Optimizing aphid biocontrol with the predator Aphidoletes aphidimyza,based on biology and ecology

Aphidoletes aphidimyza is one of the most important predators used in the augmentative biological control of aphids, key pests of many crops worldwide. Adult females are very efficient in locating aphid infestations over a relatively long range, up to 45 m, and deposit eggs near or within aphid colonies. The predatory larvae are aphid generalists preying on several agriculturally important aphid species. The successful use of this biocontrol agent in agricultural systems depends on several biotic and abiotic factors. Among biotic factors, aphid species, plant structure, interspecific competition and intraguild predation may significantly impact the predator´s population dynamics. Key abiotic conditions include day lengths (above a critical threshold to prevent diapause), availability of mating sites in the crop, temperature (above 15 °C to enable egg laying), air relative humidity (above 70%) and availability of pupation sites. Although several successes have been reported in open field crops with naturally occurring or released populations, commercial releases are primarily used in protected crops. Optimized emergence boxes combining provisioning of food sources for the adults, integration with the technological advances that occurred in the greenhouse environment lately, insights into the nutritional ecology in open field crops and exploration of the genetic variability are proposed as future directions to improve adoption and efficacy of A. aphidimyza in crop protection. © 2018 Society of Chemical Industry     

The effects of the severe drought of 1976 on the vegetation of some moorland pools in The Netherlands

The effect of the extreme drough of 1976 has been studied to obtain information on the reaction of the vegetation of moorland pools following a fall in the ground water level. The degree of change appeared to be dependent on the nutrient status of water and soil and on the relief. The vegetation of metatrophic and guanotrophic moorland pools showed the most drastic change.     

Chlorophyll <Emphasis Type="Italic">a</Emphasis> fluorescence,under half of the adaptive growth-irradiance,for high-throughput sensing of leaf-water deficit in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> accessions

Background

Non-invasive and high-throughput monitoring of drought in plants from its initiation to visible symptoms is essential to quest drought tolerant varieties. Among the existing methods, chlorophyll a fluorescence (ChlF) imaging has the potential to probe systematic changes in photosynthetic reactions; however, prerequisite of dark-adaptation limits its use for high-throughput screening.

Results

To improve the throughput monitoring of plants, we have exploited their light-adaptive strategy, and investigated possibilities of measuring ChlF transients under low ambient irradiance. We found that the ChlF transients and associated parameters of two contrasting Arabidopsis thaliana accessions, Rsch and Co, give almost similar information, when measured either after ~20 min dark-adaptation or in the presence of half of the adaptive growth-irradiance. The fluorescence parameters, effective quantum yield of PSII photochemistry (Φ_PSII) and fluorescence decrease ratio (R _FD) resulting from this approach enabled us to differentiate accessions that is often not possible by well-established dark-adapted fluorescence parameter maximum quantum efficiency of PSII photochemistry (F _V/F _M). Further, we screened ChlF transients in rosettes of well-watered and drought-stressed six A. thaliana accessions, under half of the adaptive growth-irradiance, without any prior dark-adaptation. Relative water content (RWC) in leaves was also assayed and compared to the ChlF parameters. As expected, the RWC was significantly different in drought-stressed from that in well-watered plants in all the six investigated accessions on day-10 of induced drought; the maximum reduction in the RWC was obtained for Rsch (16%), whereas the minimum reduction was for Co (~7%). Drought induced changes were reflected in several features of ChlF transients; combinatorial images obtained from pattern recognition algorithms, trained on pixels of image sequence, improved the contrast among drought-stressed accessions, and the derived images were well-correlated with their RWC.

Conclusions

We demonstrate here that ChlF transients and associated parameters measured even in the presence of low ambient irradiance preserved its features comparable to that of measured after dark-adaptation and discriminated the accessions having differential geographical origin; further, in combination with combinatorial image analysis tools, these data may be readily employed for early sensing and mapping effects of drought on plant’s physiology via easy and fully non-invasive means.

