RA 00110.pdf - OAR@ICRISAT

Insect Pests of Pearl Millet in West Africa
and their Control
Mbaye NDoye 1 , and Ruparao Gahukar 2
Abstract
In the Sahelian zone of West Africa, several orders of insects infest pearl millet. They occur throughout the
region, however, pest incidence varies yearly from one location to another. Stem borers (Acigona ignefusalis,
Sesamia spp.) and the spike worm (Raghuva albipunctella) are apparently major pests under present
cropping conditions.
The ecology of the pests has been studied in some countries. Cultural techniques, insecticides, resistant
varieties, and natural enemies have been tested to reduce pest damage. The application of integrated pest
management strategies in subsistence agriculture requires further data on economic thresholds and
socioeconomic problems.
Introduction
Pearl millet (Pennisetum americanum) is a major
food crop of the West African Sahelian zone that
extends through eight countries: Cape Verde, Senegal,
Gambia, Mauritania, Mali, Burkina Faso, Niger,
and Chad (Fig. 1).
In this area, a wide range of pests, including birds,
insects, pathogenic fungi, and weeds are known to
attack pearl millet. Of these, insect pests are the most
injurious as reported by Risbec (1950) and Appert
(1957), and recently confirmed by NDoye (1979a).
Although millet parasites occur throughout the
Sahel, their specific incidence varies according to
rainfall and cropping patterns. For example, Sesamia
is present on late millets in high-rainfall regions,
but Acigona ignefusalis is found in relatively dry
areas.
The deficit rainfall conditions in the Sahel during
the last 15 years have led to increased pest incidence.
During the government consultation on the requirements
of the Sahel for crop and postharvest protection
(FAO 1976), it was unanimously agreed by the
delegates from the Sahelian countries that "several
economically unimportant pests have, during the
past few years, become a serious economic constraint
following the drought and subsequent return
to normal conditions. This is also partially due to
crop intensification and diversification and growing
of off-season crops."
Insect Pests of Pearl Millet
Seedling Pests
Pearl millet is planted during the dry season. The
crop emerges after the first rains, and seedlings are
exposed to a number of pests. Myriapod (Peridontopyge
spp.) attacks, especially in the early growth
stages, often require the crop to be replaced. The
grasshopper, Scapsipedus marginatus, cuts seedlings
at the base.
Fly infestation, particularly the shootfly Atherigona
soccata in late crops, occurs up to 5-6 weeks
after emergence. The larvae are responsible for
deadheart formation, which yellows and dries leaves.
In case of a late attack, the plant generates nonproductive
tillers.
Leaf beetles (Lema planifrons, Chaetocnema tibialis,
etc.) multiply on the leaves, feed on the epidermis
and parenchyma, and cause light colored spots
1. Institut Senegala is de Recherches Agricoles(ISR A), Centre National de la Recherches Agronomiques (CN R A), BP 51, Bambey, Senegal.
2. Project CILSS/FAO de Lutte integree S/C ISRA/Secteur Centre Sud, BP 199, Kaolack, Senegal.
ICRISAT (International Crops Research Institute for the Semi-Arid Tropics). 1987. Proceedings of the International Pearl Millet
Workshop, 7-11 April 1986, ICRISAT Center, India. Patancheru, A.P. 502324, India: ICRISAT.
195