Chrysomèle of the roots of corn

The chrysomèle of the roots of the corn is a Insecte, about Coléoptères, ravageur of the cultures of Maïs, present in all the zone of intensive culture of corn to the the United States and the Canada, lately appeared in Europe, and located in France in 2002.

Scientific name: Diabrotica will virgifera , family of the Chrysomélidés.

Description

The adult insect measures from 5 to 6 mm length and present of the élytre S yellow sharp decorated of two longitudinal black lines. It recognizable with long the antenna S established one close to the other on the face and is folded back towards the back along the body.

Biological cycle

The cycle proceeds over one year. The females, very prolific (each female lays approximately 1000 egg S during its life) lay their eggs in the ground with the foot of the corn seedling, between August and October. The eggs resist the cold of the winter and the Larve S are born at next spring. They are inserted in the ground where, attracted towards the roots by substances emitted by those, they feed with their costs. The Nymphose intervenes at the end of one month. The first adults couple in July; the female attracts the remote male by a sexual Phéromone.

Damage

The adults can nourish themselves not only on the Maïs, but also on many other plants, of which they nourish Pollen flowers. The larvae, much more harmful, are more specialized and attack especially the root S of corn. The attacked seedlings take a form in characteristic “swan neck”.

Means of fight

  • chemical Fight: insecticidal use of S of synthesis, primarily against the larvae at the time of sowings.
  • Practical farming: the rotation of crops, corn/Soja, practiced in “Middle West” allowed initially, in the years 1980, to break the cycle of the pledged chrysomèle to corn, but since a variety of insects appeared which adapted to rotation: the females lay in soya and other cultures.
  • Use of a phéromone of synthesis: in practice, it is usable only for the detection and the monitoring of the populations. For the direct fight, it is ineffective because of considerable manpower of the populations present.

Origin and propagation

The chrysomèle of the roots of corn is originating in Central America (Panama). Its surface of extension currently recovers all the surface of corn in North America.

It appeared in Europe in 1992 close to the airport of Belgrade Serbia, where it probably landed with the American planes at the time of the war of Bosnia-Herzégovine in 1990.

On this subject, various journalists (of which those of the emission “ 90 minutes” of the television channel Canal+ ) develop a Théorie of the plot, according to which the American authorities would have voluntarily introduced and disseminated this chrysomèle, in order to support by this act of Bioterrorisme the development of the corn transgenic in Europe.

Since, the chrysomèle of corn progressed at the rate of 20 to 40 km per annum in all the directions. The Austria and the Tchéquie were reached in 2002. New hearths appeared in Italy (1998) and in Suisse (2000) close to international airports.

In France, the chrysomèle of the roots of corn was detected in August 2002 in Île-de-France, close to the airports of Roissy and Orly. In 2003, a hearth was detected in Alsace. In 2005, the situation is presented as follows:

In August 2007, the hearth close to the airport of Basle-Mulhouse (Euroairport) is again active. A chemical treatment on a close zone took place.

To try éradiquer these hearths, the French authorities conduct in September an insecticidal campaign of treatment (air spreading of Deltaméthrine) in buffer zones 20 km in diameter.

In France, the damage caused with the cultures is too weak to be perceptible, for the moment.

decree dated August 14th, 2007 http://www.admi.net/jo/20070818/AGRG0763269A.html (OJ of August 18th, 2007) fixes obligations at the contaminated zones.

External bond

  • Page on the site of the ministry for the agriculture of Ontario
  • How to contain Diabrotica? on the site Arvalis- Institute of the plant
  • Wire of agricultural information on the chrysomèle of corn on the professional site agricultural Ground-net.fr

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