Modelling jay (Garrulus glandarius) abundance and distribution for oak regeneration assessment in Mediterranean landscapes

Because natural regeneration of oak is strongly dependent on jay abundance and distribution, we need to understand the determinants of jay abundance and occurrence as a first step to assess oak regeneration. In this paper we modelled the jay population distribution and abundance in a Mediterranean landscape mosaic of the eastern Iberian Peninsula (Valencia, east Spain). The methodology was based on assessing landscape attributes (habitat composition and configuration variables) on seven 9-km² sites and registering jay fledgling locations. Using a stepwise regression model we determined the variables that best explained the jay density. The probability of occurrence of jay nests within each site was assessed by comparing the landscape attributes of jay and non-jay areas within each site. Results were validated by predicting each site on the basis of data from the remaining six sites and then calculating the deviation between the predicted and the observed values in the field. The results suggest that jay density correlates positively with forest cover and landscape heterogeneity variables, and negatively with shrubland cover. Validation of the results showed that the model is reasonably effective in predicting both jay abundance and distribution at the extent and resolution used.     

应用重金属和有机污染物对人体健康的风险评价理论反推牡蛎安全消费量

为了提供牡蛎食用安全性参考信息,文章根据有毒化学物质的人体健康风险评估计算式,提出了牡蛎适宜消费量推算方法;对2007年春季在南海北部沿岸23个海湾采集的近江牡蛎（Crassostrea rivularis）样品,用气相色谱法测定了其中有机氯农药、多氯联苯的含量,用原子吸收分光光度法和原子荧光分光光度法测定了其中重金属的含量,推算了近江牡蛎的适宜消费量。结果能清晰地显示牡蛎采集海域、有毒化学物质种类对应的近江牡蛎软组织日均适宜消费量。     

珠海养殖池塘沉积物中BHC和DDT残留与风险分析

测定了珠海水产养殖池塘沉积物中六六六(BHC)和滴滴涕(DDT)残留量。结果显示,ΣBHC、ΣDDT残留量(湿重)分别为0.36～1.67、0.95～2.59μg·kg~(-1),平均分别为0.91、1.81μg·kg~(-1),明显低于一些江河、湖泊、海湾沉积物中的含量,符合我国无公害水产品产地沉积环境质量标准。γ-BHC/ΣBHC 比值为0～21.6%,(DDE DDD)/ΣDDT 比值为61.1%～76.7%,表明珠海池塘养殖环境中的 BHC 日趋减少,推测残留的DDT 大部分已降解为 DDE 和 DDD,近年没有 BHC 和 DDT 输入。BHC 和 DDT 含量低于 ERL 值,表明 BHC 和DDT 残留对珠海池塘养殖基地造成的生态风险极低。     

Spatial and temporal behavior of coffee rust in C. canephora and its effects on crop yield

European Journal of Plant Pathology - Coffee rust has been one of the main factors responsible for reducing crop yield. The management of this disease corresponds to one of the main costs in the...     

Peptide derivatives of dermaseptin S4 in fresh bovine semen for bacterial contamination control: Physicochemical and structural characterization,antibacterial potency,and effects on red blood and sperm cells

The objectives of this study were to examine the physicochemical and structural properties of peptide derivatives of dermaseptin S4, investigate their detrimental effects on red blood and sperm cells and ascertain their antibacterial potency to control bacterial contaminants in fresh bovine semen. The dermaseptin S4 peptide derivatives used in this study were K4S4, S4(5–28), S4(5–28)a, K20S4(5–28), K4S4(1–16)a, K4S4(1–15)a and K4S4(1–15). Peptides K4S4, S4(5–28)a, K20S4(5–28), K4S4(1–15)a and K4S4(1–16)a, with a higher positive charge, were the most potent against the bacterial strains tested, with the lowest minimum inhibitory concentration (MIC), whereas S4(5–28) and K4S4(1–15), with a lower positive charge, showed the highest MIC (p < .01). Haemolysis percentage depended on peptide concentration (p < .01). The K4S4 was the most powerful haemolytic peptide, showing the highest haemolysis percentage at all peptide concentrations (p < .01). In contrast, S4(5–28), S4(5–28)a, K20S4(5–28) and K4S4(1–15) were not able to produce 50% cell lysis up to 100 µM (p < .01). All peptides reduced sperm motility in a dose-dependent manner when used in concentrations from 16 to 64 μM (p < .01). The highest reduction was seen due to K4S4 activity, and the lowest reductions of sperm motility were observed due to K4S4(1–16)a and K4S4(1–15)a activity (p < .01). Hence, we can conclude that K4S4(1–16)a and K4S4(1–15)a at a concentration of approximately 15 µM are the most promising peptides as antibacterial agents in fresh bovine semen, because at this concentration, they showed the most potent antibacterial activity against evaluated strains without significant effects on haemolysis or a reduction in sperm motility.     

