Pest Management in North West Africa


This webpage is designed to give a small introduction to the background of pest and their management in northern and western Africa. The most common diseases and pests are listed, however this page can be most useful as a starting point for more specific questions.
This site was created by:
Katrin Schmidt:
Evan Kane:
Wendy Owens:

Table of Contents

Staple Crops

Maize Borer

Cassava Mealy Bug

Useful publications:

Pyralidae spp.

Bean Pod-borers

Common bean pests/bean flies

Helpful links for pest/crop interactions

Helpful links for intercropping

Other useful links




Staple Crops

Between 20 - 40% of the worlds food supply is lost during production and post-production to insect pests. Maize and sorghum are important staple crops for millions of people in east and southern Africa. Food security is under considerable threat from a lot of groups of insect pests.


young women carrying maize home


sorghum just before harvest

Maize Borer

In a lot of parts in North West Africa pests attacking maize are a big problem. Especially the Maize Borer can develope big populations and destroy half of the yield in one year. Stemborers, the larval stage of certain
kinds of moth, cause losses in maize running into the millions of tonnes annually, enough to feed more than seven and a half million people
in the region for a year. Losses caused by stemborers in these two grains are typically in the neighborhood of 20–40% of the potential
yield. The pests are particularly difficult to control by conventional means because the damaging larvae are hidden away deep inside the plant
stems. Over the past 5 years,The International Centre of Insect Physiology and Ecology (ICIPE) (sometimes this link does not work) has specialized in developing methods for managing these devastating insects by avoid the use of environmentally damaging and expensive synthetic insecticides. The Plant Pathology Department of the University of Hannover, Germany worked together with this institution and had several projects in Benin, to search for biocontrols for this insect.




a picture of the maize stemborer



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Cassava Mealy Bug

Other important crops in this region are cassava and millet. The two crops are also threaten by pests.

cassave is mostly processed in the villages

here: women and younger kids help to peel the tubers for further food preparation



Cassava is an introduced crop from South America but it is now well established in Africa.


millet harvest

The most severe one is the cassava mealy bug. Its larvae feeds on all kinds of sweet potato and can destroy the total yield of one year. As for most of the insect pests, plant pathology agencies try to find a natural enemy for these pests. The International Institute of Tropical Agriculture (IITA) launched a search for the natural enemy in South America in 1980. It was found that the most successful biological agent against mealybugs is a parasitic wasp (Epidinocarsis Lopezi).

mealybugs attacking cassava leaves



the antagonist of the mealy bug :a small wasp



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Here are some useful publications:

Influence of intercropping on the abundance, distribution and parasitism of Chilo spp. (Lepidoptera: Pyralidae) eggs. Pats, P., Ekbom, B., Skovgard,H. , 1997, Bulletin of entomological research. V:87, pp. 507-513.

ABSTRACT: Two of the most common and serious pests of maize and sorghum in the coastal areas of East Africa are the pyralid species, Chilo partellus (Swinhoe) and C. orichalcociliellus (Strand). Maize monocrop (with high and low plant density) and maize/cowpea mixed intercrop field experiments were conducted in Kenya to test if intercropping decreased the number of egg batches laid, altered the distribution of the egg batches and influenced egg parasitism. There was no significant difference in the number of egg batches per plant between treatments and the egg batches were randomly distributed on
and among plants in most of the plots for all three treatments. There was a tendency for higher egg parasitism in the intercrop. The proportion of eggs parasitized was significantly correlated with total number of eggs per plot suggesting a positive density dependent response. It is concluded that intercropping does not affect C. partellus nor C. orichalcociliellus oviposition behaviour but egg parasitism is likely to be augmented.

Effects of intercropping with maize on the incidence and damage caused by pod borers of common beans, Karel, A., 1993, Environmental entomology, v.22, pp. 1076-1083.

ABSTRACTS: Effects of intercropping common bean, Phaseolus vulgaris L., with maize, Zea mays L., at four plant populations on the pod borers Maruca testulalis Geyer and Heliothis armigera Hubner
on common bean were studied. The incidence of M. testulalis and H. armigera larvae was significantly (P < 0.05) lower in intercropped and higher plant populations than in pure stands and lower plant populations of common bean; larval populations of M. testulalis increased 45-59 d after planting, followed by a decrease up to 66 d after planting. Percentages of damage to flowers and pods by larvae of the two pod borer species were significantly (P < 0.05) lower in an intercrop combination of one-third bean-two-thirds maize
(BMM) than in pure bean (BBB). Flower and pod damage decreased when plant populations increased from 66,666 to 1,333,333 plants per ha. The relationship of intercrop combinations and individual plant populations to incidence and damage by pod borer larvae was established by exponential
and power regression models. Seed yields of intercrop combinations of BBM and BMM were higher than those of the two crops when grown in monoculture at 133,333 and 266,666 plants per ha. "Relative yield total" thus indicated yield advantages of 16-29% for plant populations of 133,333 plants per ha in both BBM and BMM intercrop combinations, which was associated with lower incidence and damage by pod borer species. Intercropping beans with maize was considered useful as a cultural method for controlling pod borers on common beans and for higher seed yield of the two crops.

