Exploration de controverses 1

Team3: séance annexe 3

Programme de gestion intégrée des ravageurs de plantes

Séance annexe 3

Lors de cette séance, nous nous sommes intéressés principalement aux moyens alternatifs aux OGM en se préoccupant des programmes de gestion intégrée des ravageurs de plantes (IPM en anglais). Ces techniques sont préconisées par la FAO. En lisant nos commentaires, nous avons trouvé un article traitant de ce sujet. En effet, en tapant, dans Google, « IPM et Diabrotica » nous avons trouvé un article de « Biocontrol News and Information 1998 Vol. 19 No. 2 59N-68N » à l’adresse suivante :
http://www.google.fr/search?sourceid=navclient&hl=fr&ie=UTF-8&oe=UTF-8&q=ipm+diabrotica+%22natural+enemies+of+diabrotica+species%22

Nous avons pu y lire quelques méthodes utilisées la lutte biologique pour contenir naturellement D. virgifera. Ces méthodes sont l’emploi de pièges à phéromones qui attire les mâles et les femelles et surtout l’introduction des prédateurs naturelles de cette chrysomèle. En effet, puisque cet insecte est sorti de son milieu naturel aux USA pour arriver en Europe, il n’était plus contenu que par la disponibilité en nourriture, en l’occurrence le maïs. Voici plus précisément de quoi il en retourne :

“… Therefore the problem is only just beginning to manifest itself and requires timely interventions to minimize the impact of this invading pest. It is assumed that D. virgifera virgifera and maize evolved together in the tropics or subtropics of Mesoamerica (Mexico/Central America) (Branson & Krysan, 1981). Important natural enemies may occur locally in areas of maize cultivation in southeastern Europe, particularly polyphagous predators, but specialized parasitoids, predators and pathogens may be lacking, because they have been left behind in the area of origin. In the absence of specialized natural enemies, Diabrotica populations in southeastern Europe are only limited by the availability of suitable food, the influence of abiotic factors, and the application of control treatments. Classical biological control has an important application in the management of invasive alien pest species in the agricultural crop environment, and allows the safe and selective control of pest species and thereby helps to protect local biodiversity. Biological control has the potential to reduce local and regional populations of western corn rootworm through the importation of specialized natural enemies from the region of origin of the pest.
In South and North America, corn rootworms are attacked by a range of pathogens, nematodes, predators and parasitoids, some of which appear to be rather specialized natural enemies of D. virgifera virgifera and related species in the soil. Recent reviews on the management strategies of Diabrotica species deal only briefly with natural control agents (Levine & Oloumi-Sadeghi, 1991; Baca et al., 1995). This paper presents a detailed literature review on natural enemies–Diabrotica species associations in South and North America…”

“… Biological techniques are useful elements of a strategic approach to the control of the western corn rootworm in southeastern Europe, leading to an integrated pest management (IPM) strategy which is likely to incorporate the use of pest monitoring systems, the release of biological control agents, cultural techniques to enhance the conservation of natural control, crop rotations and orientation disruption of Diabrotica adults. Recently, a permanent monitoring network and a trapping for containment and control programme on D. virgifera virgifera became operational in Hungary, Croatia, Romania and Bosnia-Herzegovina (Edwards et al., 1998a). In the containment and control programme, Hungarian pheromone and MultigardTM yellow sticky traps are used to capture both males and females (males
are attracted to the pheromone, while both females and males are attracted to the MultigardTM traps). The purpose of this trapping activity is to determine the feasibility of trapping as many western corn rootworm beetles as possible (Edwards et al., 1998a). It is hoped that this trapping method will slow down or possibly stop the build-up of smaller isolated D. virgifera virgifera populations. The other major activity is the area-wide management to eliminate western corn rootworm beetle populations or greatly limit the area of infestation to a more manageable unit by using Slam ®. The product Slam ® uses the ‘attract and kill’ concept whereby cucurbitacin (from the buffalo gourd root, Cucurbita spp.) acts as a feeding attractant/arrestant and is mixed with carbaryl as a toxicant (Edwards et al., 1998a). Slam ® applied by air within the known range of the infestation and some distance beyond as a buffer is being tested in Hungary (Petro et al., 1998). There is an urgent need to
look for alternatives to chemical control of D. virgifera virgifera since the main component of Slam ® is carbaryl, a highly toxic carbamate chemical, the use of which is banned in several European countries (H. K. Berger pers. comm., 1997) where D. virgifera virgifera is expected
to become established within a few years (Baufeld & Enzian, 1997). In addition, aerial applications of this commercial bait will not be permitted in several European countries (H. K. Berger pers. comm., 1997). The need to develop an IPM strategy for western corn
rootworm in Central Europe is obvious. A variety of control techniques should be considered which maximizes the use of biological and cultural control interventions and minimizes the widespread application of toxic baits. Successful biological control results from the sup-
pression of pests to a level at which they no longer cause economic damage to a crop through an enhancement of the action of natural enemies (Greathead, 1986)…”

Cet article nous montre une alternative aux OGM qui semble beaucoup plus écologique et moins dangereuse. Ceci dit, cette méthode présente un désavantage majeur. En effet, en plus des prédateurs naturels de Diabrotica virgifera, il faut importer les prédateurs de ces prédateurs afin d’éviter que ceux-ci ne deviennent eux-même envahissants.