Labellar Structure of the Maxillaria splendens Alliance (Orchidaceae: Maxillariinae) Indicates Floral Polyphenols as a Reward for Stingless Bees

Abstract

Several studies have reported stingless Meliponini bees gathering hairs from the labella of Maxillaria spp., including M. ochroleuca, a member of the M. splendens alliance. Such hairs usually contain food materials and are thought to have nutritional value. The papillose labella of representatives of the Maxillaria splendens alliance, however, bear scattered, simple 1-5-celled uniseriate trichomes (hairs) that lack food materials. By contrast, here, as well as polyphenolic compounds, typical labellar papillae usually contain small quantities of starch, protein, and minute droplets of lipid, the last probably involved in the production of fragrance. Towards the labellum apex occur elevated groups of papillae that lack food materials, but contain volatile compounds, probably fragrance precursors. In the past, the terms ‘trichomes’ or ‘hairs’ and ‘papillae’ have been used interchangeably, causing some confusion. Since the trichomes, however, unlike the papillae, are easily detachable and can fragment, it is most likely they, not the papillae, that have previously been observed being collected by bees, but their poor food content indicates that they do not function as food-hairs. Even so, our field observations of M. ochroleuca reveal that stingless bees scrape polyphenol-rich labellar tissue and possibly use this material to produce a resinous, complex, heterogeneous substance commonly referred to as ‘bee glue’, used for nest construction and repair.

Nectar‐mediated avian pollination in Cattleya (Orchidaceae: Laeliinae)

“…As pointed out in , generalizations about the offering of floral resources in certain groups of orchids needs to be revised because many pollination systems assumed to be food-deceptive are actually mediated by the production of some kind of resource used by pollinators. Indeed, the production of floral rewards was recently described for orchids previously considered to be pollinated by both generalized food-deception (e.g., Brasiliorchis, Vanilla and Maxillaria; Pansarin 2022;Davies et al 2023) and Batesian mimicry (e.g., Gomesa; . Here, the discovery of a reward-producing species (C. cernua) within a genus entirely pollinated by strategies of food-deception (Cattleya) provides clues and new insights into the understanding of the diversification of Laeliinae across the Neotropics.…”

“…2022; Pansarin 2022; Davies et al . 2023) and Batesian mimicry ( e.g ., Gomesa ; Pansarin et al . 2017).…”