Corn rootworm
Controlling the spread of a pest
The corn rootworm is an insect that grows on maize roots and plants.
Damage is caused mainly by older larvae that attack the brace root of the plants. These attacks result in nutritional deficiency, which weakens the plants and causes them tolean. This insect is regulated at the EU level (Directive 2000/29/EC), and is subject to mandatory control.
The corn rootworm is an insect native to Central America. During the years 1955-1970, this beetle gradually invaded North America, where it has become the main threat to maize, causing damage estimated at nearly a billion dollars a year.
Situation in France and control strategy
Detected for the first time in Europe in 1992, near the Belgrade airport, the corn rootworm then spread throughout much of Central and Southeastern Europe. Several secondary outbreaks were then detected in geographical regions non-contiguous with the initial outbreak.
Faced with the progression of this pest in Europe, in 1999 France launched an annual monitoring network that first enabled its detection in the Ile-de-France region in 2002. Since that time, this network has grown and is deployed each year in maize crops close to the insect’s entry points, especially airports and motorways.
In France, the current management policy for the corn rootworm contributes to the greater goal of reducing dependence on pesticides, by using plant protection products only when necessary (as part of the EcoPhyto Plan). Thus, control of the corn rootworm is based on a twofold approach combining crop rotation and localised insecticide treatments applied in-furrow (1/20th of the surface area of the plot); treatment of the aerial parts are reserved for situations of extremely heavy infestation.
Depending on the infestation level, the control strategy may have different objectives: eradication efforts in less infested areas and containment in more affected areas. Ultimately, the aim is to radically slow the expansion of the insect and ensure sustainable control.
The role of the Agency
ANSES, via its Plant Health Laboratory, takes part in multiple activities for the control of this pest. In 2002, it successfully confirmed the presence of the insect on French soil. It contributes significantly to the monitoring of trapping networks, and verifying the identification of new captures in affected areas. It developed the official recognition method for this insect and has produced a number of Opinions on methods for controlling it. Lastly, it is working on use of the corn rootworm as a model for studies in the methodology for plant health risk analysis.