マイマイガの潜伏発生期における環境抵抗の実験的解析 : 樹木園における生存曲線と死亡要因

概要

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Eggs and larvae of the gipsy moth, L. dispar, were artificially placed on larch and birch trees, both of which were about 2-2.5m height, and the environmental resistance of the population which was kept under a condition of latency was analyzed. Except death by air-borne dispersal in their first instar, most larvae were killed by the predation of birds. The sparrow, Passer montanus kaibatoi MUNSTERJELM, and other birds predated on the larvae over the third instar. At first the predation was caused independently on larval density, but soon it changed to be caused density-dependently. Most of the 260 larvae, which were placed in the egg stage, on 29 larch trees (1-40 larvae on each tree) and 2,200 larvae, which were placed in third instar (20-200 on each tree) were predated density-dependently in their third and forth instars. The 165 larvae of the fifth instar and 125 larvae of the sixth instar having been placed in low density levels (1-20 larvae on each tree) were also immediately predated density-dependently. Parasitisms by Apanteles liparidis were observed, however, as the percentage of the third instar larvae which were parasitized was less than 20 per-cent and the parasites killed the fifth instar larvae, therefore, predation of birds which began in third instar was regarded as the regulatory factor of the population.
日本応用動物昆虫学会の論文
1972-09-25