Field Performance of a Genetically Modified Cowpea (<i>Vigna unguiculata</i>) Expressing the Cry1Ab Insecticidal Protein Against the Legume Pod Borer <i>Maruca vitrata</i>

Abstract

Cowpea (Vigna unguiculata) is a vital crop in sub-Saharan Africa, but the legume pod borer (LPB), Maruca vitrata, can cause over 80% yield losses. Natural resistance to this lepidopteran pest is absent in cowpea germplasm, and insecticides are ineffective due to the pest’s cryptic behavior. To address this, a genetically modified (GM) cowpea expressing the cry1Ab protein from Bacillus thuringiensis (Bt) was developed, providing complete LPB resistance. This Bt cowpea, commercialized as Sampea 20-T in Nigeria, was recently approved in Ghana as Songotra T. To evaluate its performance and the financial returns of its cultivation, field trials were conducted across multiple locations in northern Ghana to compare it to the non-transgenic Songotra control and two commercial cultivars, Kirkhouse-Benga and Wang-Kae. Songotra T exhibited protection against LPB infestations and damage, achieving a grain yield of 2534 kg/ha compared to 1414–1757 kg/ha for the other entries. As expected, non-LPB pest infestations and damage were similar across all entries. Economic analysis revealed that Songotra T had the highest return on investment (464%), outperforming the other tested cultivars (214%). These results demonstrate the potential of GM crops to enhance yields and profitability for resource-poor farmers, underscoring the value of biotechnology for addressing critical agricultural challenges.

Keywords

• <i>cry1Ab</i> gene
• genetic modification
• grain yield
• pest damage
• return on investment