Part 1.7

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INTEGRATED POST-HARVEST MANAGEMENT OF MAIZE
IN SMALL-SCALE FARMING SYSTEMS:
THE GTZ CONTRIBUTION

O. MÜCK¹ & A. BELL²

¹	Consultant, Hamburg, Germany
2	Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH, German Technical Co-operation, Eschborn, Germany

Background

Before the arrival of the larger grain borer (LGB), Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), in Africa, traditional post-harvest management systems prevailed. They were based on tolerant varieties, preventive measures, traditional storage structures and methods and the application of traditional stored-product protectants. Major changes occurred as consequences of the "Green Revolution", social and demographic phenomena and the accidental introduction of the LGB. Earlier GTZ-assisted post-harvest interventions were geared towards technical aspects of storage including storage hygiene, rat-proofing of traditional granaries and the correct use of non-chemical and chemical stored-product protectants. GTZ was the first institution to introduce an integrated control approach against the LGB that focused on biological control with the predator Teretriosoma nigrescens Lewis (Coleoptera: Histeridae). Nevertheless, after the successful introduction and establishment of T. nigrescens in Africa the situation of the small-scale farmers continued to be difficult. Investigations showed that the problem was basically of socio-economic nature. An approach geared to "dividing the harvest" was then elaborated in order to establish a threshold limit in post-harvest operations. In a further step, a systems-oriented approach was adopted meaning that post-harvest loss prevention is nowadays considered as one element in the development of post-harvest systems. GTZ’s integrated post-harvest management services consist of toolboxes for the target groups, to support them in choosing the right solutions for their individual problems. This process is called "participatory technology development". Agenda 21 is the guiding principle for all GTZ-assisted activities including post-harvest measures, underlining that the focus of German technical co-operation has shifted from problems to people.

1.	Post-harvest loss prevention on small-scale farms in Africa before the arrival of the larger grain borer
1.1	Traditional maize post-harvest systems

Traditional maize stores like the Ebli-va in Togo and Benin or the banco silos in the Savannah zones show that efficient post-harvest management has a long tradition in Africa. African maize farmers use the following elements in traditional post-harvest management strategies:

*	the selection of varieties that are tolerant to attack by storage pests;
*	sorting and cleaning procedures;
*	storage structures that are well adapted to the local climatic conditions;
*	storage methods that reduce post-harvest losses;
*	the application of traditional stored-product protectants.

The traditional post-harvest systems have performed sufficiently well in subsistence farming. Changes in the agricultural production systems as a consequence of the "Green Revolution", however, brought new problems like the introduction of high yielding varieties that are more susceptible to the attack by stored-product insects. Comparatively recent social and demographic changes such as the trend towards urbanisation and the higher demographic growth in African countries made it necessary to raise food production. These factors led to lower tolerance levels for post-harvest losses.

1.2

The recommendations of the GTZ post-harvest project

The supra-regional GTZ post-harvest project has been working in the field of post-harvest loss prevention since the late seventies, with focus on the technical aspects of grain storage. In small-scale agriculture mainly preventive measures were promoted, based on:

^*	storage hygiene;
^*	the improvement of traditional granaries (e.g. by the installation of rodent guards);
^*	the use of non-chemical stored-product protectants (e.g. neem oil for pulses).

Since the beginning of the project, the major criteria for application strategies have been their:

^*	simplicity,
^*	local availability, and
^*	user, consumer and environmental safety.

The project also elaborated recommendations for the correct use of stored-product insecticides, the management of medium sized cereal stores at village level and loss prevention in large-scale storage installations within the framework of food security and strategic grain reserves. This work is documented in Gwinner et al. (1996) and various other publications.

2.	Biological control of the larger grain borer: The basic element of an integrated post-harvest management concept
2.1	GTZ's concept for the biological control of the larger grain borer

The magnitude of post-harvest problems in small-scale farmers' maize storage changed dramatically with the arrival of the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) in Africa around the beginning of the eighties. The history of its accidental introduction into Tanzania and Togo, its further distribution, the damages and losses due to this new pest and the first control efforts is documented in many publications (for a brief overview see Markham et al. (1994).