A pest risk assessment for Copitarsia spp., Insects associated with importation of commodities into the United States

Summary Eggs and larvae of Copitarsia spp. (Lepidoptera: Noctuidae) are frequently intercepted on fresh commodities arriving in the United States from Mexico, Central America, and South America. Copitarsia spp. are not known to occur in the US and, thus, are considered actionable pests by the US Department of Agriculture, Animal and Plant Health Inspection Service (USDA, APHIS). Whenever the genus is detected in imported goods, shipments must be disinfested, destroyed, or returned to the country of origin. Inspections and interdictions might be unnecessary if Copitarsia spp. were unlikely to establish in the US or if consequences of Copitarsia establishment were trivial. Consequently, we prepared a qualitative pest risk assessment to characterize the degree of risk posed by the genus to US agricultural and natural ecosystems. Published literature was consulted to describe the biology and ecology of the genus. Trade statistics and interception records were summarized to identify pathways of introduction. With this information, experts assigned risk ratings to each of eleven elements identified by USDA, APHIS that pertained to the likelihood or consequence of exotic-pest establishment. The likelihood of Copitarsia spp. becoming established in the US was considered high, but confidence in this assessment was low. Similarly, consequences of Copitarsia establishment were rated high, but confidence in this assessment was moderate. Overall, the assessment revealed that Copitarsia pose a high degree of risk to the US and phytosanitary measures to exclude the pest seem warranted. However, additional research is needed to address critical data gaps and refine assessments of risk for individual species within the genus.     

Flow injection potentiometric system for the simultaneous determination of inositol phosphates and phosphate: phosphorus nutritional evaluation on seeds and grains

A simple flow injection potentiometric (FIP) system, which uses a tubular cobalt electrode, has been developed for phosphorus nutritional evaluation of seeds and grains. Inorganic phosphorus, P(i), is determined using a 1 x 10(-2) mol.L(-1) potassium phthalate buffer solution adjusted at pH 4. A sensitivity of 47 mV/decade and an operating range from 10 to 1000 mg.L(-1) (1 x 10(-4)-1 x 10(-2) M) of dihydrogen phosphate are obtained. The inositol phosphates amount, which is referred to the organic phosphorus, P(org), is directly determined from extracts using a 1 x 10(-2) mol.L(-1) Tris-HCl buffer solution adjusted at pH 8. A sensitivity of 127 mV/decade and an operating range of 10-1000 mg.L(-1) (2.5 x 10(-4)-5 x 10(-3) M) of P(org) (expressed as inositol hexakisphosphoric acid monocalcium) are achieved. Some samples of seed and grain are analyzed by an ICP-OES and a spectrophotometric method to compare results to the developed flow system; no significant differences at the 95% confidence level are observed using a paired t test. Other samples such as animal nursing feed, soybean meal, and corn are also analyzed with the proposed FIP system, showing a good correlation to the ICP-OES values.     

Simulating the effects of different disturbance regimes on Cortaderia selloana invasion

Disturbances favour plant invasions because they provide a pulse of resources for seedling establishment and growth. However, little attention has been paid to the importance of the different disturbance regimes in the extent of invasion. In this paper we asked to what extent invasion depends on spatial and temporal patterns of disturbance. By using the spatially explicit model Fateland, we simulated how Cortaderia selloana, a large-wind dispersed perennial grass invading Mediterranean grasslands, responds to different medium-term (up to 55 years) disturbance regimes. The different scenarios combine disturbance frequency, extent of disturbance and temporal and spatial disturbance variability, and they roughly mimic real situations of habitat management and disturbances in cultural landscapes.The model predicted that the proportion of invaded area would increase with disturbance frequency. The extent of the disturbance overcame the importance of frequency. Aggregated disturbances randomly distributed in space had a more positive effect on invasion than scattered disturbances at repeatedly fixed locations. Whether the disturbances regularly occurred in time or were irregularly distributed did not influence the percentage of invaded landscape. Our simulation analysis unambiguously supports the hypothesis that disturbances are essential for the persistence and expansion of Cortaderia sellona. The high amount of seed rain from a few individuals (e.g., gardens) make this species very sensitive to landscape changes produced by different disturbance patterns (e.g., land abandonment, habitat management or rubbish dumping). Our results can contribute to redirect land management options.     

Genetic control and mapping of Solanum chilense LA1932, LA1960 and LA1971-derived resistance to Tomato yellow leaf curl disease

Tomato yellow leaf curl disease (TYLCD) is caused by a complex of begomovirus. Breeding for resistance to this disease has mainly been based on Ty-1 gene, derived from Solanum chilense LA1969. Commercial varieties available to date still develop symptoms and suffer yield losses with high inoculum pressure and early infections. It is of interest to incorporate in breeding programs resistance from the different available sources. Lines with resistance to TYLCD derived from S. chilense accessions LA1932, LA1960 and LA1971 were previously developed. The objectives of this work were to study the genetic control of the resistance derived from these accessions and to map the resistance loci. Response to viral infection was assayed in segregating generations derived from these sources. Results obtained were compatible with a monogenic control of resistance. A total of 94 markers were used to locate the S. chilense introgressions in each of the lines. Only the presence of a large introgression in chromosome 6 was common to all lines. Analysis of recombinants allowed localizing the resistance loci in an interval of approximately 25 cM, also common to all five families. This interval includes the region to which two previously S. chilense-derived TYLCD resistance loci have been mapped, the Ty-1/Ty-3 region. This is the first report of LA1960 and LA1971-derived TYLCV resistance loci to be located on chromosome 6. Further work will be done to fine map the loci found in the present work, in order to determine if they are indeed located in the Ty-1/Ty-3 region.