of MT at high doses to masculinize females was reduced. At 1200 mg MT kg^?1, the frequency of females (48 ± 1%) was not different from that in the non‐treated population. The mechanism for the reduced efficacy is not clear and is not adequately explained as an aromatization of androgen to oestrogen response.  相似文献   

Transcriptional expression of immune system genes in Litopenaeus vannamei during ontogenetic development          下载免费PDF全文

Teresa Gollas‐Galvan  Miguel Cabanillas‐Gámez  Jorge Hernández‐López  Daniel Coronado‐Molina  Marcel Martínez‐Porchas 《Aquaculture Research》2017,48(3):1110-1118

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