Home > Constraints


Insect Problems and Cowpea

Cowpea suffers heavily from insects, both in the field as well as when the grain is stored after harvest. Graphic proof of this comes from comparing yields with and without insecticide treatments:

Insecticide Formulation Application Rate(kg/ha) Yield (kg/ha)
Carbaryl 85% w.p. 1.12 1382
Endosulfan 35% e.c. 0.43 1674
DDT/BHC 20%/2% e.c. 1.0 1599
Unsprayed     76
from A.K. Raheja U.l.v. spraying for cowpea in northern Nigeria (1976) PANS 22, 327-332.

Clearly, yield reductions due to insects are tremendous, commonly reaching as high as 95 percent, depending upon the location, year, and cultivar. In fact, a great many cowpea growers in Africa don't use insecticides, can't obtain them, or can't afford them, don't have the necessary equipment, or don't know how to apply them properly. Conventional insecticides are not the answer to the insect problems.

Insects continue to damage cowpeas after harvest. The major pest is the cowpea weevil. A single cowpea weevil female can reproduce herself 20-fold every 3-4 weeks. Cowpea grain that has a very light infestation - which starts in the field before it is stored - will have a heavy infestation within two or three months. Foods prepared with this grain have an unpleasant flavor. If taken to market, the price of this grain is discounted.



Website hosted by:
Purdue University
Department of Entomology
901 W. State Street
West Lafayette, IN 47907-2089
(765) 494-4554
© 2010 Purdue University | An equal access/equal opportunity university | Copyright Complaints
If you have trouble accessing this page because of a disability, please contact Webmaster at