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

Abstract

Social vespid wasps regularly forage on flowers with a generalist pollination system. However, little is known about communication between wasps and their host plants. The aim of this study was to investigate the role of olfactory and visual floral signals of Hedera helix and Heracleum sphondylium, both frequently visited by Vespula and Dolichovespula wasps for the collection of nectar. A combination of chemical, electrophysiological and spectral analyses and behavioral experiments was used to identify attractive floral signals. We identified 37 and 41 EAD-active substances (mainly terpenoids and aromatics) in H. helix and H. sphondylium, respectively. The most abundant floral compounds were 4-oxoisophorone in H. helix and linalool in H. sphondylium, followed by (E)-linalool oxide furanoid in both plants. The olfactory signals were attractive for wasps; however, a combination of olfactory and visual signals made both plants more attractive than olfactory signals alone and, in the case of H. helix, also than visual traits alone. Visual traits were not attractive by themselves. Wasps were also attracted by a synthetic solution resembling the floral scent of H. helix.Our study contributes to a better understanding of the foraging behavior of vespid wasps and describes, for the first-time, floral signals that attract vespine wasps to generalist flowers.

Insect trash is a plant’s treasure: effects of insect exuviae as soil amendment on pollinator performance and plant reproduction

“…terfly Pieris brassicae exhibited a strong bias for optical cues over volatile chemical cues when both cues were offered separately, in agreement with studies on host location by insect pollinators, in which many pollinators exhibit feeding behaviour in response to colour stimuli (Van der Kooi et al, 2021). In contrast, other studies have reported that chemical cues are more important than optical cues to attract pollinators from a distance (Raguso, 2008;Primante and Dötterl, 2010;Lukas et al, 2020). However, insect pollinators exploit visual and odour information simultaneously, thus optical and chemical plant traits both contribute to foraging pollinator preferences (Raguso and Willis, 2002;Milet-Pinheiro et al, 2012;Chapter 2).…”

Neural and behavioural responses of the pollen-specialist beeAndrena vagatoSalixodours

“…However, there are recent studies that describe 4-oxoisophorone as floral scent component in a broader range of species (e.g. El-Sayed et al, 2018;Lukas et al, 2019Lukas et al, , 2020. Future studies should test how A. vaga bees behaviourally respond to 1,4-dimethoxybenzene and 4-oxoisophorone when they are offered simultaneously, and to which extent these two compounds may be synergistically involved in host recognition.…”

Chemistry, biosynthesis and biology of floral volatiles: roles in pollination and other functions

“…In three highbush blueberry (Vaccinium corymbosum) cultivars, oral scents are dominated by (E)-cinnamyl alcohol ( 154), but various aliphatic compounds and terpenes also are released. 312 Finally, one study tested for correlations between oral volatiles of greenhouse tomato (Lycopersicon esculentum, Solanaceae) and pollination by bumblebees. 313 Tomato owers released b-phellandrene (201), 2-carene ( 202), a-pinene (72) and p-cymene (106), and bumblebees preferably pollinated owers that produced less 201 and 202 than owers producing more of these compounds.…”

“…, ( E )-β-ocimene ( 62 ), 4-oxoisophorone ( 169 )], but also rare [ N -isobutylformamide ( 199 ), ( E )- N -(3-methylbutyl)-1-phenylmethanimine ( 200 )] floral scents and even compounds newly identified from nature [( E )- N -(2-methylbutyl)- and ( E )- N -(3-methylbutyl)-1-(pyridin-3-yl)methanimine ( 46 and 47 )]. 312 …”

“…Brodmann et al332 studied the olfactory attractiveness of Scrophularia umbrosa (Scrophulariaceae) host plants to social Vespula vulgaris wasps and found that only a blend of312 For H. helix experiments with synthetic compounds were also performed and it was found that a synthetic mixture resembling the oral scent of this species was attractive to the wasps, but less than the natural olfactory cues. Besides social Vespula wasps, advances were made in the host nding of solitary g wasps, which are involved in the highly specialized brood-site mutualisms with gs, and in generalist parasitoids.…”