Antagonism of local isolates of Trichoderna spp. on citrus root rot disease by Fusarium solani in the mekong delta of vietnam

The local isolates of Trichoderrma spp. and Fusariun solani were colected from citrus orchards in the Mekong delta of Vietnam and isolated on PDA, PDB and TSM medium for antagonism and Koch's postulate testing. The results showed that the high chitinolytic enzymes content of Trichoderma isolates can antagonise with Fusarium solani isolates by preventing the germination of Fusarium macroconidia in in-vitro condition. There are five promising isolates of Trichoderna spp. having high antagonism with Fusarium solani. These Trichoderma isolates also grew well in rice straws, maize stems, weeds and water hyacinth biowaste materials. These results supply the promising trend for biological control of root rot disease on citrus orchards of the Mekong delta.     

Rural livestock asset portfolio in northern Ethiopia: a microeconomic analysis of choice and accumulation

Livestock fulfill different functions. Depending on their livelihood strategies, households differ in their choice of what type of animal to keep and on accumulation of the chosen animal overtime. Using a panel data of 385 rural households in a mixed farming system in northern Ethiopia, this paper investigates the dynamic behavior of rural households’ livestock holding to identify determinants of choice and accumulation of livestock overtime. Choice is analyzed for a principal animal, the animal that constituted the largest value of livestock assets a household possessed, using a multinomial logit model. Results indicate that rural households differ in their choice of what type of animal to keep. Agro-climatic conditions, sex and age of household head, presence of an adult male member in a household, and liquidity are the major factors that influence the type of principal animal households keep. Conditional on the principal animal selected, we analyzed the factors that determine the accumulation of the chosen animals by correcting for selection bias. Area of land cultivated is the most significant factor that explains the number of animals households keep. Other factors include sex of household head, diversification into nonfarm self-employment, and shocks.     

Evaluation of a serodiagnostic test using Ascaris suum haemoglobin for the detection of roundworm infections in pig populations

The significant economical consequences of infections with Ascaris suum in pigs are already well documented. However, due to the subclinical nature of the disease and the lack of practical diagnostic means, ascariasis often remains undiagnosed. Here we describe the development and evaluation of a novel indirect ELISA using the purified A. suum haemoglobin (AsHb) molecule as an antigen. Initial validation using sera from 190 pigs experimentally infected twice a week with A. suum and Trichuris suis (25 and 5eggskg(-1)day(-1) respectively) demonstrated that the AsHb ELISA is able to detect long-term exposure to A. suum with a high sensitivity and specificity (99.5% and 100.0% respectively). Furthermore, this serological technique proved to be more sensitive than faecal examination on week 7 and 14 of the experiment (99.5% and 100% compared to 59.5% and 68.4% respectively). Cross-reactivity caused by T. suis infection was shown to be limited after analysing sera from pigs with an experimental T. suis mono-infection. Seroconversion was shown to occur from week 6 onwards in pigs receiving 100 A. suum eggs 5 times a week. Preliminary testing of the ELISA on six randomly selected farms confirmed the results obtained in the artificial infection trials, showing a higher sensitivity of the serologic method compared to faecal examination. Finally, the ELISA was used to investigate Ascaris infection rates on 101 conventional Flemish pig farms. The results showed that on 38.6% of the farms less than 20% of the tested samples were seropositive, while in 19.8% of the farms 80-100% of all pigs were seropositive. The results of this study suggest that the AsHb ELISA could provide pig farmers and veterinarians with an easier and more sensitive way to estimate the overall prevalence of A. suum on their farm.     

