A compass for biological control

Abstract

Cambridge University Press, 1999. £65.00 hbk (xii + 412 pages)ISBN 0 521 57283 5Biological control of agricultural pests has a history of more than one thousand years. The method achieved recognition in 1889, when the cottony-cushion scale basin (Icerya purchasi) in California’s orange orchards was successfully controlled by an introduced predator, the Vedalia ladybeetle (Rodolia cardinalis). After the success of the Vedalia ladybeetle, numerous attempts to introduce natural enemies into new areas were carried out throughout the world. Although some of the introduction attempts resulted in spectacular success, most of them failed. Thus, biological control has not yet become a major pest-controlling method in agriculture.Traditionally, most attempts at biological control have used the introduction of natural enemies against exotic pests, but additional methods have been developed. These include periodic release of mass-produced agents (e.g. Encarsia formosa and Phyoseiulus persimilis) and augmentation of their effectiveness. Thus, biological control of greenhouse pests, such as the greenhouse whitefly (Trialeurodes vaporariorum) and the two-spotted spider mite (Tetranychys urticae), are applied in European countries; however, many greenhouse farmers in non-European countries, such as those in Japan, still rely on chemical pesticides.Many problems, such as environmental pollution, new pest resurgence and damage to human health, have arisen from the overuse of chemicals on farmland. This has led to social demands for the reduction of chemical pesticide applications in agriculture. Biological control is believed to be a potentially powerful form of pest control with few environmental disadvantages. Why, therefore, is biological control not as popular as chemical pesticides?Chemical control does not require as much information about the biology and the ecology of pests. Pest suppression is easily achieved, temporarily, by killing as many individuals of the pest population as possible. Biological control is not so simple, because it affects the interspecific relationships of organisms in the field. Processes and mechanisms of biological control are consequently complicated and its effectiveness is sensitive to environmental factors that are variable to field conditions. To increase the efficiency and the reliability of biological control, more science-based technology should be used. Intensive ecological research on the biology and ecology of both pests and natural enemies is required. But, what type of ecological research is needed?There are several good textbooks on biological control1xSee all References, 2xSee all References, 3xBiological Control. Van Driesche, R.G. and Bellows, T.S. Jr. CrossrefSee all References. DeBach’s Biological Control is the first standard textbook; Huffaker and Messenger’s Theory and Practice in Biological Control is another encyclopedic textbook; and, recently, Driesche and Bellows released their version of Biological Control, and Bellows and Fisher4xHandbook of Biological Control. Bellows, T.S. and Fisher, T.W. See all References4 released the edited Handbook of Biological Control. Although these textbooks have some chapters on the theoretical bases of biological control, they do not provide any critical appraisal of the current methods. About a decade ago, Mackauer et al.5xCritical Issues in Biological Control. Mackauer, M. See all References5 released Critical Issues in Biological Control which emphasized the importance of the scientific basis of biological control and contained numerous ideas for future research.Recently, theoretical and empirical research into biological control, which includes theoretical studies of host–parasitoid or prey–predator population dynamics, has made considerable progress (i.e. stage-structured, spatially structured, individually based and tri-trophic population models). Considerable progress has also been made in the behavioral ecology of parasitoids, such as host-feeding, host selection and sex allocation. The discovery of microorganisms that induce thelytoky (i.e. parthenogenesis in which females give rise only to female offspring; for example, uniparental reproduction of Trichogramma spp. and other parasitoids infected by Wolbachia) of parasitoids is another step forward for sex ratio modification technology in natural enemies. Application of population models to improve microbial control is also a hot field, although epidemiology itself is not new.We had been looking forward to a new critical book on biological control for the next decade. Therefore, Theoretical Approaches to Biological Control is a timely volume, which covers all the recent debates related to biological control. I am not satisfied with the present status of the scientific basis of biological control6xPerspective of practical biological control and population theories. Takagi, M. Res. Popul. Ecol. 1999; 41: 121–126CrossrefSee all References6 and hope that this new book will direct future study.