June 15, 2000

International Centre of Insect Physiology (ICIPE) -- Press Release A simple method based on careful intercropping developed by the Nairobi-based International Centre of Insect Physiology (ICIPE) is one of three new approaches being introduced to dramatically reduce losses in maize from stemborers, termites and the parasitic weed striga without the use of chemical pesticides. Maize is the most important crop in eastern and southern Africa, but losses from stemborers run to 15-40 % in the region, and from striga (Striga hermonthica) another 10-20%. When these two pests occur together, farmers can lose their entire crop. By preventing such losses, an additional 6-8 million people in the region could be fed. A Triple Winner with 'Push-Pull'

Working in collaboration with KARI, Kenya's Ministry of Agriculture and Rothamsted Experimental Station (UK), ICIPE has developed a "habitat management" system which uses two kinds of crops that are planted together with maize: a plant that repels the borers (the push) and another that attracts (pulls) them. Called "push-pull", this habitat management system is based on the ages old African practice of mixed cropping and helps restore the balance of nature that humankind has disturbed by improper agricultural practices such as over-intensive monoculture, misuse of pesticides, and soil depletion.

The push-pull system has been tested on over 450 farms in two districts of Kenya and has now been released for uptake by the national extension systems in East Africa. Participating farmers in the breadbasket of Trans Nzoia are reporting a 15-20 percent increase in maize yield. In the semi-arid Suba District-plagued by both stemborers and striga-a substantial increase in milk yield has occurred in the last 4 years, with farmers now being able to support grade cows on the fodder produced. When farmers plant maize, napier and desmodium together, a return of US$ 2.30 for every dollar invested is made, as compared to only $1.40 obtained by planting maize as a monocrop. All of this is being accomplished right now, using the conventional hybrid seeds presently available, and without the need for expensive inputs such as synthetic pesticides and fertilizers or GM seeds. Two of the most useful trap crops that pull in the borers' natural enemies are Napier grass (Pennisetum purpureum) and Sudan grass (Sorghum vulgare sudanese), both important fodder plants; these are planted in a border around the maize. Two excellent borer-repelling crops which are planted between the rows of maize are molasses grass (Melinis minutifolia), which also repels ticks, and the leguminous silverleaf (Desmodium uncinatum). Desmodium has proved to be winner with a triple action: when intercropped with maize, it can suppress striga by a factor of 40 compared to maize monocrop; its N-fixing ability increases soil fertility; and it is an excellent forage. As an added bonus, sale of desmodium seed is proving to be a new income-generating opportunity for women in the project areas. The ICIPE project, led by Principal Scientist Dr Zeyaur Khan, has also identified over 30 wild grasses (Gramineae) that can serve as the wild hosts of stemborers, and which might also prove to be candidates for use as trap plants in the push-pull tactic. The project's results demonstrate the importance of maintaining part of the wild habitat for future ecological benefits and agricultural sustainability. They also stress the value of keeping wild germplasm free from genetic pollution, as might occur with the use of certain GM crops. The underlying mechanism and chemistry of the attractive odours given off by the trap plants is being investigated, for possible use in odour-baited traps for the borers. The work on stemborers and striga is being funded by the Gatsby Charitable Foundation, UK and the Rockefeller Foundation.

