Leafhoppers as indicators for risk assessment of GM biofortified crops
Abstract: As striking advances have been made in the last years to produce a range of biofortified GM crops with an increased level of nutrients, new approaches for environmental risk assessment on non-target arthropods have to be developed. In particular we focus on a new multivitamin maize developed at our university (Naqvi et al., 2009), producing an increased level of beta carotene, ascorbate and folate. We argue that problem formulation becomes extremely complex for this GM maize both at the plant and arthropod level. First, although the functions of carotenes and other vitamins are relatively well studied in plants, little is known about how biofortified plants modulate the metabolic pathways to increase the production of these compounds and which are their associated trade-offs. Second, studies on vitamins in insect systems are scarce, especially on their movement among trophic levels.We propose Zyginidia scutellaris (Auchenorryncha: Cicadellidae) as an indicator species to assess risks of GM maize to non-target herbivores guided by the use of the best predicted power versus replication relationships from previous field trials. Additionally, we hypothesize that this species is the base to build an indicator maize trophic chain given that it is the most abundant herbivore in maize fields. To explore the suitability of leafhoppers as indicators we present a literature review on the effects of insect resistant and herbicide tolerant GM crops and non-GM varieties on different leafhopper species. Finally we suggest an ecological risk assessment as the only way to detect the potential cascading effects of multivitamin crops.