Tools to Tie: Flower Characteristics, VOC Emission Profile, and Glandular Trichomes of Two Mexican Salvia Species to Attract Bees

Abstract

A plant can combine physical and chemical tools to interact with other organisms. Some are designed for pollinator attraction (i.e., colors and volatile organic compounds-VOCs); others can act to discourage herbivores (i.e., non-glandular trichomes). Few studies fully address available tools in a single species; notwithstanding, this information can be pivotal in understanding new interactions out of the home range. We characterized flower traits, emission profiles of constitutive compounds from flowers and leaves, micro-morphology of the glandular trichomes, and listed flower visitors of two Mexican bird-pollinated Salvia species (S. blepharophylla and S. greggii), growing in an Italian botanical garden. Flowers were highly variable in their morphometric characteristics. In both species, four trichome morphotypes with similar histochemistry and distribution were documented for leaves and flowers except the calyx abaxial side. The vegetative emission profiles were qualitatively more complex than the floral ones; however, common compounds occurring in high relative percentages were β-caryophyllene and germacrene D. Floral bouquets were dominated by limonene and β-pinene in S. greggii and by 1,8-cineole in S. blepharophylla. Two potential (non-bird) pollinators were especially abundant: small bees belonging to the genus Lasioglossum and large bees belonging to the species Xylocopa violacea. Our study highlights the plasticity of these plants, as well as tools that can be conveniently used to establish novel interactions.

Morphology and phytochemistry of Teucrium chamaedrys L. (Lamiaceae) cultivated at the Ghirardi Botanic Garden (Lombardy, Northern Italy)

“…β-Caryophyllene (34) could be involved in the preselection and attraction of pollinators (Giuliani et al, 2020c;Novaković et al, 2019). Specifically, its emission from flowers could stimulate positive feedback in honeybees as Apis cerana (Abraham et al, 2018) and A. mellifera (Giuliani et al, 2020e), as well as in non-pollinators as Vespa velutina and Bombus spp. (Giuliani et al, 2021;Zhang, 2018).…”

Botanic Garden as a Factory of Molecules: Myrtus communis L. subsp. communis as a Case Study

“…However, it is also an attractant for common large wood-boring beetles from southeastern USA, being used in traps to detect and monitor these pests in forested areas [35]. 1,8-Cineole (15) shows anti-bacterial activity [36] and a powerful toxicity against important wheat pests [37]; however, it is also recognized as an attractant of different bee pollinators [38,39]. Linalool ( 20) is documented to intoxicate and repel herbivores [40] and possess antibacterial and antifungal activity [41]: however, it also attracts the males of Ceratitis capitata, one of the most economically important fruit fly pests [42].…”

Overview of Bee Pollination and Its Economic Value for Crop Production

“…Indeed, higher numbers of bees occur on the moving portion of a flower bed due to their positive response to optical stimulation [139]. In addition, floral volatile compounds affect the orientation of bees [141], as well as pollen collection and behavior in bumble bees [142]. Flower size has a special function for attracting pollinators [141]; bumble bees (Bombus diversus Smith) prefer large floral displays [143].…”

“…In addition, floral volatile compounds affect the orientation of bees [141], as well as pollen collection and behavior in bumble bees [142]. Flower size has a special function for attracting pollinators [141]; bumble bees (Bombus diversus Smith) prefer large floral displays [143]. some flies also use vibration behavior to collect pollen.…”