An assessment of the risk of Bt-cowpea to non-target organisms in West Africa

Abstract

Cowpea (Vigna unguiculata Walp.) is the most economically important legume crop in arid regions of sub-Saharan Africa. Cowpea is grown primarily by subsistence farmers who consume the leaves, pods and grain on farm or sell grain in local markets. Processed cowpea foods such as akara (a deep-fat fried fritter) are popular in the rapidly expanding urban areas. Demand far exceeds production due, in part, to a variety of insect pests including, in particular, the lepidopteran legume pod borer (LPB) Maruca vitrata. Genetically engineered Bt-cowpea, based on cry1Ab (Event 709) and cry2Ab transgenes, is being developed for use in sub-Saharan Africa to address losses from the LBP. Before environmental release of transgenic cowpeas, the Bt Cry proteins they express need to be assessed for potential effects on non-target organisms, particularly arthropods. Presented here is an assessment of the potential effects of those Cry proteins expressed in cowpea for control of LPB. Based on the history of safe use of Bt proteins, as well as the fauna associated with cultivated and wild cowpea in sub-Saharan Africa results indicate negligible effects on non-target organisms. Keywords Cowpea • Maruca vitrata • Bt-cowpea • Non-target organisms • West Africa • Environmental risk • Assessment • Arthropod fauna Key messages • Data on the environmental safety of Bacillus thuringiensis (Bt) Cry proteins, especially toward non-target arthropods, are available for many genetically modified crops but not in the contest of cowpea. • Before environmental release of Bt-cowpea for control of the legume pod borer, a major insect pest attacking cowpea, the potential effects on non-target organisms (NTO), particularly arthropods, need to be assessed. • An assessment of the Bt Cry proteins, their history of safe use, as well as the fauna associated with cultivated and wild cowpea in sub-Saharan Africa indicates negligible effects on non-target organisms.

Study of Productivity and Economic Evaluation of Intercropping Cowpea With Maize Under Three Irrigation Water Levels and Their Response to Insect Infestation and Viral Infection

“…In Egypt, cowpea is promising double purpose forage and seed crop for its green canopy or using it in animal diets as dry seeds, as well as it is a primary source of plant protein for humans and animals in the summer season (HamdAlla et al, 2014). It is the most economically important legume crop in arid regions of sub-Saharan Africa (Ba et al, 2018). However, Singh and Allen (1979) reported that major insect pests of cowpea that cause economic losses are cowpea aphids (Aphis craccivora Koch), leafhoppers (Empoasca spp.…”

A detached leaf assay for testing transient gene expression and gene editing in cowpea (Vigna unguiculata [L.] Walp.)

“…Most cowpea genotypes are highly susceptible to Maruca vitrata, a pod borer which devastates crop yields and naturally resistant germplasm has not been identified. Maruca-resistant cowpea varieties containing the Bacillus thuringiensis (BT) gene have now been developed for Nigerian agricultural production, providing a transgenic platform for cowpea crop improvement [1].…”

Natural Pest Regulation and Its Compatibility with Other Crop Protection Practices in Smallholder Bean Farming Systems

“…Plant-incorporated protectants (PIPs) are biopesticides such as the gene encoding the Bt toxin that can be introduced into the plant genome that allows the plant to produce this toxin and increases the resistance of the plant to some pests [ 178 ]. For instance, the Cry proteins expressed in Bt cowpeas have shown a less negative effect on nontarget organisms [ 179 ]. Generally, the PIPs available globally for the specific management of M. vitrata and A. fabae are limited, and equally, their impacts on their natural enemies have not been studied; thus, more work has to be done to address this gap.…”