アズキゾウムシについてのとり除きとつけ加えによる個体群平衡密度の研究

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It was tested in the experimental population of the azuki bean weevil, Callosobruchus chinensis, whether a balance of population exists when the density independent mortality such as constant percentage of artificial removing or adding influence the population. The experiment was done under the controlled condition of 30℃ and 75 per cent R.H. supplying with a constant amount of azuki bean as food. In the present experiment, various percentages of insects were removed from or added to such population in every generation, and it was analysed how the steady state is altered under such a condition. Removal of a given percentage of weevil was made in every generation by heat treatment of required percentage of the bean which contained the insect, just before the adults emergence. Removing were 0,25,50,75,90 per cents of the level of steady density (Experiment A). Adding the insects into the population was during the first six days of the emergence period, in which number of adults added were determined as percentage of expected level of steady state in the control culture. Percentage of adding were 0,25,50,75,100 (Experiment B). In any case of the removing or adding, the population maintains a steady level of population density, and in some cases, damping oscillation was obserbed, and the level of population is concave to upwards or convex downwards before the population reached a steady state. The more increase of removing or adding percentage follows the more compensatory rise or fall of the steady density (Fig. 1,2). Several generations were required before the population reached its steady state, but when the strong disturbance of the population as 90 per cent removing was done, and the variation of the steady level of the population was enlarged in four replicates, and the population was difficult to reach its steady state after several generations elapsed (Fig. 3). From such affairs, it should seem that the chance element is important when strong a disturbance may influence population. The rate of reproduction between two consecutive generations was dependent on the intensity of competition and varied from 11.75 in 90 per cent removing the population to 0.48 in 100 per cent adding population (Fig. 4). The result of this experiment clearly indicates that a balance of the population exists, and the insect population must be in a balance with the density independent condition to which they are subjected at any density.
日本生態学会の論文
1962-08-01

アズキゾウムシについてのとり除きとつけ加えによる個体群平衡密度の研究

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