The Effects of Ozone on Visual Attraction Traits of Erodium paularense (Geraniaceae) Flowers: Modelled Perception by Insect Pollinators.

Samuel Prieto-Benítez,Ignacio Gonzalez-Fernandez,Victoria Bermejo-Bermejo,Raquel Ruiz-Checa

doi:10.3390/plants10122750

Abstract

Ozone (O3) effects on the visual attraction traits (color, perception and area) of petals are described for Erodium paularense, an endangered plant species. Plants were exposed to three O3 treatments: charcoal-filtered air (CFA), ambient (NFA) and ambient + 40 nL L−1 O3 (FU+) in open-top chambers. Changes in color were measured by spectral reflectance, from which the anthocyanin reflectance index (ARI) was calculated. Petal spectral reflectance was mapped onto color spaces of bees, flies and butterflies for studying color changes as perceived by different pollinator guilds. Ozone-induced increases in petal reflectance and a rise in ARI under NFA were observed. Ambient O3 levels also induced a partial change in the color perception of flies, with the number of petals seen as blue increasing to 53% compared to only 24% in CFA. Butterflies also showed the ability to partially perceive petal color changes, differentiating some CFA petals from NFA and FU+ petals through changes in the excitation of the UV photoreceptor. Importantly, O3 reduced petal area by 19.8 and 25% in NFA and FU+ relative to CFA, respectively. In sensitive species O3 may affect visual attraction traits important for pollination, and spectral reflectance is proposed as a novel method for studying O3 effects on flower color.

Highlights

Tropospheric ozone (O3) is one of the most important atmospheric pollutants, owing to its wide distribution and high toxicity, and it is a short-lived greenhouse gas [1,2,3,4]
Plants in charcoalfiltered air (CFA) were the least exposed to ozone, showing a filtration efficiency of 47.5% compared to the ambient O3 levels recorded in chamber-less plots (AMB) (Table 1A)
AMB and non-filtered air (NFA) open-top chambers (OTCs) exhibited comparable O3 exposures, with 2.9% lower O3 concentration in NFA compared with AMB; non-filtered air supplemented with 40 nL L−1 of O3 (FU+) plants were the most exposed, with O3 concentrations 56.4% higher than those of the ambient levels and an AOT40 around 10,000 nL L−1 h higher than that of AMB and NFA

Summary

Introduction

Tropospheric ozone (O3) is one of the most important atmospheric pollutants, owing to its wide distribution and high toxicity, and it is a short-lived greenhouse gas [1,2,3,4]. The Mediterranean basin is considered a global biodiversity hotspot that is affected by O3 pollution [10,11]. O3 effects on flower number and biomass have been used to define critical levels for O3 risk assessment on semi-natural vegetation (sensu [15]) communities within the UNECE Convention on Long-Range Transboundary Air Pollution [16,17]. Ozone can decrease the number or biomass of flowers [20,21,22,23,24,25,26,27], in some species it may have the opposite effect [28,29,30]

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