Native or Exotic? Double or Single? Evaluating Plants for Pollinator-friendly Gardens

Abstract

In a series of dawn-to-dusk studies, we examined the nature and accessibility of nectar rewards for pollinating insects by monitoring insect visits and the secretion rate and standing crop of nectar in the British native plant species Salvia pratensis , Stachys palustris , S. officinalis , Lythrum salicaria , Linaria vulgaris , the non-native Calendula officinalis , Petunia × hybrida , Salvia splendens , and the possibly introduced Saponaria officinalis . We also compared single with double variants of Lotus corniculatus , Saponaria officinalis , Petunia × hybrida and Calendula officinalis . All the British species studied are nectar-rich and are recommended for pollinator-friendly gardens. They showed maximal secretion rates of about 10–90 μg sugar per flower h −1 , and most had mean standing crops of about 5–60 μg sugar per flower. In all British species studied, the corolla was deep enough for the relatively long-tongued bumblebee Bombus pascuorum , but the shallower flowers of Lythrum salicaria were also much visited by shorter-tongued bees and hoverflies, as well as by butterflies. The exotic Salvia splendens , presumably coevolved with hummingbirds in the Neotropics, has such deep flowers that British bees cannot reach the nectar except by crawling down the corolla. With a secretion rate approaching 300 μg sugar per flower h −1 and little depletion by insects, S. splendens accumulated high standing crops of nectar. S. splendens , and single and double flowers of the two probably moth-pollinated species Petunia × hybrida and Saponaria officinalis , received few daytime visits despite abundant nectar but Calendula was well visited by hoverflies and bees. We compared single and double variants of Lotus corniculatus , Petunia × hybrida and Calendula officinalis , and also Saponaria officinalis , the last being probably introduced in Britain (Stace, 1997 New flora of the British Isles. 2nd edn. Cambridge: Cambridge University Press). In Petunia , Saponaria and Lotus , double flowers secreted little or no nectar. In Calendula , where doubling involved a change in the proportion of disc and ray florets rather than modification of individual flower structure, double and single capitula had similar standing crops of nectar. Except in Calendula , exotic or double flowers were little exploited by insect visitors. In the exotics, this was probably due to the absence or scarcity of coevolved pollinators, coupled, in double flowers, with the absence of nectar. Copyright 2001 Annals of Botany Company

Bumblebees in the city: abundance, species richness and diversity in two urban habitats

“…Frankie et al 2005), but not all types of plants (e.g. Comba et al 1999;Corbet et al 2001), and floral abundance can be a major factor affecting bees in urban environments (Matteson and Langellotto 2010). In a study of bees in urban habitats in Vancouver, British Columbia, Tommasi et al (2004) found that species richness of bees, including bumblebees, did not differ significantly between city gardens and traditional flowerbeds.…”

The biology of invasive alien plants in Canada. 9. Impatiens glandulifera Royle

“…(1 (Comba et al 1999a,b;Corbet et al 2001). When Chittka and Schu¨rkens (2001) introduced I. glandulifera plants to areas where native plants occurred in Germany they recorded a 50% reduction in pollinator visits to the native species Stachys palustris L. Furthermore, seed set was reduced by 25% in mixed patches as compared to pure patches containing only S. palustris (Chittka and Schu¨rkens 2001).…”

Composition and diversity of bees (Hymenoptera) attracted by Moericke traps in an agricultural area in Rio Claro, state of São Paulo, Brasil

“…Urban growth and expansion of agricultural area for food production are directly related to the reduction in populations of native bees and the disappearance of species recorded throughout the world, and the destruction of habitats is cited as the most important factor contributing to this decline, with the disappearance of nesting and foraging sites (CORBET et al, 2001;STEFFAN-DEWENTER et al, 2002).…”