Langford Ben, Ryalls James M W, Mullinger Neil J, Hayden Paul, Nemitz Eiko, Pfrang Christian, Robins Alan, Touhami Dalila, Bromfield Lisa M, Girling Robbie D
UK Centre for Ecology & Hydrology, Penicuik, Midlothian, EH26 0QB, UK.
School of Agriculture, Policy and Development, University of Reading, RG6 6EU, UK.
Environ Pollut. 2023 Nov 1;336:122336. doi: 10.1016/j.envpol.2023.122336. Epub 2023 Aug 16.
The critical ecological process of animal-mediated pollination is commonly facilitated by odour cues. These odours consist of volatile organic compounds (VOCs), often with short chemical lifetimes, which form the strong concentration gradients necessary for pollinating insects to locate a flower. Atmospheric oxidants, including ozone pollution, may react with and chemically alter these VOCs, impairing the ability of pollinators to locate a flower, and therefore the pollen and nectar on which they feed. However, there is limited mechanistic empirical evidence to explain these processes within an odour plume at temporal and spatial scales relevant to insect navigation and olfaction. We investigated the impact of ozone pollution and turbulent mixing on the fate of four model floral VOCs within odour plumes using a series of controlled experiments in a large wind tunnel. Average rates of chemical degradation of α-terpinene, β-caryophyllene and 6-methyl-5-hepten-2-one were slightly faster than predicted by literature rate constants, but mostly within uncertainty bounds. Mixing reduced reaction rates by 8-10% in the first 2 m following release. Reaction rates also varied across the plumes, being fastest at plume edges where VOCs and ozone mixed most efficiently and slowest at plume centres. Honeybees were trained to learn a four VOC blend equivalent to the plume released at the wind tunnel source. When subsequently presented with an odour blend representative of that observed 6 m from the source at the centre of the plume, 52% of honeybees recognised the odour, decreasing to 38% at 12 m. When presented with the more degraded blend from the plume edge, recognition decreased to 32% and 10% at 6 and 12 m respectively. Our findings highlight a mechanism by which anthropogenic pollutants can disrupt the VOC cues used in plant-pollinator interactions, which likely impacts on other critical odour-mediated behaviours such as mate attraction.
动物介导的授粉这一关键生态过程通常由气味线索促成。这些气味由挥发性有机化合物（VOCs）组成，其化学寿命往往较短，它们形成了传粉昆虫定位花朵所需的强浓度梯度。包括臭氧污染在内的大气氧化剂可能与这些VOCs发生反应并对其进行化学改变，从而损害传粉者定位花朵的能力，进而影响它们获取食物的花粉和花蜜。然而，在与昆虫导航和嗅觉相关的时间和空间尺度上，解释气味羽流中这些过程的机制性实证证据有限。我们在一个大型风洞中进行了一系列对照实验，研究了臭氧污染和湍流混合对气味羽流中四种典型花卉VOCs命运的影响。α-萜品烯、β-石竹烯和6-甲基-5-庚烯-2-酮的平均化学降解速率略快于文献速率常数的预测，但大多在不确定范围内。在释放后的前2米内，混合使反应速率降低了8 - 10%。反应速率在羽流中也有所不同，在羽流边缘最快，那里VOCs和臭氧混合最有效，在羽流中心最慢。蜜蜂经过训练学习一种相当于风洞源头释放的羽流的四种VOC混合物。随后，当在羽流中心距离源头6米处呈现一种代表所观察到的气味混合物时，52%的蜜蜂能识别出该气味，在12米处这一比例降至38%。当呈现来自羽流边缘降解程度更高的混合物时，在6米和12米处识别率分别降至32%和10%。我们的研究结果突出了一种机制，通过该机制人为污染物可扰乱植物 - 传粉者相互作用中使用的VOC线索，这可能会影响其他关键的气味介导行为，如配偶吸引。
