Patterns of change in floral color and odor of Lonicera calcarata are in relation to pollinator behavior

Abstract

Floral color and odor serve as attractants for pollinators. It remains unclear how changes in these traits in color-change species interact with pollinators and impact a plant's reproductive success. Lonicera calcarata flowers change from white (Night 1 [N1] and Day 1 [D1]) through yellow (Night 2 [N2]) and orange (Day 2 [D2]) to orange-red (Night 3 [N3] and Day 3 [D3]). Our research showed that floral characters, stigma activity, nectar production and floral spectral reflectance decreased through the flowering phases. Floral odor mainly comprised fatty acids, aldehydes, monoterpenes and alcohols, especially n-hexadecanoic acid, hexadecanal and 3-carene. Floral odor peaked on N1 and N3, largely due to the presence of fatty acids. The emission of n-hexadecanoic acid was higher on N1 and N3 compared with other phases, while hexadecanal emission remained constant throughout the flowering stages. The emission of 3-carene was highest on N1. Lonicera calcarata was mainly pollinated by the moth Chorodna strixaria, the butterfly Acosmeryx naga and three bumblebees (Bombus melanurus, B. eximius, B. sonani) and they all preferred to visit white (younger) flowers. Moths had a preference for 3-carene and no significant preference for n-hexadecanoic acid and hexadecanal. Seed sets of nocturnal pollination and control treatments were not significantly different. Lonicera calcarata could produce seeds by self-pollination; cross-pollination significantly increased the seed set. Floral color guides pollinators to visit younger flowers with more floral rewards and higher stigma activity. Different chemical compounds in floral odor may not only attract pollinators but also avoid herbivore damage.

Keywords

flower color / flower scent / Lonicera calcarata / plant strategy

RIGHTS & PERMISSIONS

2025 Institute of Botany, Chinese Academy of Sciences.