Cephalaria transsylvanica-Based Flower Strips as Potential Food Source for Bees during Dry Periods in European Mediterranean Basin Countries

Abstract

The introduction of sown wildflower strips favours the establishment of pollinator communities, with special reference to social Apoidea. Here, we evaluated the late summer flowering Cephalaria transsylvanica as suitable species for strips providing food for pollinators in paucity periods. C. transsylvanica showed no particular requirements in terms of seed germination and growth during summer. This plant had an excellent potential of self-seeding and competitiveness towards weed competitors. C. transsylvanica prevented from entomophilous pollination showed inbreeding depression, with a decrease in seed-set and accumulation of seed energy reserves. However, C. transsylvanica did not appear to be vulnerable in terms of pollination biology since it had a wide range of pollinators including bees, hoverflies and Lepidoptera. C. transsylvanica was visited mainly by honeybees and bumblebees and these latter pollinators increased their visits on C. transsylvanica flowers during early autumn. This plant may be useful as an abundant source of pollen during food paucity periods, such as autumn. We proposed C. transsylvanica for incorporation into flower strips to be planted in non-cropped farmlands in intensively managed agricultural areas as well as in proximity of beehives. The latter option may facilitate the honeybees collecting pollen and nectar for the colony, thereby ensuring robustness to overcome the winter season.

Weed-insect pollinator networks as bio-indicators of ecological sustainability in agriculture. A review

“…The growing need to maintain and/or restore arable land biodiversity meant that we have focused on weed species that are becoming rare due to their dependence on pollinators (Paoletti 1995). Moreover, many insect pollinators are threatened by an increasing risk of extinction due to the gradual decrease in nectariferous plants that are food sources for adults, as well as by the decline of host plants that are essential for oviposition and larval development (e.g., butterflies species) (Kremen et al 2007;Nicholls and Altieri 2012;Benelli et al 2014).…”

“…For instance, species of the Caryophyllaceae family are often characterized by rigid mutualistic interactions that are initiated by Lepidoptera (Kephart 2006). This type of interaction is fragile, since many Lepidoptera and other pollinators depend on the plants in two ways: they require flowers with nectaries as a food source and certain host plants for oviposition and feeding of larval forms (Kremen et al 2007;Nicholls and Altieri 2012;Benelli et al 2014). Butterfly species frequently depend on restricted plant groups, often belonging to a single botanical family, a single genus or even a single species.…”

“…Although weeds with brightly colored flowers are frequently visited by insects, even species with duller flowers can provide key food floral sources, especially when few other plants are in flower (e.g., early spring) (Levin and Anderson 1970;Petanidou and Vokou 1993;Dafni 1996;Odoux et al 2012;Rollin et al 2013;Benelli et al 2014;Canale et al 2014;Requier et al 2014). In late summer, insect pollinators can be observed on the most common weed species in seminatural habitats, such as many Asteraceae (e.g., Aster squamatus (Sprengel) Hieron, Conyza canadensis (L.) Cronq., Senecio vulgaris L., Sonchus spp., and Xanthium (Rollin 2013 (Westwood et al 1997), and D. stramonium L. (Solanaceae) (Motten and Antonovics 1992).…”

Long lasting summer flowerings of Lythrum salicaria as honeybee-friendly flower spots in Mediterranean basin agricultural wetlands

“…For each strip, ten L. salicaria plants have been randomly selected and marked, and used both for evaluation of flowering-dynamics and pollinators' abundance. L. salicaria flowering dynamics was surveyed following the methods reported in Benelli et al (2014). From June to September 2014, samplings were carried out every ten days (three replicates for each sampling) and the number of open flowers per plant was noted.…”

“…Such areas offer a suitable environment for soil-nesting bee pollinators, as well as for Lepidoptera species that require particular plant species on which to oviposit (Saarinen, 2002;Nicholls and Altieri, 2013;Rollin et al, 2016). Since abundance and diversity of wild and managed bees is strictly related to the availability of continuous floral resources (Wratten et al, 2012), the establishment of flower-rich plant communities within or around intensively farmed landscapes increases the availability of pollen and nectar resources supporting Apoidea populations (Carvell et al, 2007;Decourtye et al, 2010;Haaland et al, 2011;Fabian et al, 2013;Benelli et al, 2014).…”