Evaluation of Deutzia x carnea (Lem.) Rehd. as a food source to urban bees

Marzena Masierowska

doi:10.5586/aa.2012.019

Abstract

This 3-year study examined the flowering phenology, to- tal floral display, nectar and pollen production as well as bee visitation to the ornamental shrub Deutzia x carnea (Lem.) Rehd. D. x carnea bloomed from early June until the middle of July. The total flower display reached 47927 flowers per plant. The number of developed flowers strongly depended on weather conditions before and during the flowering period and fluctuated significantly during the years of study. The flower of D. x carnea lived 5 days and the persistence of an inflorescence was 11 days. Nectar productivity per 10 flowers differed significantly between the years of study and ranged between 15.7 and 40.14 mg. Mean sugar content in nectar was 39.7%. The total sugar mass in nectar per 10 flowers averaged 9.91 mg (range: 3.81 – 18.91 mg). Pollen mass per 10 flowers was 16.89 mg. The estimated sugar and pollen productivity per plant was 36.8 g and 40 g, respectively. Among bees (Apoidea), honey bees were principal visitors on Deutzia flowers. The peak of daily activity of honey bees and bumblebees occurred between 11.00 and 15.00 hrs, whereas the presence of other wild bees was noted in the morning and in the late afternoon. All bees gathered mainly nectar, but pollen collectors were also noted. The mean daily visiting rate was 0.0809 visits per flower × min-1. The use of this shrub in gardens and parks should be encouraged in order to enrich food pasture for urban Apoidea. However, its cultivation is limited to areas of mild climate and adequate water supply.

Highlights

Bees are important plant pollinators, both in the natural environment and in anthropogenic habitats, e.g. cultivated crops or urban sites
Plant species richness often increases in urban areas compared to more natural habitats (Grimm et al 2008), so urban sites are thought to be potential resources for nectar- and pollen-foraging insects (A c a r et al 2007; Denisow, 2011)
The present study was conducted on four individuals of Deutzia x carnea growing on a loess-derived soil in the Botanical Garden of the Maria Skłodowska-Curie University, Lublin, Poland (N – 51o09’, E – 22o27’)

Summary

Introduction

Bees are important plant pollinators, both in the natural environment and in anthropogenic habitats, e.g. cultivated crops or urban sites. Plant species richness often increases in urban areas compared to more natural habitats (Grimm et al 2008), so urban sites are thought to be potential resources for nectar- and pollen-foraging insects (A c a r et al 2007; Denisow , 2011). The newly-planted urban parks and gardens are more often designated for bees and have potential to attract these insects if diverse floral resources are provided throughout the growing season (Comba et al 1999; Tommasi et al 2004; Dijkstra and K w a k , 2007; Wojcik et al 2008; Sperling and Lortie , 2010).

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