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Pests > Pests Entities > Insects > Moths & butterflies > Spodoptera species > Fall armyworm threatens farmers’ livelihoods
February 2017. Following an article Fall armyworm ‘threatens African farmers’ livelihoods’ on BBC News (below), a member sent the following contribution. A new threat to African agri/horticulture is beginning to show its mandibles. After a number of recent ingressions of insect pests (not talking about plant diseases now…) that spread out unhalted (Bactrocera invadens, which may actually be B. orientalis, Tuta absoluta, and others) now fall army worm is one of the latest addition to the list and this is a serious one. I found Spodoptera frugiperda on groundnut in a farm in the North of Ghana two weeks ago (my tentative identification has meanwhile been confirmed by one of the world’s specialists) and the Ghana authorities (in BCC) have been notified in a personal email exchange last week.
For those of you who are accustomed to diagnostics and not have access to taxonomic literature on the genus, I can recommend that you have a look at the diagnostic protocol for selected Spodoptera species published as a standard by EPPO: European and Mediterranean Plant Protection Organization (EPPO) You can find the diagnostic protocol in the list of standards under number “PM7/124(1)”. Please note that in my opinion the origin of a specimen as an indication for its identity IS NO LONGER VALID ! Your voracious caterpillar may well be of a newly introduced species (this also applies to the distinction between S. litura and S. littoralis, which may not be completely Asian or African any more) ! For NPPO’s this may necessitate to develop capacity for diagnostics by molecular methods, if not already available ! African Union and its regional plant protection organisation IAPSC may play a role here, but it seems IAPSC’s website (http://au-iapsc.org/) is hacked and I was unable to find information on their recent activities. Maybe the regional economic organisations such as ECOWAS, SADC, EAC, etc, or NGO’s like FAO, CABI, CIRAD, etc can assist here. We have seen suggestions to import Telenomus remus, an egg parasite, for biological control, on PESTLIST. But there are more options. The pheromone of frugiperda is known and available, for monitoring of adult (male) populations, traps can be set up to give indications on when oviposition may occur. Native generalist predators can cope with young larvae. Large larvae are eaten by insectivorous birds, cattle egrets being the most obvious ones, but also drongo and others (see the video on the S. litura management in India To spray or not to spray).
I can tell you that it was great fun to work with this development activity, led at that time by Dr J. Wightman and Dr G.V Ranga Rao. Note that in the video the lifecycle of S. litura is given as 30 days, which is too short, it actually is ca. 45 days (depending on “degree-days”) for most Spodoptera spp, but there are a good number of ideas presented in the video, which is a concise reflection of ICRISAT publications on S. litura in groundnut in India, on how to cope with armyworms in general: monitor the adult population, let the first instars be managed by generalist natural enemies, allow the insectivorous birds to eat the remaining larger caterpillars (instars 4-5) and (not part of this video but personal observation from working with Spodoptera’s in South America and South and South East Asia) preserve lizards which dig up the pupae from the soil and eat them. Use irrigation when posible to prevent large caterpillars to hide in the soil during daytime and so expose them to predation by birds. A final note on S. frugiperda: it seems there is a maize and a rice strain in this species, maybe they will even be separated as being two species, research on this is ongoing. The S. frugiperda I worked with in S. America only attacked Gramineae, maize and rice, but the one that invaded Africa now and which I collected in Ghana also goes to other crops ! Please note that I am most interested in this issue and that I am willing to assist in any possible way (as far as it is not about financial support) to develop local and ecologically oriented management of this pest. I include my contact details below. I guess this is issue deserves the nomination “to be continued”. Wishing the African communities success in coping with this challenge, I remain, With kind regards, Ernst Neering
http://www.bbc.com/news/ science-environment-38859851 Image copyright CABI Image caption The armyworm burrows into cobs Scientists are calling for urgent action to halt the spread of a pest that is destroying maize crops and spreading rapidly across Africa. The fall armyworm poses a major threat to food security and agricultural trade, warns the Centre for Agriculture and Biosciences International (Cabi). It says farmers’ livelihoods are at risk as the non-native insect threatens to reach Asia and the Mediterranean. The Food and Agriculture Organization plans emergency talks on the issue. The fall armyworm, so called because it eats its way through most of the vegetation in its way as it marches through crops, is native to North and South America but was identified for the first time in Africa last year. Cabi chief scientist Dr Matthew Cock said: “This invasive species is now a serious pest spreading quickly in tropical Africa and with the potential to spread to Asia. “Urgent action will be needed to prevent devastating losses to crops and farmers’ livelihoods.” Scientists think the caterpillar or its eggs may have reached the continent through imported produce. Once established in an area, the adult moths can fly large distances and spread rapidly. Image copyright CABI Image caption The caterpillar can march like an army across the landscape Dr Jayne Crozier, of Cabi, said the fall armyworm’s presence had now been confirmed in west Africa and was thought to be present in the south and east of the continent, many parts of which rely on maize for their staple diet. “It’s possibly been there for some time and it’s causing a lot of damage now,” she told BBC News. “The recent discovery of fall armyworm in Africa will be a huge threat to food security and also to trade in the region.” The FAO is to hold an emergency meeting in Harare between 14 and 16 February to decide emergency responses to the fall armyworm threat. It says the pest has been confirmed in Zimbabwe and preliminary reports suggest it may also be present in Malawi, Mozambique, Namibia, South Africa and Zambia. An investigation by Cabi has found that the fall armyworm is established in Ghana. Experts at Cabi say it could take several years to develop effective methods to control the pest. And they say there is confusion over the identity of the fall armyworm as it is similar to other types of armyworm, which are already present in Africa. Zambia has used army planes to spray affected areas with insecticides.
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