Relationship between abundance of rodents and damage to agricultural crops

Developing a relationship between pest abundance and damage to crops is essential for the calculation of economic injury levels (EIL) leading to informed management decisions. The crop modelling framework, APSIM, was used to simulate the impact of mouse damage on yield loss on wheat where a long-term dataset on the density of mice was available (1983–2003). The model was calibrated using results from field trials where wheat plants were hand clipped to imitate mouse damage. The grazing effect of mice was estimated using the population density, daily intake per mouse and the proportion of wheat grain and plant tissue in the diet to determine yield loss. The mean yield loss caused by mice was 12.4% (±5.4S.E.; range −0.5 to 96%). There were 7/21 years when yield loss was >5%. A damage/abundance relationship was constructed and a sigmoidal curve explained 97% of variation when accounting for different trajectories of mouse densities from sowing to harvest. The majority of damage occurred around emergence of the crop when mouse densities were >100 mice ha⁻¹. This is the first time that field data on mouse density and a crop simulation model have been combined to estimate yield loss. The model examines the efficacy of baiting and how to estimate EILs. Because the broadscale application of zinc phosphide is cheap and effective, the EIL is very low (<1% yield loss). The APSIM model is highly flexible and could be used for other vertebrate pests in a range of crops or pastures to develop density/damage relationships and to assist with management.     

Besteht die Möglichkeit zur Übertragung von AIDS durch blutsaugende Insekten?

The question whether the possibility exists of transmission of HIV by hematophagous insects from infected to uninfected persons is a point of very intensive discussion. The solution of this problem could help to explain the spreading of the disease in human populations and could contribute to an understanding of the evolution of AIDS and the possible transfer from wild primates into human populations. The classical routes of pathogen transmission by blood-sucking arthropods are either "mechanical" or "biological". Both ways are rejected, the latter since no replication of the retro-virus in the vector exists and its survival in the arthropod is very limited. Based on long experimental experience with biting flies as well as with plant-sucking insects a third hitherto neglected way of transmission by regurgitation of gut content can be introduced. Since regurgitation is neither "mechanical" nor "biological", "regurgitative transmission" must be introduced as an additional term.     

Extreme34S-Anreicherungen in gelöstem Sulfat von Grundwässern im Umfeld einer Altmülldeponie

Wir danken Dr. Kerndorff für die kritische Durchsicht des Manuskripts.     

The selection of management strategies for controlling nematodes in cereals

Several genera and species of plant-parasitic nematodes cause losses in grain yield in cereals; some are of relatively minor importance (e.g. Anguina tritici (Steinbuch) Chitwood, the cause of “ear cockle” in wheat), while others such as the cereal cyst nematode (CCN) (Heterodera avenae Woll.) have a wide geographic distribution, infest extensive areas, and may cause losses valued at millions of dollars. Some of these nematodes are difficult to control because the measures that might be used are uneconomic to apply or are impractical. The control of CCN, however, can be achieved, and several successful strategies have been developed in parts of Europe and in Australia. The various measures available to Australian cereal growers include: crop rotation, resistant cultivars, manipulation of sowing dates, use of nematicides, and reduced cultivation. The selection of an appropriate management strategy for the control of CCN is influenced by factors such as: climate, cereal species grown, yield potential, rotations practised and the availability of alternative crops, pathotype present, farm size, availability of resistant cultivars, nematicides registered, and the availability of suitable equipment for their application.     

Activities of alkaline phosphatase in first trimester chorion biopsy tissue

We have determined the activity of alkaline phosphatase in chorionic villous tissue obtained in the first trimester of pregnancy, in order to obtain the normal range of values as a prerequisite for application to the prenatal diagnosis of the rare bone disease hypophosphatasia. The activities found were a combination of intestinal and liver/bone/kidney types; traces of placental type were present in only one sample.     

Assessment and management of fetal agenesis of the corpus callosum

Prenatal counselling for fetal agenesis of the corpus callosum is difficult as the prognosis until now has been so uncertain. We have reviewed the current world English literature to provide the best probabilistic information for prospective parents. In total, there are 70 cases where the diagnosis was made prenatally. The diagnosis of apparently isolated agenesis of the corpus callosum (in the absence of other sonographically detectable anomalies) appears to carry an excellent prognosis, with an 85 per cent chance of a normal developmental outcome and a 15 per cent risk of handicap. Fetal karyotyping is recommended as there is a 1 in 10 risk of aneuploidy. If other anomalies are detected prenatally, the outcome is very poor. Termination of pregnancy is advised in these circumstances.