Diverse visitors with various pollinator importance and temporal change in the important pollinators of Geranium thunbergii (Geraniaceae)

Abstract

Assessing pollinator importance of each floral visitor to a plant species is a key to understanding plant–pollinator interaction. The present study examined visitation frequency, pollination efficiency, and pollinator importance of the full range of floral visitors to Geranium thunbergii natural population, by measuring seed‐set. During 2 years of observations, the flowers were visited by at least 45 insect species belonging to four orders. Among the main 22 visitor species, 11 species belonging to three orders (Hymenoptera, Diptera, and Lepidoptera) acted as the efficient pollinators. In both years, Hymenoptera, especially bees, was the most important pollinator to G. thunbergii. Thus, the flowers could be considered as bee‐pollinated. However, the most important species were not constant between years. The study also documented that the efficient pollinators have larger body sizes. The dish‐shaped floral morphology, taxonomically diverse pollinators, and temporal change in the most important pollinators indicate that G. thunbergii–pollinator interaction is a rather generalized system. The results suggest that casual observations of visitation, or even precise measurement of pollinator importance in a single season is insufficient to identify important pollinators.

Prolonged stigma and flower lifespan in females of the gynodioecious plant Geranium sylvaticum

“…Whether senescence is induced in G. sylvaticum by pollination is unknown, but it is likely as it has been described or suggested for other species in this genus like G. pyrenaicum (Fitting, 1911), G. pusillum (Schulz, 1902) and G. maculatum (Van Etten and Chang, 2014). Also, G. thunbergii hermaphrodite flowers that were artificially or naturally pollinated flowered on average about one day shorter than unpollinated hermaphrodite flowers (Kandori, 2002).…”

“…Varga and Kytöviita (2010) observed that experimental hermaphrodite plants were visited 1.5 times as much as females during 30 minutes trials. However, when bumblebee visits (23% of all visits), which are potentially the most important pollinator group of Geranium (Kandori, 2002) were analyzed separately, no clear preference for either sex was detected. Higher visitation rates for hermaphrodites have been reported also in other Geranium species (Table 1).…”

Bumble Bee Abundance in New York City Community Gardens: Implications for Urban Agriculture

“…Leaf-cutter bees are medium-sized bees that carry pollen on the ventral side of their abdomen, thereby easily transmitting pollen to female flowers. Small-bodied bees (Lasioglossum, Hylaeus, Ceratina) also were abundant in these gardens (Matteson et al 2008) and New York City parks (Yurlina 1998) but may be less efficient pollinators on a per visit basis because they carry less pollen and are less likely to come into contact with anthers and/or stigmas (Kandori 2002). Hylaeus spp.…”

Biodiversity, Species Interactions and Ecological Networks in a Fragmented World

“…seasonality of occurrence), phylogeny (similar roles of closely related species) and place of origin (e.g. native vs. exotic), which can influence pollination rates and species interactions (Fishbein and Venable, 1996;Kandori, 2002;Raine and Chittka, 2005), or whole pollination networks (Lopezaraiza-Mikel et al, 2007). Still remarkably little is known about how relative abundance affects within-functional group competition for the same resources at the network level.…”