Per the United States Department of Agriculture (USDA) an invasive species is defined as:
non-native (or alien) to the ecosystem under consideration
whose introduction causes or is likely to cause economic or
environmental harm or harm to human health
Corn in the Midwest, USA (often referred to as the Corn Belt) would seem to satisfy the first requirement as an invasive species as it is not native to this area. Regarding the second requirement, it could be argued that corn in the Midwest causes environmental harm because it is in place of many indigenous plants that many other animals rely on to survive. For example, habitat loss is considered a cause in the decline of the regal fritillary (Speyeria idalia) butterfly.
A Google search brought me to this Q&A site where many argued that corn is not an invasive species because it cannot survive or spread by itself without human intervention. I tend to agree with this logic but it does not seem to be within the scope of the USDA definition.
Should corn be considered an invasive species in the Midwest?