ICIPE has worked closely with Kenyan institutions throughout the project. The maize varieties used for planting were developed by and are the kind of improved hybrid seeds that ICIPE will continue to use until the Centre is convinced that Bt- engineered maize is safe and provides additional benefits. Dr Hans R. Herren, Director General of ICIPE and Dr Perry Atkinson of Texas A & M University, both winners of the prestigious World Food Prize for their contribution to world food security, share the belief that long-term food security relies, among other factors, on the health of the soil biota and maintaining the land's biodiversity. In this regard, there is growing concern about the introduction of Bt maize and other genetically modified (GM) crops without adequate information on their long-term impact, such as their effects on non-target organisms, pest resistance, and gene flow into other plants. ICIPE will be addressing some of these issues in its research agenda on the environmental impact of GM crop deployment. The need for more basic research before GM crops are deployed has been recommended in a recent report of the US National Academy of Sciences on genetically engineered food. Dr Herren was honored by being elected a Foreign Associate member of the NAS in 1999. Cotesia flavipes - An Effective Little Weapon in the Battle of the Borers The spotted stemborer (Chilo partellus) is probably the most damaging of the five stemborers that occur in Kenya. Chilo eats more than the other borers, and since its introduction into Africa in the early 20th century, is slowly displacing the native stemborers. Because it is a foreign or 'exotic' species, it has no effective natural enemies here in Africa. In 1993, ICIPE introduced a small parasitic wasp called Cotesia flavipes from the borer's native home in Asia to biologically control the pest. The wasp kills the borers by searching out the larvae deep inside the stem and laying its eggs in the pest; these then hatch out and consume the borer from within. ICIPE is working closely with national programmes, particularly KARI in Kenya and others in Uganda, Somalia, Ethiopia,Mozambique, Malawi, Zambia, Zimbabwe and Zanzibar, to release Cotesia in these countries. Dr William A. Overholt, the Programme Leader, reports that following its initial releases in three locations in Kwale and Kilifi districts, the wasp has now spread across the southern part of Kenya from the Indian Ocean to the shores of Lake Victoria. In the 4-year period after its release, the wasp density remained low, but from 1997 onwards has been noticeably reducing the stemborer populations in the coastal area and some parts of Eastern Province. The little wasp is aready cutting the borer populations by as much as half in Kwale and Kilifi districts. When used together with other stemborer control tactics in an IPM strategy, this classical biological control effort will result in increased maize yields. This is being done at no cost to the region's farmers through the assistance of ICIPE's donors: the Netherlands Government, USAID, and the Rockefeller Foundation. Termite Control in Maize

Termites are becoming a serious threat to maize in many areas of eastern and southern Africa. Growers in some areas of Uganda and at the Kenya coast report 100% losses in some fields, following the introduction of improved maize varieties that lack natural resistance. Plants are attacked at all stages, but particularly when the crop is more mature. With support from ICIPE's Core Donors (Sweden, Norway, Finland, Switzerland, and Denmark), the Centre has developed a fungal product to control termites within their mounds and in crops. Unlike the commercial chemical pesticides used to control termites, this product is harmless to humans and other animals and can be prepared locally at a fraction of the cost. Dr Nguya Maniania, the Congolese scientist working for ICIPE who isolated the Metarhizium fungal strain and developed the product, reports that preliminary trials in termite-infested fields in Uganda have shown a 70% increase in maize yields when the soil is treated with the fungus. Moreover, the effect on the termite population lasts more than one season, which makes the product more convenient and affordable to use. Private partners are being sought to fund large-scale production of the product.

Capacity Building

An important part of ICIPE's mandate is the building of the region's human and institutional capacity to carry out its own research and pest management programmes. The Centre has thus far trained over 130 African scientists at PhD level through its ARPPIS Programme in collaboration with 20 of the continent's universities. A further 6000 people have been trained through short courses, training workshops and other programmes. By working in multidisciplinary teams of scientists and in close collaboration with national partners, other international research organisations, universities and the communities themselves, ICIPE is introducing efficient and sustainable pest management tactics that are harmless to the environment and to other creatures, and are within reach of Africa's poorest farmers.

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ICIPE, Nairobi, April 2000

Klaus Ammann

Botanical Garden, University of Bern

Altenbergrain 21

CH - 3013 Bern, Switzerland

Tel. +41 31 631 49 37

Fax +41 31 631 49 93

klaus.ammann@sgi.unibe.ch

http://www.botanischergarten.ch/start.htm http://sgiserv.unibe.ch/sgi/index.html

http://www.bernetourism.ch/vvb11.htm#vvb11a http://www.plant-talk.org

http://www.usask.ca/agriculture/biosafety/agenda.html http://www.esf.org/life/lp/AIGM/AIGMa.htm http://www.cid.harvard.edu/cidbiotech/bioconfpp/home.htm

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rosset@foodfirst.org

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