P1: FMF October 23, 2000 11:27 Annual Reviews AR119-22 Annu. Rev. Entomol. 2001. 46:667–702 Copyright c 2001 by Annual Reviews. All rights reserved BIOLOGICAL CONTROL OF LOCUSTS AND GRASSHOPPERS C. J. Lomer,1 R. P. Bateman,2 D. L. Johnson,3 J. Langewald,1 and M. Thomas4 1International Institute of Tropical Agriculture, Plant Health Management Division, 08 BP 0932, Cotonou, Benin; e-mail: [email protected], [email protected] 2CABI Biosciences, Silwood Park, Ascot, Berks. SL5 7TA, UK; e-mail: [email protected] 3Agriculture and Agri-Food Canada, Lethbridge Research Centre, PO Box 3000 Main, Lethbridge, Alberta T1J 4BI, Canada; e-mail: [email protected] 4Leverhulme Unit for Population Biology and Biological Control, Natural Environment Research Council Centre for Population Biology and CABI Biosciences, Silwood Park, Ascot, Berks. SL5 7TA, UK; e-mail: [email protected] Key Words biopesticide, microbial control, pathogen, fungi, Metarhizium ■ Abstract Control of grasshoppers and locusts has traditionally relied on synthetic insecticides, and for emergency situations this is unlikely to change. However, a grow- ing awareness of the environmental issues associated with acridid control as well as the high costs of emergency control are expanding the demand for biological control. In particular, preventive, integrated control strategies with early interventions will reduce the financial and environmental costs associated with large-scale plague treatments. The recent development of effective oil formulations of Metarhizium anisopliae spores in Africa, Australia, and Brazil opens new possibilities for environmentally safe con- trol operations. Metarhizium biopesticide kills 70%–90% of treated locusts within 14–20 days, with no measurable impact on nontarget organisms. An integrated pest management strategy, with an emphasis on the use of Metarhizium, that incorporates Access provided by University of Lethbridge on 08/22/16. For personal use only. rational use of chemical pesticides with biological options such as the microsporid- Annu. Rev. Entomol. 2001.46:667-702. Downloaded from www.annualreviews.org ian Nosema locustae and the hymenopteran egg parasitoids Scelio spp., has become a realistic option. CONTENTS INTRODUCTION ................................................ 668 CURRENT SITUATION: Chemical Control ............................. 669 POLITICAL AND ECONOMIC ISSUES ............................... 670 ENVIRONMENTAL ISSUES ........................................ 671 MOVE TOWARDS INTEGRATED PEST MANAGEMENT .................672 ACRIDID POPULATION DYNAMICS ................................ 673 BIOLOGICAL CONTROL.......................................... 674 0066-4170/01/0101-0667$14.00 667 P1: FMF October 23, 2000 11:27 Annual Reviews AR119-22 668 LOMER ET AL DEVELOPMENT OF FUNGAL SPORE FORMULATIONS AS MYCOPESTICIDES ............................................. 675 Selection of Pathogen ............................................ 676 Natural Prevalence of Metarhizium .................................. 676 Bioassays .................................................... 677 Characterization ................................................ 678 Features of the Biology of Metarhizium: Spore Quality, Storage .............679 Mass Production ............................................... 680 Formulation and Application ....................................... 681 Metarhizium IMI 330189 Field Trials in Africa ..........................682 Field Trials with Other Metarhizium Strains Outside the African Mainland ......683 Beauveria bassiana ............................................. 684 Ecological Studies .............................................. 684 Environmental Impact and Registration ............................... 685 Operating Characteristics of Metarhizium Biopesticides ...................687 Technology Transfer and Implementation .............................. 687 OTHER MICROBIAL CONTROL AGENTS ............................. 688 Microsporidia ................................................. 688 Entomophthoralean Fungi ......................................... 689 ARTHROPOD AND VERTEBRATE NATURAL ENEMIES .................689 Egg Parasitoids ................................................ 690 CONCLUSIONS AND PERSPECTIVES ............................... 690 INTRODUCTION Locusts and grasshoppers (Orthoptera: Acrididae) represent perhaps the most con- spicuous of all insect pests and are abundant insects of dry grassland and desert. When populations of these insects build up, certain species exhibit gregarious and migratory behavior, leading to the formation of spectacular swarms. From their mention in the Bible to current media reports, these locust plagues attract public attention in a way that no other insects do; the image of a flying swarm of locusts from the desert descending onto crops never fails to stir the human conscience. Access provided by University of Lethbridge on 08/22/16. For personal use only. Annu. Rev. Entomol. 