Spatial structures of soil organic carbon in tropical forests—A case study of Southeastern Tanzania

Southeastern Tanzania serves as a typical example of soil degradation and soil organic carbon (SOC) losses on the African continent. Although sequestration of SOC through aforestation or reforestation proved favorable, these measures are restricted by the ability to produce rapid, cost-effective and precise sampling schemes. The aim of this study is to contribute to a better knowledge of the spatial distribution of soil C in tropical natural and plantation forest. This paper presents sampling strategies for estimating mean SOC values as well as for SOC mapping, based on different methods for SOC determination and on different precision levels. To do so we conducted a carbon variability study in five common forest types of Southeastern Tanzania (coastal dry forest, Miombo woodland, teak plantation, pine plantation and cashew plantation) using conventional statistical methods, as well as geostatistics. In the 5 forest types of this study, SOC stocks in the upper 5 cm ranges between 5 (in the cashew plantation) and 13 (in the coastal forest) t ha^− 1. The optimal sampling distance for measuring mean SOC stocks varies between 36 m (in the patchy miombo woodland) and 422 m (in the homogenized cashew plantation). Sample sizes fluctuate between 6 and 72 (1 t ha^− 1 precision) for respectively cashew plantation and coastal forest. A rectangular grid with a sample interval of 25 m can be used for SOC mapping with a point kriging estimation error of 3.0 t ha^− 1 in the coastal forest, 2.6 t ha^− 1 in miombo woodland, 2.2 t ha^− 1 in the teak plantation and 1.1 t ha^− 1 in the cashew plantation. Since the pine plantation has no spatial structure; samples can be arranged randomly and its best soil map has an average C content attributed over the whole field. Refining the sampling strategy with a new spatial variability study in other forest types can be based on a regular grid with sampling distances of half the range identified in this study. This paper proves that the optimal sampling scheme varies strongly as a result of the different spatial behavior of SOC in forests and depends on the required precision and research question. Only when the right strategy is followed, high standards of precision can be met without economic loss or risk of statistical misinterpretation.     

Sediment yield variability in Northern Ethiopia: A quantitative analysis of its controlling factors

In Tigray-northern Ethiopia, lack of sediment yield data and appropriate methodologies for predicting sediment yield have contributed to poor planning resulting in rapid sedimentation in reservoirs and storage capacity loss. The objectives of this study were: (1) to assess the spatial variability of absolute sediment yield (SY) and area-specific sediment yield (SSY) and to identify their controlling factors for 11 representative catchments and (2) to develop models to predict sediment yield. We quantified sediment yield from reservoir sediment surveys and studied the role of bio-physical characteristics of the catchments and their interactions in controlling SY and SSY variability.     

Invasive and quarantine pests in forests in Slovakia1

Biological invasions of insects, plants, and fungal pest species often cause substantial disturbance to forest ecosystems and as well as severe socioeconomic impacts. Central Europe acts as a ‘bridge’ between Western and Eastern Europe both ecologically and as an important transit corridor for people. Human activity, including the movement of material goods, increases the risk of invasions. Some species introduced in the past have been established, becoming common and causing serious problems (such as Dreyfusia nordmannianae or Hyphantria cunea). The status, importance and spatial distribution in Slovakia of seven different forest pests recently introduced into Slovak forest ecosystems (Cameraria ohridella, Coleotechnites piceaella, Cryphonectria parasitica, Dothistroma septospora, Ips duplicatus, Parectopa robiniella, Phyllonorycter robiniellus) as well as two others not yet recorded in Slovakia (Anoplophora glabripennis, Phytophthora spp.) is discussed.     

Parasitic Ichneumonoidea on the horse chestnut leaf miner, Cameraria ohridella (Lepidoptera: Gracillariidae) in Slovakia

Parasitic Hymenoptera from the suprafamily Ichneumonoidea attacking the horse chestnut leafminer Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae) were studied in southwest Slovakia during 2000 and 2001. The search for such species resulted in the determination of eight ichneumonid species, Gelis agilis (Fabricius), Itoplectis alternans (Gravenhorst), I. clavicornis (Thompson), I. maculator (Fabricius), Scambus annulatus (Kiss), S. brevicornis (Gravenhorst), Zatypota percontatoria (Müller), Adelognathus sp. and a braconid Colastes braconius Haliday. The most abundant species was S. annulatus. All these species recorded are polyphagous and often facultative hyperparasitoids, except C. braconius, which departs from this norm in not being hyperparasitic. The presence of more diversified native parasitoids and hyperparasitoids from the Ichneumonoidea predicate a slow successive adaptation of the parasitoid fauna to the invasive host, Cameraria ohridella.     

