Migrant pests such as locusts and quelea birds are among the most devastating pests of agriculture and grazing lands, causing huge losses when large numbers descend and feed on farmer's crops and pasture. Other migrant pests, such as armyworm and many leafhopper and planthopper species, invade crops in much smaller numbers and only cause damage after population build-up within the fields. However, they all pose a particular control problem because of their ability to destroy or severely damage crops in one locality and then, in the same or subsequent generation(s), fly hundreds of kilometres to repeat the damage elsewhere. They are no respecters of district, county or national boundaries so their management depends on co-ordinated monitoring, forecasting and control.

 

Desert Locust Swarm in Ethiopia (A. Steedman (1996) The Locust Slide Kit. Chatham, UK: Natural Resources Institute) © University of Greenwich

Since the pioneering research on locusts initiated by Sir Boris Uvarov in the 1930s, NRI has developed and maintained an international reputation in the management of migrant pests. Much of the research on the population dynamics of migrant pests is carried out to predict the movements of populations during seasonal migrations, plagues and outbreaks. Trajectory analysis and dispersal modelling are used to examine the effects of changes in wind speed and direction on the dispersal patterns of migrant pests and to suggest what areas may be linked by migrations. This research is complemented by analyses of the sequences of cropping cycles, rainfall and vegetation status that lead to changes in the development of populations. This has involved the development and use of models and GIS-based techniques to integrate and interpret biological and environmental data from a variety of sources, including field reports and satellite derived estimates of rainfall and vegetation/crop conditions.

 

Most forecasting systems for agricultural pests are based on integrating data relating to interactions between the pest, its habitat, farming practices and the weather. For migrant pests, seasonal migration patterns and the geographical extent of the pest's invasion area are additional components that have to be fully understood in developing forecasting systems to predict when and where the pests are likely to cause damage. Research is currently being carried out at NRI to help reduce both crop losses and control costs due to migrant pest outbreaks by improving forecasting and promoting the use of efficient and safe control methods.

 

© University of Greenwich

Projects

Forecasting Outbreaks of the Brown Locust in Southern Africa
Funded by DFID (2000-2003); Project Leader Jane Rosenberg

 

Identifying causes of armyworm outbreaks as part of improved monitoring and forecasting systems in Tanzania
Funded by DFID CPP (2001); Project Leader John Holt

 

Models of quelea movements and improved control strategies in Southern Africa
Funded by DFID CPP (1996-1999); Project Leader Robert Cheke

 

Statistical analyses of locust movements and their determinants in East Africa
Funded by DFID CPP (1997-1998); Project Leader Peter Burt

 

Identification of the factors which lead to change in desert locust populations in Africa and the Middle East
Funded by DFID (1996-1999); Project Leader Jane Rosenberg

Publications

Cheke, R.A., Rosenberg, L.J. and Kieser, M.E. (eds.) (2000) Workshop on Research Priorities for Migrant Pests of Agriculture in Southern Africa, Plant Protection Research Institute, Pretoria, 24-26 March 1999. Chatham, UK: Natural Resources Institute

 

Rosenberg, J. and Burt P.J.A. 1999. Windborne displacements of Desert Locusts from Africa to the Caribbean and South America. Aerobiologia 15: 167-175.

 

Rutter, J.F., Mills, A.P. and Rosenberg, L.J. 1998. Weather associated with autumn and winter migrations of rice pests and other insects in south-eastern and eastern Asia. Bulletin of Entomological Research 88: 189-197.