Performance of four major egg parasitoids as biocontrol agents against Spodoptera frugiperda (J. E. Smith)...

Parasitoids are effective biocontrol agents against Spodoptera frugiperda. Here, we studied four egg parasitoids (Trichogramma chilonis, Trichogramma pretiosum, Trichogrammatoidea bactrae, and Telenomus remus) on S. frugiperda eggs under laboratory conditions [25 ± 1 °C, 70 ± 5% RH, 14/10-h (L:D) photoperiod]. Then, Tr. chilonis (the best trichogrammatid species in the laboratory) was studied inside cages (1 m × 1 m) under maize-field conditions. Egg-to-adult periods (days) were recorded among different species, with Te. remus having the longest (10.00 ± 0.89 days) and Tr. bactrae the shortest (7.80 ± 0.66 days) periods. Furthermore, Te. remus exhibited the greatest adult longevity (days) for both males and females, with and without food. Lifespan parasitism under laboratory conditions was the highest for Te. remus (73.60 ± 7.23 eggs), followed by Tr. chilonis (45.40 ± 2.56 eggs) and Tr. pretiosum (42.00 ± 3.70 eggs). Adult emergence (%) was always higher than 90% and the sex ratio was higher than 0.60 for the studied egg parasitoid species. In the cage experiments set up in uncontrolled field conditions, different release densities of Tr. chilonis (50,000, 100,000, and 150,000 parasitoids/ha) were studied. Release densities of 100,000 and 150,0000 parasitoids per hectare were the most effective rates for managing S. frugiperda, with recorded egg parasitism of 71.36% and 72.88%, respectively. These findings provide crucial insights into the biological attributes and parasitism potential of these parasitoids, indicating the optimal release density of 100,000 Tr. chilonis/ha as an integrated pest management strategy against S. frugiperda in maize ecosystems.