Abstract There is increasing interest in flies as potentially important pollinators. Flies are known to have a complex visual system, including 4 spectral classes of photoreceptors that contribute to the perception of color. Our current understanding of how color signals are perceived by flies is based on data for the blowfly Lucilia sp., which after being conditioned to rewarded monochromatic light stimuli, showed evidence of a categorical color visual system. The resulting opponent fly color space has 4 distinct categories, and has been used to interpret how some fly pollinators may perceive flower colors. However, formal proof that flower flies (Syrphidae) only use a simple, categorical color process remains outstanding. In free-flying experiments, we tested the hoverfly Eristalis tenax, a Batesian mimic of the honeybee, that receives its nutrition by visiting flowers. Using a range of broadband similar–dissimilar color stimuli previously used to test color perception in pollinating hymenopteran species, we evaluated if there are steep changes in behavioral choices with continuously increasing color differences as might be expected by categorical color processing. Our data revealed that color choices by the hoverfly are mediated by a continuous monotonic function. Thus, these flies did not use a categorical processing, but showed evidence of a color discrimination function similar to that observed in several bee species. We therefore empirically provide data for the minimum color distance that can be discriminated by hoverflies in fly color space, enabling an improved understanding of plant–pollinator interactions with a non-model insect species.

中文翻译：

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食蚜蝇的心理物理学：分类还是连续的颜色辨别？

摘要 苍蝇作为潜在的重要传粉者越来越受到关注。众所周知，苍蝇具有复杂的视觉系统，包括 4 种光谱类别的光感受器，这些光感受器有助于感知颜色。我们目前对苍蝇如何感知颜色信号的理解是基于绿蝇 Lucilia sp. 的数据，在适应奖励单色光刺激后，显示了分类彩色视觉系统的证据。由此产生的对手苍蝇颜色空间有 4 个不同的类别，并已被用来解释一些苍蝇传粉者如何感知花朵颜色。然而，花蝇（Syrphidae）仅使用简单、明确的颜色过程的正式证据仍然很突出。在自由飞行实验中，我们测试了食蚜蝇 Eristalis tenax，一种蜜蜂的贝茨模拟物，通过参观花朵来获得营养。使用一系列以前用于测试授粉膜翅目物种的颜色感知的宽带相似-不同颜色刺激，我们评估了行为选择是否有急剧变化，颜色差异是否如分类颜色处理所预期的那样不断增加。我们的数据显示，食蚜蝇的颜色选择是由连续单调函数介导的。因此，这些苍蝇没有使用分类处理，但显示出与在几种蜜蜂物种中观察到的相似的颜色辨别功能的证据。因此，我们凭经验提供了可以被苍蝇颜色空间中的食蚜蝇区分的最小颜色距离的数据，从而能够更好地了解植物 - 传粉媒介与非模式昆虫物种的相互作用。