Book reviews (PN67)  

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Healthy crops: a revolution in pest management
This translation of a 1985 publication by the French plant pathologist Francis Chaboussou for the first time makes accessible to an English-speaking audience the full details of his groundbreaking work on the adverse effects of chemical pesticides and fertilisers on plants.
    Through both laboratory and field tests, Chaboussou’s results revealed a pest response to chemical pesticides that fundamentally challenged theories of pest management and assumptions that underlie the production of most agrochemicals. His observations addressed several phenomena: why do pests attack some plants and not others? Why do pesticides fail to control certain pests? Why, after 50 years of the use of chemical pesticides, are the incidences of pest and disease attacks responsible for the same level of crop loss? Pest resistance, or loss of natural predators to unselective agrochemicals, is assumed as the reason for these unexplained occurrences, which particularly apply in the cases of insect, mite and disease pests. But Chaboussou’s research, mainly carried out at the French research centre Institut National de la Recherche Agronomique (INRA) from 1933 to1976, shows that the relationship between plant and parasite are primarily nutritional in nature. 
    ‘The resistance of a plant to its different parasites depends on the balance between protein synthesis and protein breakdown. In other words, a predominance of protein breakdown increases the plant’s susceptibility. This happens with the use of ‘poisons’ (which is what chemical pesticides are for plants), especially in multiple applications.’ Chaboussou demonstrated that protein synthesis increases the plant’s resistance, or immunity, to attack. He showed chemical pesticides cause or aggravate poor plant health, and thus encourage the development of certain pests. In human health terms, drug-induced diseases are recognised and known as ‘iatrogenic illnesses’. 
    This concept, that explains why nutritional health of a plant, is the key to understanding certain pest attacks, is known as trophobiosis. It holds that plant susceptibility to pest or disease attack and the level of proliferation or development are directly related to the biochemical state of the plant. Pests and diseases develop only when there is a nutritional deficiency, as this leads to an inhibition of protein synthesis. The proven sequence demonstrates: a deficiency 4 inhibition of protein synthesis 4 accumulation of soluble substances 4 improved nutrition of parasites 4 rapid multiplication and virulence of bacteria and viruses or other pests. 
    The use of nitrogen fertilizers and pesticides are identified as the principal cause. Both upset the relationship between uptake of nitrogen from the soil and protein synthesis. This results in soluble organic nitrogen accumulating in plant tissues, which makes them more nutritious to pests. High levels of nitrogen fertilizer do it by overloading the system. Pesticides do it by subtle, sub-lethal effects on protein synthesis of the crop. Problems that may appear as a result of malnutrition or toxic effects often appear to stem from the effects of chemical pesticides. The book explains that this may occur through the use of herbicides as well as insecticides because of their effects on soil microorganisms. For example, a study on maize grown in fields after 2,4-D application shows an effect on the nitrogen metabolism of the plant that causes increases in aphids, corn borer and brown spot. 
    Those practising integrated pest management and organic agriculture implicitly support the theory by promoting crop management strategies that prioritise soil nutrition and growing a healthy crop. These insights into why plants are attacked by pests and diseases and how pesticides often increase the likelihood of attack by pests and diseases urgently need to be taken into mainstream strategies for crop management. This book should be read by friends of sustainable pest management strategies, and its theories and insights considered by plant science researchers and industry.
Francis Chaboussou, Healthy Crops: A new agricultural revolution, The Gaia Foundation, Order direct from Amazon.co.uk, 2004, 256pp, £9.99.

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Food wars – a global battle 
To understand the full challenge that faces those seeking sustainable development, it is essential to look at the structure of the whole food chain. The arguments for promoting safer means of managing pests and conserving biodiversity, while logical, are systematically ignored. Food Wars shows how the dominance of a relatively small number of companies – operating in a global liberalised marketplace – has led to the assertion of corporate profitability over social values. The result works to the detriment of health, the environment, long-term food sovereignty, social justice and quality of life. 
    Lang and Heasman put forward a powerful argument for public policies that prioritise health above profit. They address five elements of the food world: the relationship between diet and disease; the role of business in influencing food production; cultural dimensions that affect consumption patterns; environmental degradation arising from misuse of natural resources; regulation and implementation of food policy. A ‘health first’ approach is needed to change priorities. 
    A startling revelation in the book is the comparison of hunger and obesity. While nearly a billion people suffer from hunger, 1.7 billion are over-weight or obese. At both ends of the spectrum, poor nutrition causes diet-related illnesses. Food and drink contribute to eight of the top 10 risk factors associated with non-communicable diseases. While hunger is unacceptable in a rich world, obesity creates its own problems, and the health risks are high: diabetes, cardiovascular diseases, cancers, osteoporosis and dental disease. 
    While the section of the book addressing pesticides is relatively short, the important message is the role and context of pest management strategies in the wider context of food production and consumption, and in turn the relationship to social and economic development. The book does this admirably, and makes a powerful argument for new approaches that highlight ecological integration to produce diets that are good for social justice, the environment, biodiversity and human health. 
Tim Lang and Michael Heasman, Food Wars – The Global Battle for Mouths, Minds and Markets, Earthscan, 2004, £17.99, Order direct from Amazon.co.uk

Global growth in biocontrol products
Since the last edition in 2001, many more biological products for pest, disease and weed control have come on the market, particularly macro-organisms (beneficial insects and mites), which have increased from 53 products to 127. The manual’s name change better reflects the range of products now in use. This edition describes all 127 macro-organisms, 112 micro-organisms (mostly applied as biopesticides), 58 natural products derived from plants or micro-organisms and 56 semiochemicals (insect sex pheromones, etc). Their biological mode of action is described, origin, storage and shelf-life, application regimes, and whether their use is compatible with synthetic pesticides or other chemicals. Key scientific references are given, along with target pests and crops. While the vast majority of these products are considered non-toxic and with minimal risk to non-target organisms, each entry describes any possible impacts. The manual includes in an appendix the 20 gene modifications, acknowledging the debate over their use. The manual reflects the growing importance of organic farming and the use of biocontrol products within organic and IPM systems, with a special section on organic principles, while individual entries show which products are authorised for use under IFOAM organic standards. A directory of companies selling biocontrol agents includes 40 in developing countries.
The Manual of Biocontrol Agents, 3rd edition of the Biopesticide Manual, Ed. LG Copping, British Crop Protection Council, UK, 2004, £115.00, Order direct from Amazon.co.uk

[This article first appeared in Pesticides News No. 67, March 2005, page 23]