Evaluation of Selected Ornamental Asteraceae as a Pollen Source for Urban Bees

Abstract

A b s t r a c t Offering more floral resources for urban bees can be achieved by growing ornamental bee plants. The aim of the present study was to evaluate selected Asteraceae (Calendula officinalis 'Persimmon Beauty' and 'Santana', Centaurea macrocephala, Cosmos sulphureus, Dahlia pinnata, Tagetes patula, Tithonia rotundifolia, and Zinnia elegans) as pollen sources for pollinators. Under urban conditions in Lublin, SE Poland, the investigated plants flowered from late June to the end of October. The mass of pollen produced in florets and capitula was found to be species-related. The highest pollen amounts per 10 florets (10.1 mg) as well as per capitulum (249.7 mg) were found for C. macrocephala. The mass of pollen yielded by a single plant depended on both the pollen mass delivered per disk florets and the proportion of disk florets in capitulum, and the flowering abundance of the plants. A single plant of D. pinnata and a single plant of T. rotundifolia each produced the largest pollen mass. Mean pollen yield per 1m 2 of a plot ranged from 6.2 g (Z. elegans) to 60.7 g (D. pinnata). Pollen grains are tricolporate, with echinate exine, medium or small in size. They can be categorised as oblatespherical, spherical, and prolatespherical. The principal visitors to C. macrocephala, C. sulphureus, and C. officinalis were honey bees, whereas bumble bees dominated on T. rotundifolia and D. pinnata. A magnet plant for butterflies was Z. elegans. Among the investigated species, D. pinnata, C. macrocephala, and T. rotundifolia were found to be the most valuable sources of pollen flow for managed and wild bees.

Diversity of Natural Enemies Associated with Refuge Flowering Plants of Zinnia elegans, Cosmos sulphureus, and Tagetes erecta in Rice Ecosystem

“…T. erecta has the largest pollen size (39 μm) compared to the two other flowers (Mazari et al, 2012). Z. elegans has a smaller pollen size (14.05 μm) than C. sulphureus (32.63 μm) (Wróblewska, 2016). Erdtman (1943) stated that the pollen fell in the small category if it has a size ranging from 10-25 µm and medium-size if ranging from 25-50 µm.…”

Pollination efficiency of Apis mellifera (Hymenoptera: Apidae) on Cosmos sulphureus (Asteraceae) capitula at Dang (Ngaoundéré, Cameroon)

“…3,9]. In spite of the preliminary studies of Tchuenguem et al [9] in Cameroon and Wróblewska et al in Poland [10] showing that A. mellifera visits C. sulphureus, there are no published data to our knowledge on the pollination efficiency of A. mellifera on C. sulphureus. In this same country, the demand for seeds of C. sulphureus, honey and pollen is high, while their production is low [11].…”

Characteristics of blooming, pollen production, and insect visitors of Polemonium caeruleum L. – a species with a potential to enrich pollinator-friendly urban habitats

“…Towns and cities have a mosaic structure of landscape which is regarded as beneficial for pollinating insects [27,28]. Urban recreational green areas (e.g., parks, private gardens, green roofs) contribute to the diversity of floral food resources for pollinators [29][30][31][32]. Nectariferous and polleniferous flora also occurs in ruderal sites [33], road verges [26,34], and along railway embankments [35].…”

“…In modern urban landscape design, a trade-off between aesthetic value and ecosystem services of plant species is desired. Ornamental plants can provide insect pollinators with considerable amounts of pollen and nectar sugars [29,31,38]. However, some ornamental plants are unattractive to native pollinators or they produce a very small amount of forage for the pollinators [39,40].…”

“…However, some ornamental plants are unattractive to native pollinators or they produce a very small amount of forage for the pollinators [39,40]. For the improvement of bee pastures, detailed data on blooming biology as well as on nectar and pollen quantity and quality is necessary in order to select the plant species most valuable for this purpose [29,38,41].…”