3. Managing pests and optimizating pesticide use

Pests and diseases represent a major constraint to agriculture. It is thus essential to develop innovative, environment-friendly and efficient methods to limit crop damage and subsequent harvest losses. Agriculture generally involves grouping of plants of the same species in a limited area, i.e. a field or plot. This concentration increases the vulnerability of plants, with propagation of a disease or a pest being promoted by such plant concentrations in a confined area because of the continuity between plants of the same species. Agricultural intensification—and consequently homogenization within fields, increased plant densities, the use of fixed varieties or even clones—has fostered the emergence of major epidemics and the rapid development of some pests.

Farmers initially responded to such pest and disease threats by conducting chemical treatments. Due to the development of chemical industries and the economic importance of large agricultural industries, ‘efficient’ molecules have been formulated and marketed for the purpose of controlling the main crop pests and diseases. These latter organisms have, however, been able to adapt to such chemical treatments, whereby the most resistant individuals survive treatments, resulting in resistance selection. New molecules have been proposed to deal with the development of resistance to certain pesticides, the use of which has in turn led to the development of new resistance, and to the proliferation of pesticides. Then began the escalation process between the ‘appearance of new resistances’, and ‘the proposal of new molecules’, sometimes accompanied by increases in pesticide dosages and concentrations. This process has resulted in the pollution of environments and consumable products, as reflected by their ever-increasing pesticide residue contents.

This situation has prompted debate on ‘integrated control’, which is basically aimed at providing a multifactor response to problems associated with pests and diseases. Hence, a combination of:

• (i) agronomic measures,
• (ii) selection of resistant, or less susceptible, plants,
• (iii) biological control using ‘beneficials’ or biological agents that are antagonistic to pathogens,
• (iv) trapping of some specific pests, and
• (v) chemical control when unavoidable, is often proposed depending on the crop species and the pests and diseases present.

Management of cropping systems and associated pests and diseases has thus become flexible and tailored to the different situations encountered. However, chemical control is still the preferred strategy for protecting many crops because it is cost-effective and easy to implement. Environmental concerns—which are very recent in most communities—have not always prompted major changes in pest control practices. The set up and expansion of organic and fair-trade markets, further promoted by consumers, has nevertheless led to the adoption of new practices when alternatives to chemical control are available. Research is involved to an increasing extent in developing alternative methods to chemical control. The analysis and management of risks associated with pests and diseases have thus become major challenges for most teams focusing research on cropping systems. Regulation of pest populations is now a key element in projects conducted by several research units on the Agropolis International campus.

Herbicide spray around an oil palm tree ©J.P. Caliman

Agronomy research expertise

• Research projects
• Research units and teams involved

Organized diversity and pest and disease dynamics

Communities of biological organisms living in cultivated terrestrial ecosystems have an impact on their productivity and sustainability, either directly, e.g. pests and diseases, or indirectly, e.g. ‘soil engineers’ or litter processors. The working hypothesis is that the reintroduction and promotion of biodiversity in relatively nondiversified agrosystems can (...)

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Effects of shade trees on pests and diseases of Arabica coffee

Arabica coffee (Coffea arabica) may be monocropped, generally in intensive cropping systems. It is often grown under shade in agroforestry systems ranging from simple associations of two woody species to complex systems resembling natural ecosystems. The susceptibility of modern cropping systems, especially to pests and diseases, has partly been attributed (...)

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Population dynamics and natural control of pests and diseases in an orchard landscape

A very high number of orchard-wide pesticide treatments are required to control pests and diseases in apple and pear orchards. In southeastern France, the codling moth (Cydia pomonella) is the main focus of these treatments. However, the biological characteristics of this pest species (dispersal capacity, high preference for pome fruit) suggest that (...)

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OMEGA 3 project–ecological mechanisms of pest and disease management optimized to sustainably improve agrosystem productivity

High specific plant diversity (DVS) is typical of natural ecosystems, which are affected to a much lesser extent by biological attacks than cultivated ecosystems. Such attacks are generally (but not always) controlled when DVS is introduced in these latter ecosystems. CIRAD, in collaboration with its partners in tropical regions, is analysing the impacts on pathogens (...)