Mechanisms of alteration in bean rust epidemiology due to intercropping with maize, Boudreau, M., Mundt, C., 1992, Phytopathology, V. 82, pp. 1051-1060.

ABSTRACTS: We performed experiments to identify how maize influences bean rust (caused by Uromyces appendiculatus) in maize-bean intercrops. The effects of competition with maize and interference by maize on dispersal of rust urediniospores were evaluated in trials conducted three times during 1989 and 1990. Alterations in the nondispersal (infection) phase of the pathogen life cycle due to intercropping and
competition with maize also were assessed. Overall effects of maize on rust severity were evaluated in another experiment. Competition consistently steepened dispersal gradients (P < 0.10) in trials conducted more than 50 days after planting alone or in combination with interference (intercrop). Interference had no clear effect on dispersal gradients. Estimated total spore deposition per plot was increased (second trial) and decreased (third trial) by competition in both years (P < 0.05). Intercropping only affected infection once, in late 1989, when rust severity was reduced by 96% (P < 0.05). Overall disease was reduced by intercropping at two plot locations in both years (P = 0.07), but not at a third location. Bean leaf area declined because of competition in 1989 but not in 1990. Steep gradients may be due to increased spore escape, and microclimatic changes created by maize are probably responsible for the nondispersal effect.

Effects of plant populations and intercripping on the population patterns of bean flies on common beans, Karel, A., 1991, Environmental entomology, V. 20, pp. 354-357.

ABSTRACTS: Effects of four plant populations and intercropping beans with maize on the population patterns of bean flies (Ophiomyia phaseoli Tryon, O. centrosematis de Meijere, and Melanagromyza spencerella Greathead) on common beans were studied. Percentage of plants infested by bean Dies was
significantly less in the one-third beans and two-thirds maize intercrop combination than in pure stand beans. The incidence of bean flies decreased with increasing plant populations from 66,666 to 533,332 plants per ha. Ovipunctures made by bean flies in the leaves of beans were not significantly different among the various treatments. A significant and gradual decrease in the number of ovipunctures from lower to higher plant populations was recorded. The bean fly larva-pupal counts were significantly lower in both intercrop combinations than in pure stand beans; larval-pupal counts were significantly lower in higher
plant populations in 1983 season. Possible reasons for population patterns of bean flies are discussed.

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Helpful links for pest/crop interactions:

Agriforestry and insects of Africa

Comprehensive list of insect pests with descriptions

African forest-type distribution

African FAO representatives

Forests, trees and people of eastern Africa

Farmer to farmer information exchange in Kenya

Contact points for help in agriforestry in Africa

Help with locust control in Africa

IPM (integrated pest management) in Africa

Consultative group on international agriculture research. CGIAR's mission is to contribute to food security and poverty eradication in developing countries through research, partnership, capacity building, and policy support:

Helpful links for intercropping in Africa:

Crop diversity aids in deterring pests. Intercropping can also increase the resilience of the cropping system.

Mucuna spp., an aggressive Asian legume is a good African cover crop.
This site explains why, and gives some history and useable information
pertaining to cover crops in general:

Great Site for African Cover crop information:

A comprehensive list with good descriptions of various cover crops:

Up to date, species-specific descriptions of some cover crops and "green"
manure. Limited applicability due to it covering many regions, but a good

The Center for Cover Crops Information
and Seed Exchange in Africa:

Site offering new crop growing information to extension workers in
Africa, somewhat vague, but easy to maneuver and easy to get information
from: production demonstrations

This is a great photo-archive for african cover crops:

Good launchpad for answering questions about agroforestry in Africa:

Other useful links:

These links may offer additional assistance with African crops/pests/ or intercropping:

African agricultural research council. This offers insight into recent research and has peripheral links:

Great soil map of Africa, soil metadata:

EcoNews in Africa; a good start for various African ecological

Here are some discriptions of some staple African crops, and why they
are benefitial:


Subject on farming in Benin where these pests are common (it is in french!)


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Back to the FW571 Projects Page.

This webpage was created on April 27th, 2000