ARMYWEB: a web resource for African
armyworm and its biological control
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Emergency Transboundary Outbreak Pest Situation Report for African Armyworm (AAW): Latest update (May 4th 2012): Current situation: "AAW situation remained relatively calm in April and only some trap catches were reported in Mbeya in Tanzania (DLCO-EA, IRLCO-CSA, and PHS/Tanzania)". Forecast: "AAW activities will likely commence in Kenya and perhaps southern Ethiopia, but other countries will likely remain calm during the forecast period (AELGA, DLCO-EA, and IRLCO-CSA)" With thanks to
Dr Yene Belayneh at USAID. You can learn more about ETOP activities and
projects by visiting: http://www.usaid.gov/our_work/humanitarian_assistance/disaster_assistance/locust/
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photo (c) Wilfred Mushobozi
![]() photos (c) Wilfred Mushobozi
![]() photos (c) Ken Wilson The Zimbabwean (12th Jan 2011): "Armyworm destroys maize" - outbreaks reported in Bulawayo, Zimbabwe
Panapress
(10th Jan 2011): "Armyworm devastates crops in Zimbabwe" - outbreaks in
northern Zimbabwe
photo (c) Wilfred Mushobozi
IRINnews (20th Jan 2010): "Kenya: worm outbreaks threaten food security" - outbreaks in central & eastern Kenya Reuters Africa (18th Jan 2010): "Dry spell, army worms damage Malawi crops" - outbreaks in Malawi Daily Nation (10th Jan 2010): "The army worm must be stopped " - outbreaks in Ukambani, Kenya The Citizen (31st Dec 2009): "Armyworm scourge spreads to ten regions" - outbreak risk in Tanzania The Citizen (30th Dec 2009): "Red alert as armyworms invade two districts" - outbreaks in Tanzania Nature News (24th Dec 2009): "Whatever happened to ... Liberia's caterpillar plague" - click here for January 2009
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Like
the infamous desert locust, the African armyworm has such a major
impact because the adult stage (a moth) is highly migratory
and the location, timing and
magnitude of its outbreaks are difficult to predict.
During
the long dry season (c. May to September), armyworms
occur at very low densities in coastal regions, and other areas where
green vegetation is available all year round. The
first outbreaks of the season occur when moths from these low-density
populations are concentrated by the convective winds associated with
the first rainstorm of the short rains in October-December. These first
outbreaks generally occur in identified primary (10)
outbreak areas in Tanzania and Kenya. They then spread sequentially
across the continent at roughly monthly intervals over a period of 5-8
months, as successive generations of adult moths migrate on the
prevailing winds and initiate new high-density larval outbreak cycles
(Figure 1). The
most reliable predictor of the annual magnitude of armyworm outbreaks
in East Africa is the amount of early-season rainfall: |
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African
armyworms play host to a highly specific baculovirus: Spodoptera
exempta nucleopolyhedrovirus (SpexNPV).
Larvae
become infected when they ingest vegetation contaminated with virus
occlusion bodies (OBs). Although
extensive epidemics of SpexNPV often cause armyworm
populations to crash (causing up to 98% mortality; Rose et
al. 2000), these natural disease outbreaks are usually far
too late in the armyworm seasonal cycle to prevent major crop damage
(see below).
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SpexNPV-infected armyworm larvae on pasture. photo (c) Bill Page |
Summary of previous research Previous research has shown the following:
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Application of chemical pesticide against armyworms on pasture. photo (c) Ken Wilson
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Armyworm Baculovirus Project The African Armyworm Baculovirus Project is a consortial project with partners in the UK and Tanzania. The main partner organisations are Lancaster University, UK; University of Greenwich, UK; EcoAgriConsult Ltd, Tanzania; and the Tanzanian Government's Ministry of Agriculture and Food Security. The ultimate goal of the African Armyworm Baculovirus Project is to further our understanding of the natural interaction between an insect host, the African armyworm (Spodoptera exempta), and its virus (SpexNPV), with a view to determining the impact of the virus on its host’s outbreak dynamics and how this might ultimately be manipulated in a novel, Africa-wide strategic control system (Box 2). The funding for this research comes
from a range of sources including The UK's Department for International
Development (DfID), the Biotechnology and Biological
Sciences Research Council (BBSRC), the Natural Environment Research
Council (NERC) and the United States Agency for
International Development (USAID). Current research is
funded by the BBSRC-DFID's Sustainable
Agriculture Research for International Development (SARID)
programme and DFID's Research
Into Use programme.
The SARID project is examining the spatio-temporal pattern of armyworm outbreaks, as well as variation in natural levels of SpexNPV in the wild (prevalence appears to vary from zero to nearly 90%) and molecular genetic variation in the vuirus. The RIU project is funding the building of a baculovirus processing plant (see below), which will take the crude SpexNPV-infected caterpillars and turn it into a dry powder formulation with a shelf-life of years. This project is also providing farmers in areas at high risk from armyworm attack with pheromone traps to monitor local moth activity (see photo below - the pheromone trap is hanging from the tree). The trap attracts moths that have migrated into the area and warns the farmers that armyworm infestations are likely in the coming few days. With this information they have time to acquire pesticide to control the armyworm and protect their crops. This 'community-based forecasting' approach has proved to be very successful. The RIU project in Tanzania plans to extend this network of local forecasters and ultimately to provide these communities with SpexNPV so that they can control the pest with a cheap and environmentally-friendly biopesticide. |

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For
enquiries about the African
Armyworm Baculovirus Project, email Professor Ken Wilson
(ken.wilson@lancaster.ac.uk)
or one of the other project partners. Consortium
Partners
Project Researchers
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Anderson, R.M.
and R.M. May (1981) The population dynamics of microparasites and their
invertebrate hosts. Phil. Trans. Roy. Soc. Lond. B.
291: 451-524. |
Armyworm caterpillars (large late-instar larvae):
Armyworm infected with SpexNPV baculovirus:











