Nectar traits and their responses to herbivory in <scp> <i>Solidago altissima</i> </scp> as a dominant introduced flowering herb in Japan

Abstract This study investigates the nectar characteristics of the tall goldenrod ( Solidago altissima L.), an introduced dominant fall‐flowering herb in Japan. We found that the nectar volume of S. altissima peaked at approximately 13:00 before decreasing. Glucose and fructose were identified as the primary sugar components, followed by sucrose. The average sugar amount per panicle of naturally growing plants was estimated as 229.0 mg. Herbivory by the exotic lacebug ( Corythucha marmorata ) reduced the nectar volume per floret but did not affect the total sugar amount per floret. However, the sugar amount per panicle decreased substantially because C. marmorata reduced both the number of disc florets (i.e., nectar‐secreting florets) per head and the number of heads per panicle. Plant genotypes also influenced some nectar traits, interacting with the effects of herbivory. As the distribution of C. marmorata continues to expand across Japan, the nectar resources provided by S. altissima may be diminishing nationwide.