Department of Biology, University of Turku, 20014, Turku, Finland.
Herbarium, V. L. Komarov Botanical Institute, Professora Popova Str. 2, 197376, St. Petersburg, Russia.
Sci Rep. 2020 Jul 23;10(1):12298. doi: 10.1038/s41598-020-69195-5.
Information regarding plant damage by insects in the past is essential to explore impacts of climate change on herbivory. We asked whether insect herbivory measured from herbarium specimens reflects the levels of herbivory occurring in nature at the time of herbarium sampling. We compared herbivory measurements between herbarium specimens collected by botany students and ecological samples collected simultaneously by the authors by a method that minimized unconscious biases, and asked herbarium curators to select one of two plant specimens, which differed in leaf damage, for their collections. Both collectors and curators generally preferred specimens with lesser leaf damage, but the strength of this preference varied among persons. In addition, the differences in measured leaf damage between ecological samples and herbarium specimens varied among plant species and increased with the increase in field herbivory. Consequently, leaf damage in herbarium specimens did not correlate with the actual level of herbivory. We conclude that studies of herbarium specimens produce biased information on past levels of herbivory, because leaf damage measured from herbarium specimens not only underestimates field herbivory, but it is not proportional to the level of damage occurring in nature due to multiple factors that cannot be controlled in data analysis.
有关过去昆虫对植物造成损害的信息对于探究气候变化对食草作用的影响至关重要。我们想知道从植物标本中测量到的昆虫食草情况是否反映了植物标本采集时自然界中实际发生的食草水平。我们比较了由植物学学生采集的植物标本和作者同时通过最小化无意识偏见收集的生态样本之间的食草情况，并且请植物标本馆管理员从两个具有不同叶片损伤的植物标本中选择一个用于他们的收藏。收集者和管理员通常更喜欢叶片损伤较小的标本，但这种偏好的强度因个人而异。此外，生态样本和植物标本之间的叶片损伤测量值的差异因植物物种而异，并随着野外食草量的增加而增加。因此，植物标本中的叶片损伤与实际的食草水平没有相关性。我们得出结论，对植物标本的研究产生了有关过去食草水平的有偏差的信息，因为从植物标本中测量到的叶片损伤不仅低估了野外食草量，而且由于数据分析中无法控制的多种因素，它与自然界中发生的损伤水平不成比例。
