NIW Insect of the day: African armyworm

Posted 27 June 2014

This Insect of the Day feature has been produced as part of Harper Adams University's National Insect Week celebrations, June 23-29.

The African armyworm by Senior Lecturer in Entomology, Dr Rob Graham.

Armyworm. The very word conjures up visions of destruction and invasion– and that is precisely the behaviour of this marauding insect pest!

The African armyworm, Spodoptera exempta, is a moth predominately found in sub-saharan Africa. It is probably the most destructive pest in eastern Africa, with outbreaks of caterpillars capable of destroying a farmer’s entire crop, feeding upon all types of staple cereal and grazing crops.

The adult moths live about 10 days and can migrate hundreds of kilometres, making it very difficult to predict the location of the next outbreak.

The female can lay about 1000 eggs in her lifetime. Eggs hatch in two to five days and six caterpillar stages are completed within two to three weeks. Caterpillars occur in two morphologically distinct forms: a 'gregarious' form, which is black, and a 'solitary' form, which is green, determined entirely by density.

UK scientists are part of an international team currently involved in combating this pest using a naturally occurring pathogen, the baculovirus SpexNPV, as a biopesticide. Ongoing research on the biology, ecology and genetics of SpexNPV is trying to assess its potential use as a microbial pesticide http://www.lancaster.ac.uk/armyworm/

This is one of the major insect pests and threats to food security in sub Saharan Africa; but it truly is a spectacular and remarkable insect with a fascinating life-history!