Influence of Adult Diet and Cold Storage on the Biological Performance of Telenomus remus Nixon (Hymenoptera: Scelionidae) Against Spodoptera frugiperda (J.E. Smith)

Abstract

The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a globally invasive pest posing serious threats to maize production. Augmentative biological control using the egg parasitoid Telenomus remus Nixon has emerged as a sustainable management strategy. The present study evaluated the influence of different adult feeding diets and cold storage duration on the biological performance of T. remus under laboratory conditions (25 ± 2 °C, 70 ± 5% RH, 14 h photoperiod). Four adult diets-honey, honey + water (1:1), probiotic diet, and a standard fall armyworm adult diet-were assessed for their effects on longevity, parasitism, adult emergence, and sex ratio of T. remus parasitoids. Honey and probiotic diets significantly enhanced parental parasitism (80.70 and 79.20 eggs, respectively), female longevity (6.70 and 6.40 days), and F1 total parasitism (115.60 and 108.40 eggs), compared to other treatments. Adult emergence remained high (>96%) across diets, but the female-biased sex ratio was greatest in honey-fed parasitoids (0.78). Cold storage studies revealed that parasitized eggs stored at 4 °C for up to five days maintained high adult emergence (96.67-99.33%), comparable to the control. However, emergence declined sharply beyond five days, dropping below 55% after seven days. The results demonstrate that carbohydrate-rich diets, particularly honey, significantly improve the immediate and transgenerational fitness of T. remus, while short-term cold storage (≤5 days) preserves parasitoid quality. These findings provide practical insights for mass rearing, storage, and field-release programs aimed at the sustainable management of S. frugiperda using T. remus egg parasitoids.