and their representation in mathematical models. The remainder of the book is divided into three sections, concerned with digestion (eight chapters), metabolism (seven chapters) and the whole animal (six chapters). There is a reasonable degree of coherence between the individual contributions and the book as a whole succeeds in making the case for a new form of quantitative approach, which can accommodate and profit from the results of detailed research on ruminant function. The contributors do not make extravagant claims for the predictive power of the models so far developed. On the contrary, they give due emphasis to the problems and shortcomings which have been encountered and which may be turned to advantage in a more systematic choice of topics for experimental research. Neither do they neglect the essential base for the simulation models in terms of mathematical and statistical procedures to establish the form of the relationships to be incorporated in them. A reassuring feature in methodological terms is the reiteration of the fundamental principle that simulation models cannot usefully be 'adjusted' to particular data sets by normal fitting procedures: such arbitrary changes can only destroy their potential for generalization. The book is well produced and laid out, with exceptionally welldesigned diagrams which really help in understanding the text. Advanced students with a reasonable grounding in physiology and biochemistry plus some simple mathematics will find the book both accessible and useful. Researchers in this and related field will profit from the lucid and well-balanced account of this new approach, hitherto scattered in the literature.
N. R. Brockington
The Pesticide Question: Environment, Economics and Ethics. Edited by D. Pimentel and H. Lehman. Chapman and Hall, New York, 1993. 441 pp. Price: US$45.00 (hardback). ISBN 0 412 03581 2. Surveys of the public have shown that pesticides are second to nuclear power as sources of environmental concern. Unlike most other forms of pollution they are poisons deliberately placed in the environment, and they are perceived to be causing problems here and now, as well as potential unknown and long-term effects in the future. They are relatively difficult to understand, unlike emissions from car exhausts. They serve the needs of some people directly, farmers and the beneficiaries of public health programmes, and others indirectly, such as consumers of food with high cosmetic standards. But, as with any tool of production or
safety in modem society, there are hidden and external costs. Commodity prices are depressed, which is good for some but not all in society, and the average consumer cannot tell what residues are in food, or what their effect will be. Given the ubiquity of pesticides in the environment, man's role in dispersing them and the controversy over their relative benefits and costs, it is very appropriate that David Pimentel and Hugh Lehman have assembled this book to examine the issues. The authors are an unusual collection of entomologists and other scientists, economists and philosophers who present a varied and truly multidisciplinary approach to the serious ethical issues that pesticides pose. All clearly feel strongly about the need to make decisions about pesticide use and its alternatives with clear objectives and a good understanding of who benefits and how, and who pays. Various chapters catalogue the effects of pesticides on everything from soil microorganisms to humans. These should be well known to scientists, but give a good technical background to the problem for social scientists. Attempts are made to quantify these effects and to put social values on them. David Pimentel has done this in many other books, aggregating impacts and multiplying by notional costs or values, and not without criticism. However, he has given the debate an economic focal point. Do pesticide poisonings of people 'cost' the USA $787 million per year? Or of bees £320 million? The reader can see how it has been calculated which gives the opportunity to come up with a better figure. In the meantime, it is clear that the costs and benefits are not shared evenly, and that there are substantial interests at stake on both sides. The pesticide question is a global one, and while much of the book concentrates on American data and concerns, there are numerous references to the rest of the world (3 million poisonings a year, though not at $1000 a day in hospital or $2 million a life). European and Canadian efforts to reduce pesticide use by the sort of round numbers much loved by politicians are discussed. One author notes sadly that most of this effort is taking place in rich, cold regions where pesticides are relatively unnecessary anyway. The move to soil-free systems in Dutch glasshouses, happening anyway, will eliminate all soil fumigants (over three quarters of pesticide use), so even without a calculator a legislator can proceed confidently. In some cases, pesticides are only incidental to the real issues, such as the 2 million suicide attempts using pesticides, mainly in developing countries. Entomologists may find, as I did, the philosophical chapters more interesting than the technical sections as they present less familiar views. Hugh Lehman gives a clear, basic understanding of value judgements and moral obligations as they apply to the use, or non-use, of pesticides.
Much of the argument about pesticides seems to centre on how well users and other people who may be affected are informed about risks. Given the difficulty of providing complex information to so many people, and indeed the problem of comprehension on the part of many, should we abandon the risky activity, or should we accept some guardians of public safety to make decisions for the rest? We may argue about the technical competence of entomologists to understand the impacts of pesticides, but we should also be arguing about how their sense of values and obligations may differ from those of the rest of society. This is a book that should be read by all involved in pest management and environmental regulation. I will certainly use it in teaching both entomology and environmental technology. While it does not answer the pesticide question, it has tremendous value in helping us to understand what the questions (a complex set of them) are to a diverse group of concerned professionals. In this field I think it is the most interesting book since John Perkins' book Insects, Experts and the Insecticide Crisis in 1982. John D. Mumford
Conservation Policies for Sustainable Hinslope Farming. Edited by Sitanala Arsyad, Istiqial Amien, Ted Sheng and William Moldenhauer. Soil and Water Conservation Society, Ankeny, IA, 1992. 364 pp. Price: $30. ISBN 0 935734 28 7.
In the pursuit of sustainable agriculture on sloping land there is a considerable interest in the successful development and implementation of conservation farming practices. Agenda 21 has given a new dimension and added momentum to the sound management and conservation of natural resources. In the present context, the focus of Chapter l0 in Agenda 21 on an integrated approach to the planning and management of land resources and the call for a strengthening of research and the development of policies on sustainable land management makes the book both a timely and potentially important one. The book is based on material presented at a workshop on 'Conservation Farming for Sustainable Hillslope Farming' held in Solo, Central Java, Indonesia, in March 1991. The workshop was organized by the Soil and Water Conservation Society of Indonesia, in cooperation with the World Association of Soil and Water Conservation. Of the 29 published papers, a good proportion are authored by internationally recognized workers in soil conservation; 13 of the papers are from Indonesia.