Insects are a major factor in the low yields of African cowpea crops, and they affect each tissue component and developmental stage of the plant.
In bad infestations, insect pressure is responsible for over 90% loss in yield.
The legume pod borer, Maruca vitrata, is the main preharvest pest of the cowpea.
Other important pests include pod sucking bugs, thrips, and the postharvest cowpea weevil, Callosobruchus maculatus.

M. vitrata causes the most damage to the growing cowpea due to their large host range and cosmopolitan distribution.
It causes damage to the flower buds, flowers, and pods of the plant, with infestations resulting in a 20–88% loss of yield.
While the insect can cause damage through all growth stages, most of the damage occurs during flowering.
Biological control has had limited success, so most preventive methods rely on the use of agrichemicals.
Genetically modified cowpeas are being developed to express the cry protein from Bacillus thuringiensis, which is toxic to lepidopteran species including the maruca.

Severe C. maculatus infestations can affect 100% of the stored peas and cause up to 60% loss within a few months.
The weevil generally enters the cowpea pod through holes before harvest and lays eggs on the dry seed.
The larvae burrow their way into the seed, feeding on the endosperm.
The weevil develops into a sexually mature adult within the seed.
An individual bruchid can lay 20–40 eggs, and in optimal conditions, each egg can develop into a reproductively active adult in 3 weeks.
The most common methods of protection involve the use of insecticides, the main pesticides used being carbamates, synthetic pyrethoids, and organophosphates.

Cowpea is susceptible to nematode, fungal, bacterial, and virus diseases, which can result in substantial loss in yield.
Common diseases include blights, root rot, wilt, powdery mildew, root knot, rust and leaf spot.
The plant is susceptible to mosaic viruses, which cause a green mosaic pattern to appear in the leaves.
The cowpea mosaic virus (CPMV), discovered in 1959, has become a useful research tool.
CPMV is stable and easy to propagate to a high yield, making it useful in vector development and protein expression systems.
One of the plant's defenses against some insect attacks is the cowpea trypsin inhibitor (CpTI).
CpTI is the only gene obtained outside of B. thuringiensis that has been inserted into a commercially available genetically modified crop.

Besides biotic stresses, cowpea also faces various challenges in different parts of the world such as drought, heat, and cold.
Drought lowers the growth rate and development, ultimately reducing yield, although cowpea is considered more drought tolerant than most other crops.
Drought at the preflowering stage in cowpea can reduce the yield potential by 360 kg/ha.
Crop wild relatives are the prominent source of genetic material, which can be tapped to improve biotic/abiotic tolerance in crops.
International Institute of Tropical Agriculture (IITA), Nigeria and Institut de I’Environment ae de Recherches Agricoles are working on cowpea crop wild relatives to tap the genetic diversity and transfer that into cultivars to make them more tolerant to different stresses and adaptive to climate change.
Insects are a major factor in the low yields of African cowpea crops, and they affect each tissue component and developmental stage of the plant. In bad infestations, insect pressure is responsible for over 90% loss in yield. The legume pod borer, Maruca vitrata, is the main preharvest pest of the cowpea. Other important pests include pod sucking bugs, thrips, and the postharvest cowpea weevil, Callosobruchus maculatus.
M. vitrata causes the most damage to the growing cowpea due to their large host range and cosmopolitan distribution. It causes damage to the flower buds, flowers, and pods of the plant, with infestations resulting in a 20–88% loss of yield. While the insect can cause damage through all growth stages, most of the damage occurs during flowering. Biological control has had limited success, so most preventive methods rely on the use of agrichemicals. Genetically modified cowpeas are being developed to express the cry protein from Bacillus thuringiensis, which is toxic to lepidopteran species including the maruca.
Severe C. maculatus infestations can affect 100% of the stored peas and cause up to 60% loss within a few months. The weevil generally enters the cowpea pod through holes before harvest and lays eggs on the dry seed. The larvae burrow their way into the seed, feeding on the endosperm. The weevil develops into a sexually mature adult within the seed. An individual bruchid can lay 20–40 eggs, and in optimal conditions, each egg can develop into a reproductively active adult in 3 weeks. The most common methods of protection involve the use of insecticides, the main pesticides used being carbamates, synthetic pyrethoids, and organophosphates.
Cowpea is susceptible to nematode, fungal, bacterial, and virus diseases, which can result in substantial loss in yield. Common diseases include blights, root rot, wilt, powdery mildew, root knot, rust and leaf spot. The plant is susceptible to mosaic viruses, which cause a green mosaic pattern to appear in the leaves. The cowpea mosaic virus (CPMV), discovered in 1959, has become a useful research tool. CPMV is stable and easy to propagate to a high yield, making it useful in vector development and protein expression systems. One of the plant's defenses against some insect attacks is the cowpea trypsin inhibitor (CpTI). CpTI is the only gene obtained outside of B. thuringiensis that has been inserted into a commercially available genetically modified crop.
Besides biotic stresses, cowpea also faces various challenges in different parts of the world such as drought, heat, and cold. Drought lowers the growth rate and development, ultimately reducing yield, although cowpea is considered more drought tolerant than most other crops. Drought at the preflowering stage in cowpea can reduce the yield potential by 360 kg/ha. Crop wild relatives are the prominent source of genetic material, which can be tapped to improve biotic/abiotic tolerance in crops. International Institute of Tropical Agriculture (IITA), Nigeria and Institut de I’Environment ae de Recherches Agricoles are working on cowpea crop wild relatives to tap the genetic diversity and transfer that into cultivars to make them more tolerant to different stresses and adaptive to climate change.
Cowpea