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Weather sets the basic framework within which certain average but fluctuation insect population densities may be obtained in the absence of other possible regulatory factors. These average population densities may be very high or very low. Weather regulates insect population only by being of sufficient severity to restrict the size, quality (including food and favorability), and/or number s of inhabitable spots in a given area—that is, its effect is obtained through interaction with micro environments. If overlying weather severity in a given spot or area is not relatively great, then, theoretically, populations will be able to increase indefinitely over a period of time unless limited by other factors. Illustrations of population regulation by weather and methods of proof of such regulation are discussed. The other principal factors capable of regulating insect population densities are (1) natural enemies (parasites, predators, and pathogens), (2) food (quantity and quality), (3) inter specific competition (other than natural enemies), and (4) intra specific competition. The last three factors usually do not control populations at low (uneconomic) levels and hence are not generally important factors in applied insect ecology. Natural enemies may regulate insect populations at low levels even if all other factors are exceptionally conducive to increase. Several experimental methods for proving the extent of regulation of incest populations by entomophagous species are given. Thirteen examples of adequate proof of control of low density population regulation of the California red scale by its natural enemies is given. It si shown that "upsets" of natural enemy effectiveness by adverse factors can result in various differing average population densities of the California red scale (Aonidiella aurantii (Mask.), even on adjacent citrus trees.
Document Type: Research Article
Publication date: August 1, 1958
More about this publication?
Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.