Foraging Small White Butterflies, Pieris rapae, Search Flowers Using Color Vision

Kentaro Arikawa,Michiyo Kinoshita,Hisaharu Koshitaka,Yoshihiro Nakatani

doi:10.3389/fevo.2021.650069

Kentaro Arikawa, Michiyo Kinoshita + Show 2 more

Open Access

https://doi.org/10.3389/fevo.2021.650069

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Abstract

We demonstrate that the small white butterfly,Pieris rapae, uses color vision when searching flowers for foraging. We first trained newly emerged butterflies in a series of indoor behavioral experiments to take sucrose solution on paper disks, colored either blue, green, yellow, or red. After confirming that the butterflies were trained to visit a certain colored disk, we presented all disks simultaneously. The butterflies selected the disk of trained color, even among an array of disks with different shades of gray. We performed the training using monochromatic lights and measured the action spectrum of the feeding behavior to determine the targets’Pieris-subjective brightness. We used the subjective brightness information to evaluate the behavioral results and concluded thatPieris rapaebutterflies discriminate visual stimuli based on the chromatic content independent of the intensity: they have true color vision. We also found thatPierisbutterflies innately prefer blue and yellow disks, which appears to match with their flower preference in the field, at least in part.

Highlights

Color vision is the ability to discriminate visual stimuli based on the chromatic content irrespective of the brightness
For a convincing demonstration of color vision in an animal, one has to demonstrate that the animal can visually discriminate “colored” stimuli, either objects or light sources, based on their spectral contents irrespective of the intensity
The animal-subjective brightness can be obtained as the product of the physical intensity of the stimuli and the animal’s sensitivity to spectral lights

Summary

INTRODUCTION

Color vision is the ability to discriminate visual stimuli based on the chromatic content irrespective of the brightness. Flowers attract many other insects for pollination, including lepidopterans, dipterans, hemipterans, and coleopterans (Chittka and Thomson, 2001) Their visual systems are not necessarily the same as that of the honeybee. The spectral organization of the Pieris compound eye differs from that of Papilio: most notably, Pieris rapae has three classes of red receptors (Blake et al, 2019) Such a species-specific eye organization creates ecologically essential differences in the color discrimination ability. Males of the Japanese subspecies Pieris rapae crucivora search for potential mates using the wings’ UV reflection This is one of the earliest examples of how UV light affects the visual behavior of an insect (Obara and Hidaka, 1968; Obara and Majerus, 2000). We focus on this particular point and establish color vision in foraging Pieris rapae

MATERIALS AND METHODS

Experimental Setup

RESULTS

Learning Results

DISCUSSION

DATA AVAILABILITY STATEMENT