GTZ was the first institution to start integrated control efforts that focused from the very beginning on the development of biological methods. Microsporidia and fungi proved to be too cumbersome to develop as control agents (Henning-Helbig, 1994). The predator Teretriosoma nigrescens Lewis (Coleoptera: Histeridae), however, showed a very good potential as an antagonist (Böye, 1988). The Natural Resources Institute, Chatham, UK (NRI) and the International Institute of Tropical Agriculture (IITA) joined the biological control efforts. After the obligatory tests of the efficiency and safety, GTZ assisted the first successful release of T. nigrescens in Togo in early 1991 (Böye et al., 1994), followed by the NRI release of the predator in Kenya one year later (Hill & Nang’ayo, 1993). Monitoring showed that T. nigrescens established itself quickly and efficiently suppressed the LGB with reductions in population of 73 to 80 % after eight months of storage (Mutlu, 1994). Dry weight losses were reduced by an average of 81 % after eight months (Richter et al., 1997).

It should be mentioned that storage in traditional granaries is not the only place where T. nigrescens can act on the LGB (Markham et al., 1996). A considerable proportion of the LGB population lives in the bush on dead wood far from any maize production and storage. This population provides a permanent source of prey to T. nigrescens and it is mainly in this natural habitat where the equilibrium between the predator and the prey becomes installed and the main reduction of LGB populations takes place. This phenomenon reduces the pressure from LGB on stored maize considerably.

2.2

The problems that Teretriosoma nigrescens could not solve

The application of T. nigrescens as a biological control agent can today be considered as a full success. Nevertheless, African farmers continue to face serious post-harvest problems for the following reasons:

*	LGB is only one species out of a complex range of stored maize pests including, amongst others, Sitophilus spp.;
*	post-harvest problems are not limited to the storage period;
*	post-harvest losses are not limited to weight or quality losses but are often felt as economic losses.

In order to improve the situation, an integrated post-harvest management approach is required that includes instruments for the assessment and control of losses at the socio-economic level.

3.	Dividing the harvest: The introduction of an economic threshold in post-harvest operations
3.1	Short description of the method

The first approach to introduce economic considerations into chemical post-harvest loss prevention was the design of the concept named "dividing the harvest" (Henckes, 1994). It was inspired by the shortcomings of the first chemical control method against the LGB worked out in Tanzania by NRI. This method was based on the fact that the LGB causes considerably less damage on maize stored in grain than on maize on the cob. Its promotion was accompanied with the slogan "shell and treat" (Golob, 1988). Shelling and treating with a binary insecticide was generally recommended because the losses were considered to be so high that treatment pays off in any case.

Henckes (1994) proved, however, that during the first months of storage losses caused by the LGB and other insects are so low that the cost of treatment exceeds the value of the losses that can be prevented by applying a chemical insecticide. He developed a procedure to determine a threshold limit. The procedure requires a careful monitoring of data on crop production statistics, market prices, etc. and efficient assistance to the farmer by the agricultural extension service. As these requirements can often not be met in African countries, the concept had to be further simplified. The extension message spread today in GTZ' post harvest approach is that any maize stored on-farm for home consumption need not be treated chemically within the first three to four months after harvest (GTZ, undated a, b).

3.2

From the technical level towards a socio-economic perspective

Henckes’ concept (1994) was the starting point of a change in perspective for GTZ's post-harvest work. The socio-economic investigations by Albert (1992) in the south of Togo provided further insight in the economic importance of post-harvest maize losses and the profitability of crop protection measures. The findings of both authors and the feedback from the monitoring and evaluation of post-harvest projects encouraged GTZ to leave the well-known path of loss prevention in stored maize and to investigate complex post-harvest systems.

