Insects 2015, 6, 760-771; doi:10.3390/insects6030760 OPEN ACCESS insects ISSN 2075-4450 www.mdpi.com/journal/insects/ Article Feeding Behaviour on Host Plants May Influence Potential Exposure to Bt Maize Pollen of Aglais Urticae Larvae (Lepidoptera, Nymphalidae) 1,2, ,† 3,† Andreas Lang * and Mathias Otto 1 Environmental Geosciences, University of Basel, Bernoullistrasse 30, Basel CH-4056, Switzerland 2 Büro Lang, Hörnlehof, Gresgen 108, Zell im Wiesental D-79669, Germany 3 Federal Agency for Nature Conservation, Konstantinstraße 110, Bonn D-53179, Germany; E-Mail:
[email protected] † These authors contributed equally to this work. * Author to whom correspondence should be addressed; E-Mail:
[email protected]; Tel.: +41-61-267-0480; Fax: +41-61-267-0479. Academic Editor: Brian T. Forschler Received: 2 June 2015 / Accepted: 21 August 2015 / Published: 31 August 2015 Abstract: Non-target butterfly larvae may be harmed by feeding on host plants dusted with Bt maize pollen. Feeding patterns of larvae and their utilization of host plants can affect the adverse Bt impact because the maize pollen is distributed unequally on the plant. In a field study, we investigated the feeding of larvae of the Small Tortoiseshell, Aglais urticae, on nettles, Urtica dioica. Young larvae used smaller host plants than older larvae. In general, the position of the larvae was in the top part of the host plant, but older larvae showed a broader vertical distribution on the nettles. Leaf blades and leaf tips were the plant parts most often consumed. Leaf veins were consumed but midribs were fed on to a lesser extent than other plant veins, particularly by young larvae.