Assessing the efficacy and generational stability of commercial transgenic maize resistance against key stored-product insect pests

Abstract

Genetic resistance, particularly through transgenic Bt maize, has demonstrated high efficacy in pest control under field conditions. However, in storage conditions, maize is susceptible to different pest species, which compromises its quality. It is unknown how effectively the Bt maize functions in storage environments or if resistance is being inherited in later generations. This study investigates two commercial maize genotypes: a transgenic genotype expressing the Cry1Ab protein and its near-isoline counterpart. It utilizes commercial seeds of both genotypes (F1), along with seeds obtained from field-grown transgenic and near-isoline plants (F2), which represent the seeds stored by farmers and the agricultural industry. The aim is to assess their vulnerability to common insect pests that affect stored products. By assessing grain damage and insect population dynamics, we identify differences in resistance among these different maize genotypes and generations. Our findings show that transgenic maize exhibits strong resistance against Sitotroga cerealella but lower resistance against Sitophilus zeamais. The impact of Oryzaephilus surinamensis on both genotypes was negligible. Additionally, the resistance diminishes in the F2 generation. With S. cerealella the F2 transgenic experienced 55% more damage compared to the F1. Similarly, in the case of S. zeamais, the F2 maize produced five times more frass than the F1, highlighting a significant reduction in resistance. This research identifies the resistance characteristics of maize, highlighting the most suitable traits for assessing pest resistance in stored maize. It emphasizes the need for sustainable pest control with genetic resistance, ensuring long-term protection of stored grains, and minimizing post-harvest losses.