4.	Today's integrated approach: a toolbox for participatory extension and technology development
4.1	The background of the GTZ approach

In order to satisfy the needs of small-scale farmers, post-harvest interventions have to be directed towards:

^*	the whole range of loss factors like the LGB and other insect pests, rodents, mould, humidity, heat, etc.;
^*	all elements in the post-harvest system (harvest, drying, transportation, storage, commercialisation, processing, etc.);
^*	all levels of losses including grain losses, lost labour input, financial losses, etc.

The systems approach described in the second contribution of the authors to this workshop (Bell & Mück, 1998) covers all these factors. This new strategy makes it possible to set the priorities for an efficient post-harvest management at all levels, from the single farm up to national post-harvest policies.

The prevention of storage losses still plays an important part in post-harvest systems management. In former approaches the economic benefit of interventions was taken for granted and, therefore, the recommendations given in different countries were felt to be universally applicable under varied socio-economic conditions. Today, however, it is understood that solutions must be tailored to match the individual needs. The right recommendations have to be chosen from the tool box - the extension leaflet cited above (GTZ, undated b) is just an example.

For maize stored at farm level an integrated post-harvest management strategy may follow the pattern on the flow-chart on the following page. This pattern provides a range of options, depending on the local potential and preferences.

4.2

Participatory technology development: The farmer is the expert

Which are the most suitable loss prevention techniques to apply is a choice which, in the first place, must be made by the farmer him/herself. Assistance should be provided by agricultural extensionists who have been trained to assess the individual needs of the farmers and to design appropriate strategies. This requires a decision and testing process in the villages. The participatory technology development approach as practised by the GTZ-assisted project in Benin since 1994 (Kossou et al., 1996) is an ideal starting point for this process.

4.3

Agenda 21 as the guiding principle for the GTZ concept

German development policy and the technical co-operation by GTZ are in harmony with Agenda 21 (Mennen et al., 1997). GTZ post-harvest activities respond particularly to the following stipulations of Agenda 21 (Mück, 1997):

*	poverty alleviation,
*	food security,
*	protection of the natural resources,
*	sustainable agriculture,
*	transfer of technology, and
*	participation.

The changed priorities in GTZ's post-harvest management approach means that activities are no longer focused on technical problems like storage losses but on the people facing post-harvest problems.

