Monitoring the Health Status of Pest Populations as a Contribution towards the Establishment of Economic Thresholds

Knowledge of pest population dynamics is required to assess the future abundance of a pest, the losses to be expected and the economic threshold. Mortality of pests caused by diseases can greatly influence their development and a valuable assessment can therefore only be based on healthy individuals. Examples of monitoring the health status are usually taken from the forest and from such insects that develop slowly and allow an assessment of the epizootic before the damaging final instar has been reached (caterpillars, sawflies). In agriculture, the tendency of reducing crop rotation increases the permanence of regulative forces and is consequently favourable. This allows for a more precise prediction on the development of epizootics. Recent observations show that appropriate sampling of aphid populations designed to determine their health status in respect to fungal epizootics can greatly increase the accuracy of the forecast on future trends in population dynamics.     

Plasminogen activator activity in secretions from clinically normal, mastitic, lactating and dried-off udders of dairy cows

Using the composite fibrin plates method, plasminogen activator (PA) activity was found in secretions from clinically normal, mastitic, lactating and dried-off udders of dairy cows. The possible involvement of the fibrinolytic system in the physiology and pathology of the bovine mammary gland is discussed.     

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Ergosterol biosynthesis inhibitors. An overview of their history and contribution to medicine and agriculture

Over the past 15 years, an increasing number of ergosterol biosynthesis inhibitors (EBIs) have been introduced in crop protection as fungicides, and in medicine as fungicides and bactericides. Their spectrum of activity and their systemic properties vary widely, depending on structural elements. By their high protective and curative activity the EBIs have greatly improved the level of disease control, both in plants and in man. However, the chemical and biological potential of this group has not yet been fully explored, particularly in the field of growth regulation.     

Comparison of two ruminoscopy techniques in calves

Two different techniques were tested in nine calves to describe endoscopically the visible structures of the rumen and the reticulum. Ruminoscopy using an orally introduced flexible endoscope proved to be unsatisfactory, but when the endoscope was introduced through a ruminal fistula in the left flank into the dorsal and ventral ruminal sacs, the blind sacs, ruminal pillars, the atrium of the rumen, the reticulum and the reticular groove could all be displayed effectively. Indentations of the ruminal wall caused by the left kidney, the spleen and the abomasum could be seen with the endoscope as could reticulo-ruminal contractions. The technique allowed visual evaluation of the mucosal surfaces and movement of the rumen, reticulum and reticular groove. The advantages and disadvantages of ruminoscopy in bovine medicine are discussed.