Understanding innate preferences of wild bee species: responses to wavelength-dependent selective excitation of blue and green photoreceptor types

Abstract

Bees have a trichromatic vision with ultraviolet, blue, and green photoreceptors in their compound eyes. While the three photoreceptor types comprise the 'color space' at the perceptual level, preferential excitation of one or two of the photoreceptor types has been shown to play an important role in innate color preferences of bumble bees. Bees have been shown to exhibit strong attraction to fluorescence emission exclusively in the blue spectral region. It is not known if emission exclusively in the green spectral region produces similar attraction. Here, we examined responses of wild bees to traps designed to selectively stimulate either the blue or the green photoreceptor using sunlight-induced fluorescence in the 420-480 or 510-540 nm region, respectively. Additionally, we probed how subtle changes in the spectral characteristics of the traps affect the bee captures once a highly selective excitation of the blue photoreceptor is achieved. It was established that selective excitation of the green photoreceptor type was not attractive, in contrast to that of the blue photoreceptor type. However, once a highly selective excitation of the blue photoreceptor type (at ~ 400-480 nm) was achieved, the wild bees favored strong excitation at 430-480 nm over that in the 400-420 nm region.

Fluorescent Pan Traps Affect the Capture Rate of Insect Orders in Different Ways

“…Our data on insect capture rates with either fluorescent or non-fluorescent stimuli shows that the choice of respective stimuli may result in a biased distribution ( Figure 3 ) of the relative abundances of different pollinator groups [ 29 ], although true bias is difficult to assess in outdoor experiments with free-flying insects where overall densities are typically unknown. Future work should dissect how the spectral profiles of coloured pan trap stimuli ( Figure 2 B) may be perceived by different insects and how the observed preferences might influence which flower colours are pollinated [ 28 , 29 , 30 , 75 , 76 , 77 ]. Corrections could then be estimated from the relative ratio of fluorescent and non-fluorescent capture rates as those shown in Figure 3 , although preference effects may potentially vary between species within the insect orders ( Tables S1 and S2 ) and so corrections would benefit longer term through validation testing with individual species.…”

“…Corrections could then be estimated from the relative ratio of fluorescent and non-fluorescent capture rates as those shown in Figure 3 , although preference effects may potentially vary between species within the insect orders ( Tables S1 and S2 ) and so corrections would benefit longer term through validation testing with individual species. We acknowledge this is very difficult: so far, colour preference testing has been successfully performed with very few species [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 75 , 76 , 77 ].…”

“…Pan traps have been proposed as an efficient method to collect insects from within a habitat with minimum sampling biases [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Different insect species, however, may present preferences in their perception of different colours [ 25 , 26 , 27 , 28 , 29 , 30 ]. For example, bees have trichromatic colour perception with ultraviolet-, blue-, and green-sensitive photoreceptors [ 31 ].…”

Light Emission in Betalains: From Fluorescent Flowers to Biotechnological Applications

“…In general, plants take advantage of visual signals to attract animals' attention for the purpose of pollination and seed dispersal. In flowers, color represents an important characteristic known to attract pollinators [44][45][46]. The capacity of insects to detect symmetry and asymmetry, and the preferences described for special patterns [47], confer relevance to color modulation in flowers and, therefore, to the optical properties of the underlying pigments.…”

An Innate Color Preference Displayed by Xenopus Tadpoles Is Persistent and Requires the Tegmentum

“…So fundamental are color cues that many color-guided behaviors are not learned but are innate. Innate color preferences have been described in many organisms including zebrafish (Spence et al, 2008;Guggiana-Nilo and Engert, 2016;Park et al, 2016), Drosophila (Lazopulo et al, 2019), bees (Ostroverkhova et al, 2018), chickens and ducks (Hess, 1956;Kovach, 1971), hawkmoths (Kuenzinger et al, 2019), and several different species of frogs and tadpoles (Muntz, 1963;Jaeger and Hailman, 1976). Experimentally, innate color-driven behaviors have provided a convenient read-out for studying photoreceptors and the ability of an organism to differentiate between different wavelengths of light.…”