Figure

Integrated Stored Maize Management
for Small-scale Farms

5.	References


Albert, H., 1992.
	Aspects économiques de la protection des stocks - l’exemple du maïs dans le sud du Togo. GTZ Eschborn, Germany.
Bell, A. & Mück, O., 1998.
	L'analyse de systèmes après-récolte: la conception de la GTZ. In this proceedings.
Böye, J., 1988.
	Autökologische Untersuchungen zum Verhalten des Großen Kornbohrers Prostephanus truncatus (Horn) (Coleoptera; Bostrichidae) in Costa Rica. Ph.D. thesis, University of Kiel, Germany.
Böye, J., Biliwa, A., Fischer, H.U., Helbig, J. & Richter, J., 1994.
	The dispersion pattern of Teretriosoma nigrescens Lewis (Col., Histeridae) after its release and monitoring of the occurrence of its host Prostephanus truncatus (Horn) (Col., Bostrichidae) in the natural environment in Togo, pp. 1098 – 1102. In Highley, E., Wright, E.J., Banks, H.J. & Champ, B.R. [eds.]: Stored-product Protection. Proceedings of the 6th International Working Conference on Stored-product Protection. Canberra, Australia. CAB, Wallingford, UK.
Golob, P., 1988.
	Chemical control of the larger grain borer, pp. 53 –69. In Schulten, G.G.M. & Toet, A.J. [eds.]: Workshop on the containment and control of the larger grain borer. Arusha, Tanzania. Report II Technical papers presented at the workshop. FAO Rome, Italy.
GTZ (a).
	Getting it right: Integrated approach for short and long-term post-harvest protection (technical leaflet). GTZ, Eschborn, Germany.
GTZ (b).
	Integrated stored product protection for farmholders. A synoptic compilation of measures to control the larger grain borer (LGB) and associated storage pests in maize and dried cassava (technical leaflet). GTZ, Eschborn, Germany.
Gwinner, J., Harnisch, R. & Mück, O., 1996.
	Manual on the prevention of post-harvest grain losses. GTZ, Eschborn, Germany.
Henckes, C., 1994.
	Dividing the harvest: an approach to integrated pest management in family stores in Africa, pp. 925 – 928. In Highley, E., Wright, E.J., Banks, H.J. & Champ, B.R. [eds.]: Stored-product Protection. Proceedings of the 6th International Working Conference on Stored-product Protection. Canberra, Australia. CAB, Wallingford, UK.
Henning-Helbig, S., 1994.
	Pathogénicité de Mattesia sp. et de Nosema sp. sur Prostephanus truncatus et la possibilité de l’utilisation de ces protozoaires dans les greniers à maïs traditionnels du Togo. GTZ, Eschborn, Germany.
Hill, M.G. & Nang’ayo, F.L.O., 1993.
	Biological control of the larger grain borer, Prostephanus truncatus, p. 44. In International Institute of Biological Control, Annual Report 1992. CAB, Wallingford, UK.
Kossou, D., Affognon, H., Zweigert, M. & Bell, A., 1996.
	Développement participatif de technologies post-récolte. Expériences du projet GTZ Lutte intégrée contre le Grand capucin du maïs et autres insectes associés dans les greniers ruraux au Bénin. Communication au Séminaire International sur Enquêtes Rapides, Enquêtes Participatives: La recherche agricole à l’épreuve des savoirs paysans. ICRA Cotonou, Benin.
Markham, R.H., Borgemeister, C. & Meikle, W.G., 1994.
	Can biological control resolve the larger grain borer crisis? pp. 1087 – 1097. In Highley, E., Wright, E.J., Banks, H.J. & Champ, B.R. [eds.]: Stored-product Protection. Proceedings of the 6th International Working Conference on Stored-product Protection. Canberra, Australia. CAB, Wallingford, UK.
Markham, R.H., Meikle, W.G., Borgemeister, C., Adda, C. & Djomanou, B., 1996.
	Progress towards integration of control strategies in West Africa, pp. 81-99. In Farrell, G., Greathead, A.H., Hill, M.G. & Kibata, G.N. [eds.]: Management of farm storage pests in East and Central Africa. Proceedings of the East and Central Africa Storage Pest Management Workshop, Naivasha, Kenya 14-19 April 1996. International Institute of Biological Control, Silwood Park, UK.
Mennen, H., Mück, O. & Posamentier, H., 1997.
	The Implementation of Agenda 21 and German Development Assistance: The Case of Plant Protection. Forum Umwelt & Entwicklung, Bonn, Germany.
Mück, O., 1997.
	Integrierter Nachernteschutz in bäuerlichen Lagersystemen Afrikas, pp. 19–21. In Forum Umwelt und Entwicklung [ed.]: Pflanzenschutz und nachhaltige Landwirtschaft. EPD Entwicklungspolitik, Materialien III/97, Frankfurt, Germany.
Mutlu, P., 1994.
	Ability of the predator Teretriosoma nigrescens Lewis (Col.: Histeridae) to control the larger grain borer (Prostephanus truncatus) (Horn) (Coleoptera: Bostrichidae) under rural storage conditions in the southern region of Togo, pp. 1116-1121. In Highley, E., Wright, E.J., Banks, H.J. & Champ, B.R. [eds.]: Stored-product Protection. Proceedings of the 6th International Working Conference on Stored-product Protection. Canberra, Australia. CAB, Wallingford, UK.
Richter, J., Biliwa, A., Helbig, J. & Henning-Helbig, S., 1997.
	Impact of Teretriosoma nigrescens Lewis (Coleoptera: Histeridae) on Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) and losses in traditional maize stores in Southern Togo. Journal of stored Product Research 33: 137-142.