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Aphids: Their biology, natural enemies and control
BOOK REVIEWS
405
APHIDS
Aphids: Their Biology, Natural Enemies and Control A.K. Minks and P. Harrewijn (Editors). World Crop Pests, Vol. 2C, W. Helle (Editor-in-chief), Elsevier Science Publishers, Amsterdam, The Netherlands, 1989, xvi + 312 pp., hardcover, price US$144.75, Dfl.275.00, ISBN: 0-444-42799-6. This third and final volume on aphids, in the World Crop Pests series, maintains the high standard set in the previous two volumes. It is compiled in a similar way, each section being a review of the topic by one or more appropriate authorities. In all, there are nineteen contributors. As with the second volume, there are only two chapters, in this case the first relating to damage caused by aphids, and the second devoted to methods of control. Despite the economic importance of understanding and quantifying crop loss due to aphids, remarkably little research has been undertaken on the subject. This is reflected in the fact that only one quarter of this volume is devoted to aspects of damage, and sixteen pages of that to crop loss assessment. The first part of the chapter deals with plant responses to aphid feeding, dwelling particularly on aspects of gall formation, and pointing out that damage caused by aphids is seldom as severe as would be expected. This is perhaps one reason why so few examples are available in the second section on crop loss assessment: consistent high populations are needed before valid results can be obtained. The section is, nevertheless, a useful presentation of the definitions and mathematics of crop loss. It brings out, from simulation studies, the remarkable fact that the deposition of honeydew, and resultant reduction in photosynthesis, may cause more crop loss than the direct feeding of the aphids themselves. The final section of the chapter considers aphids as the major vectors of virus diseases, discussing, in turn, transmission by non-persistent, semi-persistent, persistent and propagative means. There follows an account of the epidemiology of aphid-borne viruses and methods of reducing or circumventing an attack. Some duplication occurs here with later accounts of chemical and physical control of aphids. The second chapter of the volume, or the eleventh and final chapter of the series is concerned with all aspects of control including chemical, biological, behavioural and integrated methods. After a brief description of the types of aphicide and application methods, the section on chemical control outlines procedures to reduce direct damage or the spread of virus diseases. In each case the plant families are dealt with in turn. There follows an account of insecticide resistance in aphids, its biochemical nature and resultant problems. After an interesting account of the history of biological control of aphids, the following sections are on biological control in the open field (based mainly
406
BOOKREVIEWS
on Australian experience) and biological control in glasshouses, where aphid reproductive rates are usually so high that parasitoids and predators can seldom operate satisfactorily. Only pathogens show some promise of success. Some overlap between the information in these sections and those in volume 2 on natural enemies is perhaps inevitable. The possibility of modifying aphid behaviour are then considered, including the use of yellow traps, repellent aluminium mulches, plant odours, alarm pheromones and other chemicals. Host plant resistance can also be an effective means of discouraging aphid attack, and the various plant families are considered in turn. The final section is on integrated control: basically the combination of various methods, cultural, chemical and biological, to bring about a reduction in aphid infestation. Particular attention is paid to integrated control on cereals, potatoes and field grown vegetables, culminating in the ultimate objective of integrated farming. To sum up, these three volumes form an excellent series covering all aspects of our knowledge of aphids. Although exhibiting the enormous breadth of the subject it also reveals many gaps where information is sparse and research is still needed. Throughout the volumes, reference lists are very good (though inevitably incomplete) and should prove invaluable to any worker in the aphid field. The volumes should, in fact, be on every aphidologists' shelf and, for this reason, it is to be hoped that, before too long, an edition will be produced which is more compact and at an affordable price. I.J. WYATT
Ridge Cottage Mill Lane Worthing Sussex BNI3 3DE Great Britain
C O T T O N INSECT PESTS
Cotton Insect Pests and their Management, by G.A. Matthews. Longman Group, U.K., 1989, 199 pp., £17.95, ISBN: 0-582-00561-2. The author of this text has been personally involved with the development of insect pest control in cotton in Africa and, as cotton is the crop for which pest management is most highly developed, his book is therefore attractively authoritative. It is nice to see an introductory chapter devoted to the cotton plant and its agronomy, especially since the structure and development of the crop are so closely related to aspects of pest control. The decision subsequently to present
