Invasion of the Frankenstein bug

Western corn rootworm in its larval stage

Super bug in its adult stage

The super bug, bane of Monsanto, has invaded.  It was found and definitely identified by an Iowa State University researcher* in four corn fields in northern Iowa.    The fields were plant with Monsanto Bt corn, which was genetically modified to specifically resist any attacks from this insect's larva.  Corn rootworm is one of the most serious pests of corn.  The western corn rootworm is the species in question.

This insect has developed through high speed evolution.  Monsanto Bt corn was modified with a gene that produces a natural insecticide in the corn that kills the pests which feed on it.  Scientists discovered a bacteria that produces a crystalline protein called Cry3Bb1.  This protein kills bugs which eat it.  They were able to extract the gene which produces this protein from the bacteria and introduce into the corn plant as part of its genetic code.  Bt corn implanted with this gene eliminates the need to use insecticides on corn because the corn plant carries its own insecticide in the seed.  

Monsanto's work in genetic modification has produced many instances of how weeds and insects can quickly evolve to develop a resistance to the substances that once killed them.  

The western corn rootworm, in the findings of the Iowa State scientists, has developed that resistance to the implanted insecticide.  And so it has resumed its munching on the roots of corn plants.  Even the ones designed to kill it.  

Monsanto has also found that weeds have the ability to foil its plans to kill them with Roundup.  Roundup is the widely used herbicide that kills all the vegetation it comes into contact with, except crop plants that are specially modified to resist the deadly effects of Roundup.  Weeds, when left to their own devices, develop the same resistance that the scientists implant into the crop seeds.

So, this year more than 11 million acres are infested with Roundup-resistant weeds, according to  Penn State University weed expert David Mortensen.  Some farmers have gone back to the old agricultural practice of manually or mechanically going after the weeds that try to crowd out their crops.  


The western corn rootworm has shown a real talent for frustrating attempts to control it.  It showed this talent in developing a resistance to the very toxic insecticides once sprayed on crops to kill it.  Then agronomists warned farmers not to plant the same crops in succeeding years but to rotate them so the rootworm would not have concentrated opportunities to develop its resistance.  However, when farmers rested a field by planting another crop with it, the corn rootworms changed their breeding schedule and rested until the insecticides were applied again, when it resumed its development of resistance.  

Monsanto scientists thought they were developing reliable crops that could withstand those things that theaten, not that they were also developing Frankenstein bugs and weeds that could come back to plague them.  But that is how nature works.

Farmers were warned, also, not to plant Monsanto Bt corn in succeeding years so that pesty critters could not have so much opportunity to develop resistance to the insecticide implanted in it.  But the high demand for corn for food and fuel made the prices high and farmers disregarded the advice to space out their plantings.  The profit motive wins out and helps the bugs recreate themselves into monster insects.  

Industrial farms are getting so huge that their operators find it necessary to go for the dollars to pay off their debts, not go for the prudent cropping plans that more carefully manage the perennial battle against pests.  

As for Monsanto, its competitors are quick to offer alternative seeds and chemicals to the ones being defeated by the corn rootworm.  And the organic farmers are doubling down on their cropping methods.

Meanwhile, rootworms are nestling down for another season of tasty corn roots.  Mother Nature does take care of her own. 


*Gassmann, A. J.,  Petzold, J. L., Keweshan, R. S., and Dunbar, M. W.  2011.  Field-evolved resistance to Bt maize by western corn rootworm.