Better mate in the shade: enhancement of male mating behaviour in the cabbage butterfly, Pieris rapae crucivora, in a UV-rich environment

Abstract

SUMMARYUltraviolet (UV) vision is widespread in a variety of animals, playing important roles in behaviours such as foraging and reproduction. Despite accumulated information about UV vision and UV-dependent behaviours of animals, little is known about the effect of temporal changes and local variations in UV light on UV-dependent behaviour. Here we report the mating behaviour of male cabbage butterfly, Pieris rapae crucivora, in environments with varying content of UV light. We first confirmed that the relative UV content is higher in shaded places than in sunny places. We furthermore arranged experimental areas with varying UV contents in the field, where we compared three aspects of male mating behaviour: visual localization of females, female-searching flight and copulation success rate. In all aspects males performed more actively in UV-rich environments: males searched females for longer, approached females preferentially in the shade and copulated there more frequently. Apparently, female-searching males detect females more easily in a UV-rich environment. The present findings should be taken into consideration when UVdependent behaviours, visual mate choice in particular, are studied.

A look into the invisible: ultraviolet-B sensitivity in an insect (Caliothrips phaseoli) revealed through a behavioural action spectrum

“…In this regard, it is interesting to note that a number of studies in aquatic and terrestrial ecosystems suggest that some herbivores effectively take advantage of the host leaves to protect themselves from direct solar radiation (Wahl 2008;Ohtsuka & Osakabe 2009). In addition, UV sensitivity is known to be used by some arthropods for visual mate choice (Li et al 2008b;Obara et al 2008), with a specific UV-B response demonstrated for jumping spiders (Li et al 2008b). The relative enhancement of short-wave UV radiation in the shade may facilitate mate location within the canopy, as discussed by Obara et al (2008).…”

“…In addition, UV sensitivity is known to be used by some arthropods for visual mate choice (Li et al 2008b;Obara et al 2008), with a specific UV-B response demonstrated for jumping spiders (Li et al 2008b). The relative enhancement of short-wave UV radiation in the shade may facilitate mate location within the canopy, as discussed by Obara et al (2008).…”

Linking nutrition and sexual selection across life stages in a model butterfly system

“…A possible explanation for this result is that these low‐nitrogen diet fed males achieve high mating success by being less choosy. In P. rapae , not only females but also males exhibit mate choice (Obara, Koshitaka & Arikawa ; Obara et al . ; Tigreros unpublished).…”

Ultraviolet and yellow reflectance but not fluorescence is important for visual discrimination of conspecifics by Heliconius erato

“…While the idea that UV coloration -invisible to humans -may serve as a 'private channel' of communication has been challenged (Cronin and Bok, 2016; but see Cummings et al, 2003), there is ample evidence that UV signals are important in animal communication (Rutowski, 1977;Johnsen et al, 1998;Smith et al, 2002;Cummings et al, 2003;Robertson and Monteiro, 2005;Kemp, 2008;Obara et al, 2008;Detto and Blackwell, 2009;Painting et al, 2016). However, although many butterflies have UVvisible color patches, in the absence of behavioral evidence, it is unclear whether the UV reflectance functions as a signal or whether it is simply an epi-phenomenon of the scale structure overlaying pigment granules.…”