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Contribution to cocoa mirid control in Africa

Cocoa cropping is one of the main income sources of rural families in the forest region of Cameroon. However, this crop is hampered by pests such as mirids. Sahlbergella singularis and Distantiella theobroma are the most damaging cocoa crop pests in Africa. In some countries, they are responsible for cocoa production losses of 30-40%.

Pest

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Monitoring pest insect movements to enhance sustainable agrosystem management in sub-Saharan Africa

Understanding the spatial dynamics of pests in agrosystems, which consist of a shifting patchwork of cultivated and noncultivated habitats, facilitates prediction of outbreak risks and planning of targeted control of upsurge hotspots. This knowledge also enables ex-ante development of cropping systems in which pests are effectively managed on different (...)

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DMC for agricultural management of pest and disease resistance

High nitrogen fertilization in conventional cropping systems fosters plant parasite pressure. The processes involved can be clarified by gaining insight into the mechanisms responsible for reducing plant disease resistance. This is helpful for designing and managing highly environment-friendly cropping systems conducive to ecological intensification. CIRAD, INRA (...)

This example was not published on the print file in July 2010.

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Identifying and gaining insight into farmers’ strategies and practices to assess the impacts of vine growers’ adoption of alternative types of agriculture on a catchment scale (France)

Many INRA research programmes and expert studies are underway with the aim of finding ways to sustainably and markedly reduce pesticide use and impacts in agriculture. Viticulture is not an exception since, in France, this sector consumes 20% of all pesticides applied on only 3.7% of the utilized agricultural area (UAA). In areas where vine monoculture prevails, (...)

This example was not published on the print file in July 2010.

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Use of sanitizing plants in horticultural systems in the West Indies

In West Indian island conditions, the environmental impacts of agriculture are harshly felt: high quantities of chemical herbicides are used in tree cropping systems, while pesticides are widely sprayed in vegetable crop fields. Chemical inputs lead to soil erosion, surface water pollution and imbalances in microbial populations, including communities of beneficial

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This example was not published on the print file in July 2010.

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Research units and teams involved in "Managing pests and optimizating pesticide use"

Click on the title to see the web site	Member institutes and partners	Scientists number	Director	Description
UMR INNOVATION : Innovation and Development in Agriculture and the Agri-Food Sector The processes through which agriculture adapts are founded on technical and organizational innovations, on both a collective and an individual level.	Cirad, Inra, Montpellier SupAgro	46	Christophe Soulard	See the description
UMR SYSTEM : Tropical and Mediterranean Cropping System Functioning and Management The unit generates knowledge and tools for use in assessing, steering and developing cropping systems.	Cirad, Inra, Montpellier SupAgro	16	Christian Gary	See the description
UPR HortSys : Agroecological Functioning and Performances of Horticultural Cropping Systems Inventing an ecologically intensive type of horticulture so as to feed people better: this is a wide-ranging mandate for the unit, whose main aim is to generate and capitalize on knowledge so as to assess and design sustainable horticultural cropping systems.	Cirad	28	Eric Malézieux	See the description
UPR AMRBET : Pests and Diseases: Risk Analysis and Control Formerly: Controlling Pests and Diseases in Tree Crops Research Unit” UPR Pests and diseases hamper the productivity and sustainability of most crops, and some also affect product quality.	Cirad	17	Christian Cilas	See the description
UPR SCA : Annual Cropping Systems In the light of the recent crises in terms of commodity prices, resource use and environmental management, it is now essential to find ways of producing that are not only efficient but also more ecofriendly, economical, varied and resilient, to ensure that farmers in developing countries live better in future.	Cirad	51	Florent Maraux	See the description
UPR SIA : Conservation Agriculture and Engineering Formerly: SCV Direct Seeding and Cover Crops systems	Cirad	13	Jean-Claude Legoupil	See the description
UPR SCBPA : Banana, Plantain and Pineapple Cropping Systems Although export fruit crops are a major source of jobs and currency, they are now often barely viable, in agronomic, economic or social terms. These fruit monocultures often cause pollution and impoverish the environment. The markets are increasingly competitive and consumers increasingly demanding.	Cirad	19	Jean-Michel Risède	See the description
UR PSH : Horticultural Crops and Cropping Systems (in French)	Inra Avignon	27	Michel Génard	See the description