405
APHIDS
Aphids: Their Biology, Natural Enemies and Control A.K. Minks and P. Harrewijn (Editors). World Crop Pests, Vol. 2C, W. Helle (Editor-in-chief), Elsevier Science Publishers, Amsterdam, The Netherlands, 1989, xvi + 312 pp., hardcover, price US$144.75, Dfl.275.00, ISBN: 0-444-42799-6. This third and final volume on aphids, in the World Crop Pests series, maintains the high standard set in the previous two volumes. It is compiled in a similar way, each section being a review of the topic by one or more appropriate authorities. In all, there are nineteen contributors. As with the second volume, there are only two chapters, in this case the first relating to damage caused by aphids, and the second devoted to methods of control. Despite the economic importance of understanding and quantifying crop loss due to aphids, remarkably little research has been undertaken on the subject. This is reflected in the fact that only one quarter of this volume is devoted to aspects of damage, and sixteen pages of that to crop loss assessment. The first part of the chapter deals with plant responses to aphid feeding, dwelling particularly on aspects of gall formation, and pointing out that damage caused by aphids is seldom as severe as would be expected. This is perhaps one reason why so few examples are available in the second section on crop loss assessment: consistent high populations are needed before valid results can be obtained. The section is, nevertheless, a useful presentation of the definitions and mathematics of crop loss. It brings out, from simulation studies, the remarkable fact that the deposition of honeydew, and resultant reduction in photosynthesis, may cause more crop loss than the direct feeding of the aphids themselves. The final section of the chapter considers aphids as the major vectors of virus diseases, discussing, in turn, transmission by non-persistent, semi-persistent, persistent and propagative means. There follows an account of the epidemiology of aphid-borne viruses and methods of reducing or circumventing an attack. Some duplication occurs here with later accounts of chemical and physical control of aphids. The second chapter of the volume, or the eleventh and final chapter of the series is concerned with all aspects of control including chemical, biological, behavioural and integrated methods. After a brief description of the types of aphicide and application methods, the section on chemical control outlines procedures to reduce direct damage or the spread of virus diseases. In each case the plant families are dealt with in turn. There follows an account of insecticide resistance in aphids, its biochemical nature and resultant problems. After an interesting account of the history of biological control of aphids, the following sections are on biological control in the open field (based mainly
406
BOOKREVIEWS
on Australian experience) and biological control in glasshouses, where aphid reproductive rates are usually so high that parasitoids and predators can seldom operate satisfactorily. Only pathogens show some promise of success. Some overlap between the information in these sections and those in volume 2 on natural enemies is perhaps inevitable. The possibility of modifying aphid behaviour are then considered, including the use of yellow traps, repellent aluminium mulches, plant odours, alarm pheromones and other chemicals. Host plant resistance can also be an effective means of discouraging aphid attack, and the various plant families are considered in turn. The final section is on integrated control: basically the combination of various methods, cultural, chemical and biological, to bring about a reduction in aphid infestation. Particular attention is paid to integrated control on cereals, potatoes and field grown vegetables, culminating in the ultimate objective of integrated farming. To sum up, these three volumes form an excellent series covering all aspects of our knowledge of aphids. Although exhibiting the enormous breadth of the subject it also reveals many gaps where information is sparse and research is still needed. Throughout the volumes, reference lists are very good (though inevitably incomplete) and should prove invaluable to any worker in the aphid field. The volumes should, in fact, be on every aphidologists' shelf and, for this reason, it is to be hoped that, before too long, an edition will be produced which is more compact and at an affordable price. I.J. WYATT
Ridge Cottage Mill Lane Worthing Sussex BNI3 3DE Great Britain
C O T T O N INSECT PESTS
Cotton Insect Pests and their Management, by G.A. Matthews. Longman Group, U.K., 1989, 199 pp., £17.95, ISBN: 0-582-00561-2. The author of this text has been personally involved with the development of insect pest control in cotton in Africa and, as cotton is the crop for which pest management is most highly developed, his book is therefore attractively authoritative. It is nice to see an introductory chapter devoted to the cotton plant and its agronomy, especially since the structure and development of the crop are so closely related to aspects of pest control. The decision subsequently to present