Heavy Metal Concentrations,Partitioning, and Storage in Slovak Forest and Arable Soils Along a Deposition Gradient

Along a heavy metal deposition gradient, caused by a Cu smelter, heavy metal concentrations, partitioning, and storage in forest and arable soils were examined. We sampled organic and mineral soil horizons (0—50 cm) at ten pairs of forest and arable sites derived from the same parent material. A-horizons were extracted with a seven-step sequence; O- and subsoil horizons were digested with strong acids (HNO₃/HClO₄). We found high concentrations of Cd (up to 17.38 mg kg^—1 in the O horizons/up to 2.44 mg kg^—1 in the A horizons), Cu (8437/415), Pb (3343/126), and Zn (1482/637) which decreased exponentially with distance from the smelter and with soil depth. The metal concentrations in the organic layers indicate that the average transport distance decreases in the order Cd > Zn > Pb > Cu. With regard to metal partitioning, NH₄NO₃- + NH₄OAc-extractable forms in the A horizons were most affected by the deposition being more pronounced under forest. In the uppermost 50 cm of the four soils nearest to the smelter two to four times higher Cd, Cu, Pb, and Zn storages were found in forest than in arable soils. At greater distance, the higher deposition onto forest soils due to the scavenging effect of the canopy obviously was compensated by stronger leaching.     

Glass Transition Behavior and Rheological Properties of Surfactants and Gluten‐Surfactant Mixtures

Diacetyltartaric acid esters of monoglycerides (DATEM) and sodium stearoyl lactylate (SSL) displayed thermal events corresponding to glass transition temperature (T_g) and melting of crystalline domains, while monoglycerides (MG) exhibited an endothermic peak corresponding to melting of crystalline structures when heated in a differential scanning calorimeter. The plasticizing effect of water on T_g of gluten exhibited little apparent change in the presence of DATEM, MG, or SSL (glutensurfactant 10:1), in the moisture range of 6.5–21.3% as shown by mechanical spectrometry and differential scanning calorimetry. Glutensurfactant mixtures showed higher G′ and apart from gluten‐SSL, which displayed higher tan δ (G″/G′) at ≤2.51 rad/sec, lower tan δ values than gluten in the frequency range of 0.1–100 rad/sec. DATEM and SSL softened the gluten network before cross‐linking reactions, while MG shifted the onset of cross‐linking reactions to higher temperatures at moisture contents of 30–40%. Complete vitrification of the gluten network occurred at higher temperatures, at the indicated moisture contents, in the presence of surfactants. Softening of the matrix and the delay in cross‐linking of gluten, in the presence of surfactants, might allow for greater expansion of doughs during baking with concomitant increase in loaf volumes.     

The distribution of <Emphasis Type="Italic">Obolodiplosis robiniae</Emphasis> on black locust in Slovakia

For the first time during October 2006, the occurrence of Obolodiplosis robiniae (Haldeman 1847) (Diptera: Cecidomyiidae) was recorded on the black locust (Robinia pseudoacacia L.) in Slovakia. During 2007, field surveys were undertaken to determine the distribution of the species and the infestation ratio at different locations. One year after its first discovery, O. robiniae was found throughout southern Slovakia. The gall midge was observed in 148 out of 161 checked locations. The infestation ratio of single leaves varied from 4 to 100%. The infestation ratio of the black locust tree was evaluated during May–June, July–August, and September–October, and accounted for 15–39, 9–53, and 6–49%, respectively. The most frequent infestation ratio fluctuated from 10 to 30% (115 locations). The highest infestation was recorded during July–August. Greater infestation was prevalent in the larger settlements than it was in the countryside. The gall midge was also recorded on R. viscosa Vent. Although the results show that O. robiniae is nowadays an usual insect with high potential to become an important pest of ornamental black locust or biological control agent against weedy black locust in southern Slovakia, the species do not appear to have reached pest status until now.