The most effective pollinator revisited: pollen dynamics in a spring-flowering herb

Abstract

Most flowers are visited by a wide range of potential pollinators. However, their efficiency in pollen removal and deposition, and other behavioural factors affecting pollination effectiveness may greatly differ among taxa, and even individuals. Fritillary (Fritillaria meleagris L., Liliaceae) is a spring-flowering, critically endangered plant in the Polish flora, red-listed in most of the European countries of its range. Based on indirect evidence, that is, body pollen loads, visitation frequency and seasonal abundance, it is estimated that its key pollinators are queen bumblebees, but, as shown in the literature, the largest Fritillaria pollen loads are carried by solitary bees. To study pollinator effectiveness for floral visitors to F. meleagris, we performed a garden experiment, where we analysed pollen deposition and assessed pollen removal per single flowervisit in the plant. Similarly to field conditions reported in the literature, our experimental plants were serviced by nectarseeking bumblebee queens and two taxa of solitary bees, small pollen-collecting Andrena and large, nectar-seeking Anthophora males. When ''quality'' component was addressed, despite the character of visits, insects from all groups deposited more pollen than was found on unvisited flowers, but they did not differ significantly from each other in pollen deposition on virgin stigmas. We also found some differences in pollen removal both within-and among-visitor species and control flowers, unfortunately due to extremely high variation of the results they were all statistically insignificant. However, when ''quantity'' component of insect performance was concerned, we observed that over 81 % of visits were by bumblebees. Bombus queens stayed on flowers significantly less time than small Andrena individuals (13 % of recorded visits) and equally long as Anthophora males (only 6 % of visits). We conclude that although all the visitor groups can pollinate the flowers of F. meleagris, bumblebee queens indeed proved to be the most effective pollinators of the plant, when both quality and quantity components of pollination are concerned.

Myophily in the critically endangered umbelliferous plant Ostericum palustre Besser (Apiaceae)

“…This shows that the hypothesis proposed by some researchers (Gómez and Zamora 1992;Morris 2003;Vázquez et al 2005), namely, that visit rate is a good surrogate of pollinator performance, should be treated with caution, as it is true only for some plant species (see e.g. Motten et al 1981;Fishbein and Venable 1996;Olsen 1997;Sahli and Conner 2007;Niemirski and Zych 2011;Zych and Stpiczyńska 2012;Zych et al 2013), and thus may be misleading in others (e.g. Zych 2002Zych , 2007Fumero-Cabán and Watts et al 2012; and the present study).…”

Flower-visitor and pollen transport networks in a large city: structure and properties

“…In our systems, the proportion of taxa that carried no pollen whatsoever was relatively small, 4 and 13 %, respectively, for Ochota and Kabaty, but this number may be higher for other ecosystems (Forup and Memmott 2005;Alarcon 2010). Body pollen loads are one of the necessary prerequisites of pollination (Johnson and Steiner 2000;Pellmyr 2002), but they still do not provide much information on the real importance of visitor taxa (see e.g., Zych et al 2013) and hence do not offer the ultimate solution to our efforts of studying real pollination networks, as opposed to flower-visitor networks. Pollen transport networks seem, however, an important step towards better understanding the complex relationships that exist between plants and their pollinators on an ecosystemic scale (Popic et al 2013).…”

Effect of forest clear cuts on plant–pollinator interactions: the case of three ericaceous subshrubs in Lithuanian pine forests

“…Ants were earlier recorded as floral visitors in flowers of V. myrtillus [25] and C. vulgaris [7], but treated as nectar thieves rather than efficient pollinators. In both studies, however, no measure of insect effectiveness (see, e.g., [38] for details) was applied. Ants are an important element of boreal forest ecosystems [39], and despite their low efficiency in flowers, some authors suggest that potentially they could be important in pollination of species with easily accessible flowers producing little nectar and occurring in high local densities [40], a characteristic fitting many forest Ericaceae.…”