The sweet smell of success: floral scent affects pollinator attraction and seed fitness in Hesperis matronalis

Abstract

Summary 1.Patterns of floral scent are generally assumed to have been shaped by pollinator-mediated natural selection. However, while many studies document behavioural responses of pollinators to floral scent, few document the relationship between floral scent and fitness. 2. In this study, we explore the effect of variation in floral scent emission in colour polymorphic Hesperis matronalis on both pollinator visitation and seed fitness. 3. Using target inflorescences augmented with colour-specific floral scent extracts, we find that diurnal floral visitors significantly prefer night-scent extracts to non-augmented controls; inflorescences augmented with day-scent extracts receive an intermediate level of visits. Colour did not have a significant effect on visitation. 4. We characterized the relationship between natural variation in floral scent emission rate and seed production for plants under two settings: in small experimental arrays exposed to either dayor night-flying pollinators, and in wild populations exposed to all pollinators. In arrays, we found greater emission rate led to higher seed production, but only in plants exposed to day-flying pollinators. In contrast, we found a significant positive relationship between night-time floral emission rate and seed fitness in wild populations. In neither setting did floral anthocycanin concentration (colour) affect fitness. 5. This study reinforces the idea that scent-mediated pollinator visitation is an important component of plant fitness. Moreover, our results suggest that plants emitting more scent have higher fitness, although there is variation as to when this positive relationship occurs (i.e., at day or night). Research connecting floral scent and fitness is a necessary first step in understanding the evolution of floral scent.

Influence of Honey Bee,Apis mellifera, Hives and Field Size on Foraging Activity of Native Bee Species in Pumpkin Fields

“…Empirical studies have shown that phenotypic and genetic variation in nectar traits can have signiÞcant direct and indirect impacts on pollination success (Galen and Newport 1988, Mitchell 2004, Salzmann et al 2007, Majetic et al 2009). In our study, pistillate ßowers produced signiÞcantly more nectar than staminate ßowers.…”

Experimental manipulation of floral scent bouquets restructures flower–visitor interactions in the field

“…For the preparation of flower extracts, freshly picked flower heads/corymbs were weighed and transferred into pentane (10 mL g À1 fresh weight) as described in Majetic, Raguso & Ashman (2009). The glass container was sealed with parafilm and stored for 20 min at 4°C.…”

How can an understanding of plant–pollinator interactions contribute to global food security?

“…Recent experiments with volatile cues have highlighted the complexity of their function. Experimentally augmenting floral scent increased pollinator attraction for Hesperis matronalis [46], but only with specific components of its floral bouquet. In contrast, a similar experiment with Curcurbita pepo had no effect on pollinators but increased visits from florivores [47].…”