The trail following behaviour of Yponomeuta cagnagellus

In this study the trail following behaviour of the caterpillar Yponomeuta cagnagellus (Hubner) (Lepidoptera, Yponomeutidae) is investigated. It is demonstrated that these caterpillars follow trails made by conspecifics. Ablation experiments show that at least part of this behaviour is directed by the tactile senses, but additional chemical cues cannot be excluded. In choice experiments using trails from different species, Y. cagnagellus strongly preferred conspecific trails over those from Malacosoma neustria, but did not prefer conspecific over other Yponomeuta trails. This lack of species-specificity within Yponomeuta is discussed and it is concluded that trail following is probably of little help in the elucidation of the evolutionary history of the genus. Resume La facon dont Ypotiomeuta cagnagellus suit les pistes Cette etude traite de la facon dont les chenilles de Y. cagnagellus Hubner (Lepido. Yponomeutidae) suivent des pistes. Elles suivent les pistes de leurs congeneres. Par ablation, on peut montrer qu'une partie au moins de ce comportement est due a des perceptions tactiles, mais que l'intervention d'informations chimiques complementaires ne peut etre exclue. En presence de choix entre traces de differentes especes, elles preferent nettement les traces des congeneres a celles de Malacosoma neustria, mais ne choisissent pas entre les differentes especes d'yponomeutes. L'absence de specificite parmi le genre Yponomeuta montre que la selection des pistes est probablement de peu d'utilite pour l'etude de l'histoire evolutive du genre.