Beaulieu C, Lavoie C, Proulx R. 2018. Bookkeeping of insect herbivory trends in herbarium specimens of purple loosestrife (Lythrum salicaria).

The potential use of herbarium specimens to detect herbivory trends is enormous but largely untapped. The objective of this study was to reconstruct the long-term herbivory pressure on an invasive plant, purple loosestrife (Lythrum salicaria), by evaluating leaf damages over 1323 specimens from southern Québec (Canada). Historical trends suggest a gradual increase in hole feeding and margin feeding damages from 1883 to around 1940, followed by a period of relative stability. The percentage of specimens with window feeding damages did not begin to increase until the end of the 20th century, from 3% (2 ̶ 6%) in 1990 to 45% (14 ̶ 81%) in 2015. Temporal changes in the frequency of window feeding damages support the hypothesis of an increasing herbivory pressure by recently introduced insects. This study shows that leaf damages made by insects introduced for the biocontrol of purple loosestrife, such as coleopterans of the Neogalerucella genus, can be assessed from voucher specimens. Herbaria are a rich source in information that can be used to answer questions related to plant-insect interactions in the context of biological invasions and biodiversity changes.

利用标本馆标本（herbarium specimens）探究植食性动态（herbivory）的潜力巨大，但目前尚未得到充分挖掘。本研究旨在通过评估加拿大魁北克南部1323份标本的叶片受损情况，重建入侵植物千屈菜（Lythrum salicaria，俗称purple loosestrife）所承受的长期植食压力。历史趋势显示，1883年至1940年左右，虫孔取食（hole feeding）与叶缘取食（margin feeding）造成的叶片受损情况呈逐步上升趋势，随后进入相对稳定的阶段。带有窗状取食（window feeding）受损痕迹的标本占比直到20世纪末才开始上升，从1990年的3%（2%~6%）升至2015年的45%（14%~81%）。窗状取食受损频率的时间变化，支持了“新近传入的昆虫导致植食压力上升”这一假说。本研究表明，针对千屈菜开展生物防治（biocontrol）而引入的昆虫（如Neogalerucella属鞘翅目昆虫（coleopterans））所造成的叶片受损情况，可通过凭证标本（voucher specimens）进行评估。标本馆蕴藏着极为丰富的信息资源，可用于解答生物入侵（biological invasions）与生物多样性变化（biodiversity changes）背景下的植物-昆虫互作（plant-insect interactions）相关科学问题。