From laboratory to field: Performance and interaction dynamics of Telenomus remus and Trichogramma pretiosum for biological control of lepidopteran maize pests

• Telenomus remus outperformed Trichogramma pretiosum on Spodoptera frugiperda eggs. • T. remus outperformed T. pretiosum on Helicoverpa armigera eggs. • T. remus exhibited a positive density-dependent response. • T. remus had no negative influence from competition with T. pretiosum . Biological control using egg parasitoids is a key strategy for integrated management of lepidopteran pests in large-scale cropping systems. Among these parasitoids, Trichogramma pretiosum and Telenomus remus are widely employed in maize, especially in the Neotropics and Asia. However, their field release raises questions about their potential interactions and the overall effectiveness of both parasitoids. This study aimed to evaluate the performance and interaction dynamics of T. remus and T. pretiosum from laboratory to open-field conditions. Five experiments were conducted: (1) host preference of T. pretiosum and (2) T. remus between Spodoptera frugiperda and Helicoverpa armigera eggs; (3) parasitism capacity (individual and combined); (4) interaction (different densities and release timings); and (5) field releases (individual and combined, using natural and sentinel egg masses). Telenomus remus outperformed T. pretiosum across all experimental conditions, with higher parasitism rates and no negative influence from competition or interspecific presence. When both species were released together in the field, T. remus accounted for nearly all observed parasitism, with minimal contribution from T. pretiosum, a pattern consistent with laboratory findings. Under high-density conditions, T. remus exhibited a positive density-dependent response, whereas T. pretiosum showed reduced performance, likely due to mutual interference. Therefore, the use of T. remus as a commercial biocontrol agent can be adopted not only for managing fall armyworm but also for other lepidopteran pests in maize cropping systems, for instance, H. armigera, due to its promising parasitism.