What constitutes optical warning signals of ladybirds (Coleoptera: Coccinellidae) towards bird predators: colour, pattern or general look? MICHAELA DOLENSKÁ, OLDR ˇ ICH NEDVE ˇ D, PETR VESELÝ*, MONIKA TESAR ˇ OVÁ and ROMAN FUCHS Faculty of Science, University of South Bohemia, Branišovská 31, 370 05 C ˇ eské Bude ˇjovice, Czech Republic Received 21 February 2009; accepted for publication 23 February 2009 Most ladybirds (Coleoptera: Coccinellidae) possess chemical protection against predators and signal its presence by less or more conspicuous coloration, which can be considered as a warning. Most ladybirds possess a dotted pattern, althougn the number, shape, and size of the spots, as well as their colour, varies considerably.Almost all ladybirds have a characteristic general appearance (body shape). We considered these traits to be used in ladybird recognition by avian predators. In the present study, we compared the reactions of avian predators (Parus major) caught in the wild, to four differently coloured ladybird beetles (Coccinella septempunctata, Exochomus quadripustulatus, Subcoccinella vigintiquatuorpunctata, and Cynegetis impunctata) and two artificial modifications of C. septem- punctata; the first was deprived of their elytral spotted pattern by painting it brown, the other had their elytra removed (i.e. altering their general ladybird appearance). Ladybirds with a spotted pattern were attacked less frequently than unspotted ones. Ladybirds with removed elytra were attacked much more often than any ladybird with a preserved general appearance. The results obtained in the present study suggest the high importance of the spotted pattern as well as general appearance in the ladybird recognition process. Additional experiments with naïve birds (hand-reared P. major) demonstrated the innateness of the aversion to two differently spotted ladybird species (C. septempunctata and Scymnus frontalis). © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 234–242. ADDITIONAL KEYWORDS: body shape – chemical signal – prey recognition – warning coloration. INTRODUCTION Warning coloration has been considered as a very important antipredatory signal subsequent to early studies dealing with aposematic animals (Komárek, 2003). This signal is addressed to optically orienting predators (Edmunds, 1974). In the case of terrestrial invertebrate prey, birds are the most common visual predators (Smith, 1980; Evans & Schmidt, 1990; Schuler & Roper, 1992; Roper & Marples, 1997; Exnerová et al., 2006). The most common colours used by insects to discourage predators from attacking them are bright red, orange, and yellow (Cott, 1940). These colours are distinctive so that predators quickly determine the connection between coloration and the toxicity of the prey (Coppinger, 1969; Gittleman, Harvey & Greenwood, 1980; Harvey & Paxton, 1981; Guilford, 1986). Nonetheless, other colours, such as white, may be utilized as antipredatory signals (Lyyt- inen et al., 1999). The importance of colour per se has been demonstrated several times using optically ori- enting predators (Sillén-Tullberg, 1985; Marples, van Veelen & Brakefield, 1994; Ham et al., 2006). Colour is not the only aspect of optical warning signals. Bright colours usually form contrasting pat- terns (often in combination with black or white), which should enhance the warning signal (Endler, 1978). The importance of patterns has been experi- mentally demonstrated using avian predators (Schuler & Hesse, 1985; Osorio, Miklosi & Gonda, 1999; Endler & Mielke, 2005). Particular parameters of colour pattern, such as symmetry and size, have *Corresponding author. E-mail: petr-vesely@seznam.cz Biological Journal of the Linnean Society, 2009, 98, 234–242. With 4 figures © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 234–242 234 Downloaded from https://academic.oup.com/biolinnean/article/98/1/234/2235995 by guest on 27 August 2022