REVIEW Eur. J. Entomol. 99: 1-4, 2002 ISSN 1210-5759 Ultraviolet vision in European owlflies (Neuroptera: Ascalaphidae): a critical review Ka r l KRAL Institut fur Zoologie, Karl-Franzens-Universitat Graz, A-8010 Graz, Austria; e-mail:
[email protected] Key words.Owlfly, Ascalaphus, Neuroptera, insect vision, ultraviolet sensitivity, visual acuity, visual behaviour, visual pigment Abstract. This review critically examines the ecological costs and benefits of ultraviolet vision in European owlflies. On the one hand it permits the accurate pursuit of flying prey, but on the other, it limits hunting to sunny periods. First the physics of detecting short wave radiation are presented. Then the advantages and disadvantages of the optical specializations necessary for UV vision are discussed. Finally the question of why several visual pigments are involved in UV vision is addressed. UV vision in predatory European owlflies of R7 means that the former receives only the longer The European owlflies, like Ascalaphus macaronius, wavelengths, since the short wavelengths are absorbed by A. libelluloides, A. longicornis and Libelloides coccajus the latter. However, intracellular electrophysiological are rapidly-flying neuropteran insects, which hunt in open recordings or microspectrophotometry on these tiny pho country for flying insects. These owlflies are only adapted toreceptors have not been done so their spectral sensi for daytime activity. They have large double eyes, which tivity is unknown (P. Stušek, personal communication). structurally correspond to optical refracting superposition Advantages of UV vision eyes (Ast, 1920; Gogala & Michieli, 1965; Schneider et What are the advantages of using UV light for locating al., 1978; forreview, seeNilsson, 1989).