Ohsawa Masashi
Yamanashi Forest Research Institute, 2290-1 Saisho-ji, Fujikawa-cho, Minamikoma-gun, Yamanashi 400-0502, Japan.
Insects. 2017 Mar 24;8(2):35. doi: 10.3390/insects8020035.
This study was conducted to elucidate the life cycle and the ecological characteristics of Y. Kurosawa, an important pest of (Thunb.) Makino. Life cycle, mortality rates in developmental stages, annual population dynamics, and early leaf abscission were investigated. Adults emerged from under the bark of trees in April and fed on leaves. Females laid 49 eggs on average, mainly in May and early June. Eggs hatched after 17 days, and the larvae fed inside the leaves. They developed through three instars. In July, leaves with the final stage of larvae were abscised. Four days after abscission, the larvae pupated. New adults eclosed from pupae seven days after pupation, and the adults emerged from abscised leaves after an additional two days. In total, 1650 adults emerged per 1 m² of forest floor, resulting in a major population increase. The newly emerged adults fed on the remaining leaves, compounding the damage. In October, adults overwintered under the tree bark. Mortality rates in the egg, larval, and pupal stages were 41%, 58%, and 31%, respectively. The mortality rate among overwintering individuals was 43%. Because only leaves that were abscised in July contained the larvae, and because only a small number of beetles emerged from non-abscised, mined leaves, the removal of abscised leaves at nine-day intervals over period of early leaf abscission is a simple and effective way to control the beetle.
本研究旨在阐明黑泽叶甲（Y. Kurosawa）的生活史及生态特征，黑泽叶甲是（Thunb.）牧野的一种重要害虫。研究了其生活史、发育阶段的死亡率、年种群动态以及早期落叶情况。成虫于4月从树木树皮下方羽化而出，以树叶为食。雌虫平均产卵49枚，主要在5月和6月初。卵在17天后孵化，幼虫在叶片内取食。它们经过三个龄期发育。7月，处于幼虫末期的叶片脱落。落叶4天后，幼虫化蛹。化蛹7天后新成虫从蛹中羽化而出，再过2天成虫从脱落的叶片中羽化。每1平方米林地共羽化出1650只成虫，导致种群大幅增加。新羽化的成虫取食剩余的树叶，加剧了危害。10月，成虫在树皮下方越冬。卵期、幼虫期和蛹期的死亡率分别为41%、58%和31%。越冬个体的死亡率为43%。由于只有7月脱落的叶片中含有幼虫，且只有少量甲虫从未脱落的、有虫蛀的叶片中羽化，因此在早期落叶期每隔9天清除脱落的叶片是控制该甲虫的一种简单有效的方法。
