Principles and strategies of biological control economically harmful forest organisms

Abstract

Essentially, biological control is nothing but applied ecology, ie the use of natural enemies to (regulatory) reduce abundance in pest populations. Intellectually satisfying, biologically intriguing and ecologically rational, a means of pest control, biological control, is one of the areas of integrated management and protection of forest ecosystems, which is rapidly developing and brings together scientists from many disciplines. Ecologists, entomologists, pathologists of plants and insects, microbiologists, approach the subject of research from different angles. Each discipline uses biological control in order to reduce the number of pests or pathogens, through the activity of beneficial living organisms. Biological control of economically harmful forest organisms means that those who decide on its application in specific environmental conditions should first accurately identify the type of pest, assess the level of infestation and predict potential economic damage, explore all available strategies, their advantages and disadvantages, and select the most efficient, which must be in correlation with all applicable local, national and international regulations. Within the biological control of pests, mainly insects, various strategies are used, which basically include the introduction of natural enemies, predators, parasitoids and pathogens, indigenous and allochthonous harmful insect species (classical and inoculation biological control) and increasing their numbers (inundative biological suppression). It should be noted here that the legislation in the field of nature and environmental protection prohibits the introduction of allochthonous, exotic species into natural and anthropogenic ecosystems in many countries, and therefore, the application of biological control is quite limited. A special, promising, strategy within biological control is the selection of strains with genetically induced ability of autocidal action. Entomopathogenic organisms, various types of viruses, microsporidia, bacteria, protozoa, fungi, which under favorable conditions can cause mass death of insects, live normally in nature and are important regulatory factors in host populations. Epizootics caused by natural viral and fungal pathogens are often responsible for spectacular crashes in populations of graded species, e.g. gubara, žutotrbe, ordinary and red pine sol. Despite such brilliant characteristics, a small number of them are included in certain biological control strategies. Suppression of plant pathogens can rarely be achieved without a careful combination of many techniques. Legislation in the field of nature and environmental protection in many countries prohibits the introduction of non-native, exotic species, and thus, the application of a number of biological control strategies is prevented.The application of fungicides in forest ecosystems is usually too expensive, so biological control measures are preferred, through the use of antagonistic or hypovirulent species of microorganisms and their strains. In essence, when it comes to plant pathogens, biological control measures are more preventive than palliative or curative, and are based on sustainable ecological concepts of forest ecosystems.