Do insects avoid eating GMOS?

Expert response from Elizabeth Owens

Former Regulatory Compliance Scientist, DuPont Pioneer

Monday, 14/10/2013 22:01

No. Insects do not avoid eating GMOs. Let me explain why this is so.

Plant-feeding insects locate their hosts by vision, smell and taste, using sophisticated receptors in their eyes, feet, antennae and mouthparts. Insects feeding on plants can be generalists, such as grasshoppers, which feed on many different plant species, or specific to feeding on one or only a few plant species, such as many butterflies and moths. In the case of corn or maize, the key target pest insect species for corn-expressing Bt proteins, corn borers and corn rootworm, are specific feeders that use corn predominantly as a host to complete development. In this case, the adult female insect decides on what type of plant the larvae will feed by laying her eggs on or near the plant host.

Research studies have shown that while the adult females do not discriminate between conventional and Bt corn, the larvae can show a preference, but only after initially feeding.¹  The newly hatched larvae must feed on whatever plant is available to them. If that plant happens to be Bt corn and they continue feeding, they will not survive.

There are other insects that call cornfields home besides these target pests. While, in general, continuously cropped land supports less insect diversity than occurs in natural landscapes, there is a community of generalist plant feeders, insects feeding on decaying plant material and beneficial predator and parasitoid insects, in most cornfields. Studies on this insect diversity for each of the commercial Bt corn traits have shown that this community does not vary between conventional and Bt corn. A meta-analysis of studies conducted over a decade found no significant difference in the diversity of these communities beyond the targeted insect pests and their specific parasitoids.²  That’s not surprising, because biotech trait developers must study and demonstrate that the Bt trait in a plant will not adversely affect non-target insects before it can be commercialized. So this data would demonstrate that Bt crops do what they are supposed to, which is reduce the number of target insects feeding on, and damaging, that crop.

Based on this, the answer to your question is no, insects do not avoid eating GMOs.

Thank you for your curiosity about insects. Understanding insect feeding preferences is part of my job, so I always appreciate when someone wants to talk about this topic!

¹ Razze, JM, CE Mason, TD Pizzolato.  2011.  Feeding Behavior of Neonate Ostrinia nubilalis (Lepidoptera: Crambidae) on Cry1Ab Bt Corn:  Implications for Resistance Management. J. Econ. Entomol. 104(3): 806-813.

² Wolfenbarger LL, Naranjo SE, Lundgren JG, Bitzer RJ, Watrud LS (2008) Bt Crop Effects on Functional Guilds of Non-Target Arthropods: A Meta-Analysis. PLoS ONE 3(5): e2118. doi:10.1371/journal.pone.0002118