UN Division for Sustainable Development

Case Study Detail Record

Organization type:	Intergovernmental Organization

Name of Organization:	International Centre of Insect Physiology and Ecology (ICIPE)

Name of Focal Point:	Dr. B. Löhr, International Centre of Insect Physiology and Ecology (ICIPE) P.O. Box 30772-00100 Nairobi,Kenya. Email: blohr@icipe.org

Initiative Title:	Biocontrol-based IPM for the Diamondback moth (Plutella xylostella), Eastern and Southern Africa

Internet links:	http://\\faoext06\FTP_Waicent\SD\SDA\SDAR\sard\English GP\EN GP Africa\Biocontrol_diamondbackmoth_Africa.pdf International Centre of Insect Physiology and Ecology http://www.icipe.org

Scope:	Regional: - Africa

Status:	Completed

Timeframe:	Start: 2000 End: 2007

Lead Institution:	ICIPE and the National Agricultural Research & Extension System (NARES)

Stakeholders/Partners:	Donor German Federal Ministry for Economic Cooperation and Development (BMZ) NGOs: International Centre of Insect Physiology and Ecology (ICIPE)

Relevent issues:	- Enhancing agricultural productivity through adequate and sustainable inputs - Environmentally sound pest control - Strategies for effective resource management

Objectives/Challenges:

The objective of this project is to introduce biological control scheme of DBM which avoids the environmental and human health costs, as an important alternative to synthetic pesticides.
To develop and promote effective, economical and environmentally acceptable control, the ICIPE initiated a biological control programme for Eastern and Southern Africa.

Lessons Learned:

In spite of long-lasting efforts to improve DBM management through biological means, long-term studies of the impact of its parasitoids are scarce. In this project, observations on DBM and the local natural enemy population were made fifteen months prior to and three years after release. While the displacement of indigenous parasitoids was almost complete in cultivated cabbage, they persisted on wild crucifers which grow in abundance in the surroundings of cultivated fields.
Impacts on natural resource base - Actual: Most farmers in the pilot release areas and many others in other growing areas have abandoned pesticide application against DBM. Preliminary data indicate that the cost of pesticides used in cabbage production was reduced by about 60%. A large-scale study to confirm this is under way.
Even though indigenous parasitoids were displaced from cultivated crucifers after introduction of D. semiclausum, they can still be found on wild crucifers. All are believed to have alternative hosts (e.g. potato tuber moth) in addition to DBM and had just made use of a largely unexploited resource, DBM larvae, in absence of other more specialised parasitoids. The reduction of broad-spectrum pesticide use should have increased the numbers of arthropods commonly found like spiders, ground beetles and ants.
Impacts on livelihood of the practice users - Actual: There was a considerable reduction in DBM numbers at the pilot sites, starting from already three months after release. Numbers continued to decline steadily for the three after-release years. Similarly, the percentage of attacked plants declined in the three years after release, resulting in an abatement of crop losses and an increase in economic returns. This has been observed everywhere after the release of both D. semiclausum and C. plutellae. The parasitoids have reduced production costs by 10-15%, losses by 15 (rainy season) to up to 80% (dry season) and allows farmers to take advantage of higher prices during dry seasons.
Expected: An increase in market value for pesticide free cabbage and reduced health hazards of farmers and consumers related to pesticide use.
Other impacts - Actual: Improved capacity of the extension staff at NARES General success factors
• Quick and tangible benefits for farmers
• A lack of viable alternative control options
• The efficacy of the selected biocontrol agent
• The availability of human and financial resources
• An enabling policy environment (all three release countries have regulations for the implementation of biocontrol projects)
• The collaboration of a number of institutions (ICIPE, the Asian Vegetable Research and Development Centre (supply of D. semiclausum), Plant Protection Research Institute of South Africa (research on C. plutellae, supply of parasitoids), Kenya Agricultural Research Institute (participation in baseline surveys, mass production, releases and monitoring of establishment of both parasitoids in Kenya), Plant Health Services Tanzania and National Agricultural Research, Organization Uganda (baseline surveys, releases and monitoring) and the government extension services of all three countries (farmer training activities)
Technology success factors - Improved quality and nutritional value; Increase marketability
Institutional success factors - Farmer’s capacity for adoption of the technology; Institutional support and outreach; Policy environment
Problems remaining to be resolved - The technology is suitable for many more African countries and can be implemented at relatively little additional costs in case new funding can be mobilized.

Summary:

The project was based in three countries: Kenya, Tanzania and Uganda - Wundanyi Division in Coast Province and Limuru Division in Central Province (Although this project was implemented in 3 countries, sources of information were only provided for Kenya and therefore it is the only country discussed in this paper).
This area is part of a semi-arid climatic zone. They are mid-altitude and irrigated areas.
Practice category: Managing natural resources sustainably.
Practice type: Technology for improving farm productivity sustainably; Sector Disease and pest of animals and plants.
The beneficiaries of the practice are farmers, consumers and biodiversity conservation agents.
The users of the practice are farmers.
The Natural resource used or accessed is arthropod biological control agents.

Cabbage is one of the most important vegetables grown in East Africa. It provides necessary dietary vitamins and minerals in a maize-based diet and generates substantial income for the producers and other agents involved in the marketing system, thus alleviating poverty and creating employment.
However, it is increasingly more prone to serious damage by the Plutella xylostella L., diamond back moth (DBM) often causing a complete loss of the crop. DBM also reduces marketabillity by contamination of the heads with larvae or frass. Synthetic pesticides are the major control method. The use of synthetic pesticides often leads to serious environmental problems besides affecting the health of users and consumers. They also eliminate the natural enemies of DBM, creating the need for more pesticides, increasing production costs, and the development of insecticide resistance.

Observations on DBM and indigenous natural enemy population dynamics and pest damage were conducted, including taxonomic studies through molecular techniques. This evaluation, however, failed to identify a specific and effective DBM parasitoid, and a decision was made to introduce Diadegma semiclausum, a solitary internal parasitoid with a long and successful history in the control of the pest in the highlands of Asia.
Prior to the pilot release of the parasitoid, NARES extension staff were trained in data collection and the participation of farmers in release activities was ensured. The releases were conducted at two different sites in the highlands of Kenya and sampling was conducted regularly on the control fields (fifteen farmer-managed farms).
Following the pilot release and studies of the impact of D. semiclausum, large scale releases were conducted in Kenya, Uganda and Tanzania. A second biocontrol agent for hot and dry areas, Cotesia plutellae, also a solitary internal parasitoid, was studied for three years in South Africa and then introduced. This species was released in Uganda and Kenya.