Wasps Beyond Bees: Crop Species of Spondias (Anacardiaceae) Vary in Floral Scent and Attract Different Pollinator Taxa

Abstract

Spondias species are increasingly valued for their fruit production, which relies heavily on insect pollination. The flowers of these species are generalised, attracting a diverse array of insect visitors, including bees, beetles, flies, wasps and butterflies. This study provides the first comprehensive analysis of floral scents emitted by three Spondias crop species—Spondias mombin (cajá), S. purpurea (siriguela) and S. tuberosa (umbu) and explores the potential relationships between floral cues and pollinator spectra. We examine the spectrum of floral visitors across these species from both literature and original field observations. Our results reveal significant interspecific differences in both the number and quantity of volatile compounds released, as well as in the relative composition of these scents. Cajá flowers were dominated by (E)-β-ocimene, α- and β-pinene, methyl benzoate and benzyl alcohol, whereas siriguela flowers primarily emitted (E)-β-caryophyllene, (E)-4,8-dimethyl-1,3,7-nonatriene, α-pinene, hexyl butyrate, methoxybenzene and 4-methylanisol. Umbu flowers predominantly emitted linalool and its derivatives, and (Z)-3-hexenyl butyrate. The floral visitor composition varied between species. Bees, particularly from the Meliponini tribe, were the main visitors of cajá (70%), whereas siriguela attracted primarily wasps (80%), especially from the Epiponini tribe. Umbu flowers attracted in similar proportions both wasps (38%) and bees (32%). These findings highlight the importance of a broad range of insect pollinators in Spondias species, particularly the role of non-bee pollinators like social wasps in the pollination of siriguela and umbu. We propose that variations in floral scent profiles and visual cues among these species are key factors in shaping their specific pollinator communities. This underscores the critical role of diverse insect pollinators in maintaining ecosystem services, reinforcing the need to preserve and support their populations.