Fighting mite with mite
MetadataShow full item record
CTA. 2008. Fighting mite with mite. Rural Radio Resource Pack 08/2. Wageningen, The Netherlands: CTA.
Permanent link to this item: http://hdl.handle.net/10568/57153
Using a predatory mite to control cassava green mite
Fighting mite with mite Cue: Cassava is a vital food crop for more than 200 million people in Africa. Its starchy roots provide food security in areas of low rainfall, and its leaves are also a nutritious vegetable. But cassava crops across the continent are threatened by a tiny, but deadly enemy - the cassava green mite. This insect pest came to Africa from South America in the early 1970s, and was first detected near Kampala in Uganda. Over the next 20 years it spread across Africa?s cassava growing belt, causing huge losses in yield of up to 80 per cent in some areas. Attacking the pest by using chemical sprays is difficult, not least because the mites live on the underside of cassava leaves. But in Uganda, and other countries, cassava farmers are increasingly using a different approach to pest control, as Wambi Michael discovered when he met with Stella Adumo, Senior Technician at Uganda?s National Agricultural Research Organisation laboratories in Kawanda. Wambi began by asking Stella to describe the damage caused by the mite. IN: ?It is a very serious pest in almost ? OUT: ? and the yield improves drastically.? DUR?N: 4?44? BACK ANNOUNCEMENT: Stella Adumo, Senior Technician at the NARO laboratories in Kawanda, Uganda. The interview comes from a resource pack produced by CTA. Transcript Adumo It is a very serious pest in almost all cassava growing areas. It is a dry weather pest, and it attacks almost every variety of cassava. And it is a pest which attacks the tip of the plant. When it attacks the tip of the cassava plant it causes chlorosis of that plant, that is, the plant loses colour and becomes yellowish. In severe cases you will find that there will be drying of the leaves and defoliation. The effect of this pest goes down even to the root system. The tubers get drastically reduced, and in cases where tubers have already been manufactured, you realise even rotting of the tubers. Michael So how can the pest be identified? Adumo This pest is found under the leaves of the cassava plant, and in most cases it is at the growing shoot. When you turn the leaf upside down, you find that they are under the leaves of the cassava plant, and they are very tiny in size and greenish in colour. Michael So what biological control methods have been adopted in Uganda to control the cassava green mite? Adumo Biological control is using natural enemies to control pests and weeds, and for this case, it uses a predatory mite that is called Typhlodromalus aripo. It is a mite that feeds on the cassava green mite. It sucks out all the fluid and renders the pest dead. Michael How can the beneficial insects be identified? Adumo The beneficial insect, as I said, is also a mite, but it is a predatory mite. The pest is greenish in colour. The natural enemy is brownish in colour and slightly bigger than the pest, and a farmer can only identify it when he checks at the tip of a cassava plant. These natural enemies live at the tip of a cassava plant, and when the farmer opens the tip of a cassava plant they will be very shifty, running up and down, they are very fast, because they have a good searching ability. Michael How can farmers encourage beneficial insects to control this problem? Adumo These natural enemies have already been released in the field and they are multiplying out in the field. Now a farmer has to have proper management practices in the field in order to promote the development of this natural enemy. They should avoid unnecessary burning, because in most cases the unnecessary burning destroys the natural enemies that are already out in the field. Now if a farmer has that problem of green mite, try the next field, check the tip of the plant, check for that brown mite. If they find it there, break the tip, move to the affected area where there is a lot of pest and just place that tip on top of the affected plant. The natural enemy will automatically crawl from this tip to the plant which is affected and will work on the cassava pest which is there, and destroy it. Michael So the beneficial insect; isn?t it in any way dangerous to the environment? Adumo Uganda is not the first place where we have released this natural enemy. It has been tried in other countries, and the fact is that it does not affect any other insect, any other plant except its host, and that is the green mite. It is host specific, it cannot attack any other but it only attacks the cassava green mite. Michael So this beneficial insect, what impact has it had on the cassava production in the country? Adumo In many areas they had realised low yields of cassava. But when the natural enemy reached in some of those areas the yields of cassava were raised, and also the planting material was improved. Another thing we realised is, this insect is cost effective. When you release it in the field it multiplies on its own, so the farmer does not have the bother of again going back and releasing in the same place. So a farmer just benefits as the insect multiplies and destroys the pest. Michael So there is no cost related to spraying the cassava? Adumo There is not cost at all, because this is a natural, a living thing. When it multiplies it moves under ? remember one thing. Cassava has a very heavy canopy, so when you think about spraying it is even difficult to spray under the leaves where the insect is. Now with this natural enemy, it goes searching all over the area, under the leaves and it attacks the pest which is damaging the crop, and you find automatically that the crop improves and the yield improves drastically. End of track