     

Expression of Marek's disease virus phosphorylated polypeptide pp38 produces splice variants and enhances metabolic activity

The phosphorylated polypeptide (pp)38 of oncogenic Marek's disease (MD) herpesvirus (MDV) is expressed during lytic infections in vivo and in vitro, but its functions have not been fully elucidated. The quail cell line QT-35, latently infected with MDV, was used to generate QTP32 in which pp38 is expressed under control of a tetracycline controlled promoter to examine possible functions of pp38. Induction of pp38 did not influence late MDV genes expression, but it enhanced mitochondrial dehydrogenase activity significantly. Two new pp38 splice variants were found in induced QTP32 cells, in additional in vitro systems and MDV-infected chickens. Differential expression of full-length pp38 and splice variants suggests that the splice variants are important during latency and perhaps transformation. Polypeptides of 40 and 20kDa were detected by Western blot using monoclonal antibody H19. These polypeptides were also produced in DF-1 cells transfected with a pp38 construct in which the splice acceptor sites had been mutated. Our results add important new information to the role of pp38 in the pathogenesis of MD. The data suggest that pp38 and the two newly described splice variants may influence metabolic activity, which may have important consequences for the understanding of latency and tumor development.     

Detection of chicken anemia virus DNA in embryonal tissues and eggshell membranes

Chicken infectious anemia virus (CIAV) is a ubiquitous and highly resistant virus of chickens that causes anemia and death in chicks less than 3 wk of age and immunosuppression in chickens older than 3 wk of age. The production of specific-pathogen-free eggs free of CIAV is essential for research and vaccine production. Currently, flocks are screened for CIAV by antibody tests to ensure freedom from CIAV infection. Recent evidence, however, indicates that chickens may carry and vertically transmit CIAV DNA independently of their antibody status. In this study, we tested embryos and eggshell membrane residues by nested polymerase chain reaction (PCR) as a sensitive method of detecting CIAV DNA. CIAV DNA could be detected in the blastodisks and semen obtained from antibody-positive and -negative chickens. Examination of different tissues between 18 and 20 days of incubation indicated that many but not all organs of individual embryos were positive. The lymphoid organs and gonads had the highest incidence of CIAV DNA, which was significantly different (P < 0.05) from the incidence in the liver. Eggshell membrane samples from embryos or newly hatched chicks were an excellent noninvasive source for the detection of CIAV DNA, identifying significantly more positive embryos than did pooled lymphoid organs. The use of dexamethasone injections as a method to improve the detection of carrier birds did not result in an increase of vertical transmission or cause seroconversion in the treated hens. A combination of testing eggshell membrane residues at hatch and periodic testing of blood DNA by nested PCR can be used to identify chickens carrying CIAV DNA and may be used to eradicate carrier birds.     

Contribution to the knowledge of the families apionidae and nanophyidae (Coleoptera: Curculionoidea) from Turkey, with new records

Data are presented on the occurrence of 43 species of the family Apionidae and two species of the family Nanophyidae in Turkey based on the material obtained mainly by beating stone-fruit trees in NE Turkey. The identity and information about the three species of Apionidae —Squamapion sp.cf.bifarium (Balfour-Browne),Protapion sp.cf.ruficrus (Germar),Catapion sp.cf.seniculus (Kirby) — must be revised. The faunistic data in the present paper on almost all species add to prior knowledge on their distribution in Turkey.Hypophyes aphyllae (Peyerímhoff),Ceratapion kasbekianum (Gerstaecker),Squamapion ottonis (Wagner),S. samarense (Faust),S. phocopus (Eppelsheim),Taeniapion rufulum (Wencker),Pseudoprotapion astragali (Paykull),P. ergenense (Becker),Stenopterapion intermedium (Eppelsheim) andOxystoma fausti (Desbrochers) are reported for the first time in the Turkish fauna. http://www.phytoparasitica.org posting Nov. 8, 2001.     

防治免疫抑制性疾病的新策略

要生产出健康的鸡群很大程度上取决于传染性疾病的控制.新疫苗技术的开发或培育出能抵抗免疫抑制性疾病的转基因鸡,在技术上已成为可行,但是这在经济上尚不能令人满意.