The impact of biological control on pest survival and Aspergillus flavus in two stored maize genotypes

During storage, maize is attacked by various insect pests that damage its seeds and reduce their quality. A promising approach to control these pests is the use of natural enemies. However, there is limited knowledge about how natural enemies interact with different maize genotypes or generations. Additionally, the presence of storage pests often creates favorable conditions for Aspergillus flavus, one of the most common storage fungi. This study evaluates the biological control of three common storage pests: Sitotroga cerealella, Sitophilus zeamais, and Oryzaephilus surinamensis, by their respective natural enemies: Blattisocius tarsalis, Anisopteromalus calandrae, and Cephalonomia tarsalis. It examines how these biocontrol agents impact pest survival, kernel damage and A. flavus conidia count. These traits are compared across two commercial maize genotypes: a transgenic genotype expressing the insecticidal Cry1Ab protein and its non-transgenic near-isoline counterpart. Commercial seeds are used for both genotypes (F1), along with seeds obtained from field-grown transgenic and near-isoline plants (F2). Our findings demonstrated that natural enemies effectively reduced pest populations and pest-induced kernel damage, particularly in the F2 transgenic genotypes. The presence of A. flavus increased with kernel damage and rising pest populations; however, natural enemies suppressed fungal activity by reducing pest numbers, thereby improving kernel quality. Overall, these findings support the potential of an integrated pest management strategy combining transgenic resistance with biological control to manage pests and A. flavus, thus enhancing maize quality and safety during storage.