콩 재배지 나방류 유충의 기생성 토착천적에 대한 살충제의 독성 평가

초록

This study assessed the insecticide toxicity on two indigenous parasitoids of Noctuid larvae, Exorista japonica and Meteorus pulchricornis. Under laboratory condition, a residual toxicity test was conducted by applying 16 registered insecticides pest control in soybean to crop plants and exposing adult parasitoids to the treated plants at different time intervals. In E. japonica, exposure to plants treated with acrinathrin 5.7% SC at one and three days post-treatment resulted in a mortality rate of 40.0%. However, mortality decreased to 23.3% when exposed to plants seven days after insecticide treatment. For the remaining 15 insecticides, a mortality rate of less than 25% resulted from exposure to E. japonica adults on plants one day post-treatment. This indicate that most insecticides registered for soybean crops are unlikely to have a significant negative impact on E. japonica. Acrinathrin 5.7% SC, demonstrated toxicity to E. japonica as well as a high toxicity to M. pulchricornis, causing a mortality rate of 96.7% when exposed to treated plants one day after insecticide treatment. Furthermore, five insecticides, including flubendiamide 20% SC, and resulting in mortality ranging from 25% to 50%, showed moderate toxicity to M. pulchricornis. Meanwhile, eight insecticides including pyrifluquinazone 6.5% SC with mortality rates below 25% for M. pulchricornis were classified as low-toxicity insecticides. From 2022 to 2024, these two parasitoids were investigated by collecting Spodoptera litura and S. exigua larvae from soybean fields in four counties in Jeollanam-do and Jeollabuk- do. The results revealed that the natural parasitism ranged from 8.1% to 35.0%. Considering the distribution of these indigenous parasitoids in open fields in Korea, their potential pest control use was confirmed. Therefore, to protect and maintain these natural enemies, farmers should selectively use low-toxicity insecticides when applying chemical pest control.

키워드