Feeding Behaviour on Host Plants May Influence Potential Exposure to Bt Maize Pollen of Aglais Urticae Larvae (Lepidoptera, Nymphalidae).

Andreas Lang,Mathias Otto

doi:10.3390/insects6030760

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. The feeding behavior of the larvae may increase possible exposure to Bt maize pollen because pollen densities are expected to be higher on the top parts and along leaf veins of nettles.

Highlights

In the European Union, genetically modified (GM) crops are regulated [1]
The larvae of the Small Tortoiseshell started to segregate during the third instar, which is in contrast to other reports that A. urticae larvae do not separate before the fourth or fifth instar [34,41]
Our results clearly show that feeding on leaf veins and midribs has to be taken into account in an exposure assessment for lepidopteran larvae

Summary

Introduction

In the European Union, genetically modified (GM) crops are regulated [1]. the release of GM crops in the environment can only be warranted after an environmental risk assessment. Insect resistance is one of the most frequent traits in transgenic crops [2]. Insect resistance is mainly conferred by the insertion of genes from the soil bacterium Bacillus thuringiensis (Bt). Such Bt plants express insecticidal Cry proteins which, in a number of cases, are directed against pest moth species (Lepidoptera) [3]. As maize pollen is dispersed by wind, the pollen can be deposited near maize fields, on the host plants of larvae of non-target butterflies e.g., [6,7,8,9]. Non-target butterfly larvae may feed plant material dusted with Bt maize pollen, being harmed sub-lethally or lethally, e.g., [10,11,12,13]

Results

Discussion

Conclusion