Community‐wide impacts of early season herbivory on flower visitors on tall goldenrod

Abstract

1. The flower visitor community consists not only of pollinators but also of non‐pollinators, such as florivores, thieves and predators that attack flower visitors. Although there is increasing evidence that early‐season foliar herbivory influences pollinator visitation through changes in floral traits, few studies have explored indirect effects of foliar herbivory on community structure of the flower visitors. We examined how early‐season foliar herbivory influences the flower visitor community established in late season. 2. We conducted an inoculation experiment using a lacebug (Corythucha marmorata), which is a predominantly herbivorous insect attacking leaves of tall goldenrod (Solidago altissima) in Japan. 3. Flower abundance significantly decreased when damaged by the lacebug. The numbers of pollinators, florivores and thieves were positively correlated with flower abundance, whereas predators were not. In response to flower abundance, florivores decreased on damaged plants. On the other hand, thieves increased on damaged plants, and pollinators and predators did not differ between damaged and undamaged plants. 4. When effects of flower abundance were excluded, foliar herbivory still influenced florivores negatively and thieves positively. This implies that factors besides flower abundance may have affected the numbers of florivores and thieves. 5. Community composition of flower visitors on damaged plants significantly differed from undamaged plants, although overall abundance, taxonomic richness and taxonomic evenness were unaffected by foliar herbivory in the early season. It is important to recognise that only evaluating species diversity and overall abundance may fail to detect the significant consequence of early‐season herbivory on the flower visitor community.

An exotic herbivore reinforces competition between exotic and native plants

“…These patterns indicate that direct competition and apparent competition caused by lace bug herbivory decreased the flower production of the focal plants in Japan after two growing seasons. Lace bugs have previously been reported to decrease flower production in S. altissima (Ikemoto et al., 2016; Sakata et al., 2014). Lace bug herbivory can severely damage the leaves, causing defoliation (Neal & Schaefer, 2000), and thus damage throughout the growing season in Shiga may have diminished the resources available for flower production.…”

A lack of genetically compatible mates constrains the spread of an invasive weed

“…Because S. altissima is an insect‐pollinated species, proximity to pollen sources should influence pollination success (Kunin, 1993; Agren, 1996). Generalist pollinators, including honeybees and syrphid flies, visit S. altissima in Japan (Ikemoto et al , 2017). While the average foraging distance of honeybees, for example, is < 2 km (Steffan‐Dewenter & Kuhn, 2003), the average distance between patches within Australia was > 10 km (Fig.…”

Bidirectional plant‐mediated interactions between rhizobacteria and shoot‐feeding herbivorous insects: a community ecology perspective

“…Moreover, two‐thirds of angiosperm plants interact with insect pollinators (Schoonhoven et al ., 2005; Bascompte & Jordano, 2007). Thus, plants are members of a diverse insect community consisting of species at different trophic levels (Stam et al ., 2014; Ikemoto et al ., 2017). This community is dynamic.…”