2021 年 65 巻 3 号 p. 133-141
Mushroom-like synnemata of the entomopathogenic fungi, Isaria cicadae Miq.（Ascomycota: Hypocreales）, appeared gregariously on the ground of a Fraxinus japonica plantation, Takizawa City, Iwate, Japan, situated 170-km from the known geographic range of the fungi. The synnemata that grew inside the emergence trap for collecting the defoliators in the plantation grew 1.5-times more prominently than those on the outside, which lead to the present discovery. The micro-climate inside the trap was 23.7% darker, 2.8°C milder in the daily temperature changes, and 4.7% moister than that on the outside, which would promote the growth in height. The synnemata emerged uniformly throughout the plantation at a density of 8.86, 4.57, and 1.44/m2 in 2016, 2017, and 2020, respectively. A total of 125 specimens of the hosts dug out from the soil were all the last instar larvae of Meimuna opalifera（Walker）（Hemiptera: Cicadidae）. The number of cicadas killed by the fungi on the plantation of 389 m2 was 3448, 1779, and 564 in 2016, 2017, and 2020, respectively. However, only 2, 5, and 6 cicadas survived in these respective years. The density increased and the catastrophic mortalities of the cicadas were found to be restricted to this plantation.