2001.46:667-702. Downloaded from www.annualreviews.org In the majority of cases, national authorities have adequate capacity to conduct preventive control measures, controlling outbreaks at an early stage through the use of chemical pesticides. In countries such as Argentina, Australia, China, Niger, and South Africa, populations of locusts and grasshoppers are monitored and treated as soon as outbreaks threaten. When pests cross national borders, internationally coordinated operations are necessary; we discuss this more complex situation in relation to the desert locust (Schistocerca gregaria Forsk˚al) below. Plagues develop only when control efforts break down, or political or natural disasters prevent access to breeding areas, and interventions do not start early enough. Control failures and plague development have occurred with the desert locust in the Red Sea basin in 1986 and 1992 (162, 163), with the migratory locust Locusta migratoria capito (Sauss) in Madagascar in 1995 (189), and with the P1: FMF October 23, 2000 11:27 Annual Reviews AR119-22 LOCUST AND GRASSHOPPER BIOCONTROL 669 Italian locust Calliptamus italicus L. in Kazakhstan in 1997 (189). Once plagues develop, curative insecticide applications become necessary over wide areas, with associated financial and environmental costs that are far in excess of the cost of preventive control. In this review we give an overview of the current status of control options against locusts and grasshoppers and the increase in environmental awareness and political issues associated with locust control. We examine developments in biological control over the last decade, with a particular focus on the development of biological pesticides based on oil formulations of fungal spores. Finally, we discuss how biological control options could be incorporated into integrated pest management (IPM) strategies, and what further research and development work is necessary to implement such IPM strategies. CURRENT SITUATION: Chemical Control Locusts were first recognized as a serious agricultural problem by British author- ities in Iraq in the 1920s (152, as cited in 186a). A series of international locust conferences took place during the 1930s, from which arose the Anti-Locust Re- search Centre , subsequently renamed the Centre for Overseas Pest Research. The Centre for Overseas Pest Research handed over responsibility for desert locust control coordination to the Food and Agriculture Organization (FAO) of the United Nations in 1953 (186). The Anti-Locust Research Centre, established in 1945, de- veloped the use of chemical pesticides against locusts, selecting dieldrin as the most effective and economical control agent because of its long persistence (13). Use of dieldrin allowed the treatment of barrier strips; migrating hopper bands would cross these strips and accumulate a lethal dose. The Anti-Locust Research Center also pioneered the aerial application of low doses of dieldrin as a fine droplet cloud to control desert locust swarms (154), one of the most efficient applications of chemical pesticides known (124). An increasing awareness of the negative environmental impact of organochlo- rine pesticides has led to restriction of their use to certain limited public health Access provided by University of Lethbridge on 08/22/16. For personal use only. Annu. Rev. Entomol. 2001.46:667-702. Downloaded from www.annualreviews.org applications. Organophosphate, carbamate, and pyrethroid pesticides replaced dieldrin for locust and grasshopper control, but these could not be tested against African locusts because populations of those insects were in recession. The up- surge in the populations of desert, migratory, and red (Nomadacris septemfasciata Serville) locusts in the early 1980s, after more than 30 years of recession, found the authorities unprepared (162, 138). Not only had trained teams dispersed, but the most effective pesticide, dieldrin, was no longer available for use. The substitute organophosphate pesticides, such as fenitrothion and malathion, had shorter en- vironmental persistence and were often repeatedly applied as blanket treatments over large areas. Ironically, such treatments may have caused greater environ- mental damage than the organochlorine treatments they were designed to replace (153). P1: FMF October 23, 2000 11:27 Annual Reviews AR119-22 670 LOMER ET AL Most modern control operations rely on safer organophosphates such as fen- itrothion, carbamates such as bendiocarb, pyrethroids such as deltamethrin and lambda-cyhalothrin, fipronil,