Dung mimicry: the function of volatile emissions and corolla patterning in fly‐pollinated Wurmbea flowers

Abstract

Summary It has been suggested that flowers of some angiosperms mimic vertebrate faeces (dung) in order to exploit insect pollinators that utilize faeces as a source of food and/or oviposition sites. We investigated a potential case of mimicry in Wurmbea elatior (Colchicaceae), a lily that exhibits a faecal odour and pattern of dark spots on the corolla. We found that W. elatior is pollinated by a broad assemblage of coprophagous flies and is dependent on pollinator visits for seed production. The flowers emit volatiles that are characteristic of vertebrate faeces, and three of these compounds – skatole, indole, and an unidentified compound – elicited electrophysiological antennal responses from flies. Artificial flowers laced with indole and skatole or skatole alone attracted the same assemblage of flies as was recorded on flowers of W. elatior. Spotted artificial flowers attracted twice as many flies as did those lacking spots. Experimental addition of indole and skatole to flowers of Wurmbea kraussii, a congener with unscented flowers pollinated by hoverflies, induced a shift to an insect visitor assemblage dominated by coprophagous flies. This study clarifies the roles of volatile emissions (particularly skatole) and visual signals in floral dung mimicry.

Olfactory and Visual Floral Signals of Hedera helix and Heracleum sphondylium Involved in Host Finding by Nectar-Foraging Social Wasps

“…Instead, we conclude, that wasps seem to be attracted to the studied plants by floral scent compounds that are also physiologically and/or behaviorally active for other flower visitors, such as bees, moths, butterflies, and flies (Andersson, 2003;Dötterl and Vereecken, 2010;Johnson et al, 2020;The Pherobase, 2020). The release of such compounds might be the reason that H. helix and H. sphondylium are attractive to insects of various orders and families.…”

“…Some EAD-active compounds of H. sphondylium are less common among the floral scents, especially the nitrogen-bearing 2-aminoacetophenone and its likely derivate m/z 120, 135, 92, 65, 163, 93 (Johnson et al, 2020). 2-Aminoacetophenone has been shown to attract various flies to bacteria (Kapsetaki et al, 2014), and its likely derivative is EADactive in the scent of fly-pollinated Wurmbea flowers, a lily that exhibits a fecal odor (Johnson et al, 2020). Moreover, the scent of H. sphondylium is reminiscent of the smell of dung, possibly because of the presence of p-cresol.…”

‘Bleeding’ flowers of Ceropegia gerrardii (Apocynaceae‐Asclepiadoideae) mimic wounded insects to attract kleptoparasitic fly pollinators

“…It is fairly common for fly‐deceiving flowers to offer food rewards. For example, nectar is present in the sexually deceptive flowers of Gorteria diffusa (Ellis & Johnson, 2010) and in some dung‐ or carrion‐mimicking flowers (Shuttleworth et al ., 2017; Johnson et al ., 2020). In these systems, the mimetic floral signals are irresistible to the flies and the role of the nectar is to manipulate the flies' behaviour to maximize the probability of pollen transfer.…”

Floral Scent Evolution in the Genus Jaborosa (Solanaceae): Influence of Ecological and Environmental Factors

“…revealed that variation in flower size and oligosulfide concentration was associated with niche partitioning between sarcophagid and calliphorid flies, which appear to specialize in dead animals of different sizes [ 90 ]. Subsequent studies in the same region revealed that flies attracted by scent are filtered as pollinators by non-chemical traits that either restrict access by size (floral guardrails [ 91 ]) or encourage landing by simulating the presence of other flies (tepal spots [ 92 ]).…”