Colour as a backup for scent in the presence of olfactory noise: testing the efficacy backup hypothesis using bumblebees (Bombus terrestris)

The majority of floral displays simultaneously broadcast signals from multiple sensory modalities, but these multimodal displays come at both a metabolic cost and an increased conspicuousness to floral antagonists. Why then do plants invest in these costly multimodal displays? The efficacy backup hypothesis suggests that individual signal components act as a backup for others in the presence of environmental variability. Here, we test the efficacy backup hypothesis by investigating the ability of bumblebees to differentiate between sets of artificial flowers in the presence of either chemical interference or high wind speeds, both of which have the potential to impede the transmission of olfactory signals. We found that both chemical interference and high wind speeds negatively affected forager learning times, but these effects were mitigated in the presence of a visual signal component. Our results suggest that visual signals can act as a backup for olfactory signals in the presence of...多数花卉会同时通过多种感官模态传递信号，但这类多模态信号展示需付出代谢成本，同时还会提升其被花卉拮抗体发现的概率。那么植物为何要投入资源打造这类高成本的多模态信号展示呢？效能备份假说（Efficacy Backup Hypothesis）提出，当环境存在波动时，各信号组分可互为备份。本研究通过探究熊蜂在存在化学干扰或强风环境下区分多组人工花卉的能力，对该假说进行了验证——这两种环境因素均有可能阻碍嗅觉信号（olfactory signals）的传递。研究结果显示，化学干扰与强风均会延长觅食工蜂的学习时长，但当存在视觉信号组分时，上述负面影响会得到缓解。本研究结果表明，当环境存在干扰时，视觉信号可作为嗅觉信号的备份……