Practice of Estimating Losses Caused By Insect Pests to the Small Grains in Russia

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Abstract
The practical need of determining losses caused by insect pests is recognized as an important part of the work of Economic Entomologists, Agronomists and Statisticians. Those insect pests which are invisible to a casual observer are probably the most important. In order to determine the losses caused to certain plants by a given insect, an experiment of artificial infestation, with a future comparison of the check plants and infested plants must be made. The difference in weight of the yield of normal check plants and infested plants expressed in percentage is called “Coefficient of Injury” (C). The Coefficient of Injury is quite constant for certain insect pests. The Coefficient of Injury caused by a given insect might, and really should, be determined by experiments in a laboratory and must be done so once and for all. The percentage of infested plants, or stems of plants in the field, is called “Percentage of Infestation” (P). Percentage of decrease in the yield, or “Percentage of Loss” (L) caused by a certain insect pest to a given crop in the field may be determined from the formula. The “Actual Yield” (A) per acre of a certain field and the “Possible (theoretical) yield” (Y) of grain from the same field when not infested may be also learned from the formula. The “Actual Loss” (X) caused by insect pests is the difference between theoretical and actual yields. To know the exact cost of feeding a certain insect pest is especially valuable, if determined correctly. The quantitative side of the loss caused by insect pests is tremendous, but as yet unknown to the general public.

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