Pathogenic Microorganisms in the Regulation of Forest Insect Populations

Microorganisms form an important part of the natural forest ecosystem by participating in the recycling of the chemicals and energy of life. Fallen leaves, twigs, branches and trunks do not accumulate but are almost imme­ diately utilized by fungi, bacteria, protozoa, and nematodes and converted into chemicals that may be recycled into the production of new trees. Dead animals, including insects, are recycled in the same manner. Among all these groups of microorganisms certain species are known to be pathogenic, that is, they are able to cause disease in living plants and ani­ mals. For example, many diseases of trees are known to be caused by fungi, and bacterial diseases are common among animals.