Effect of artificial and natural diets on the morphometrics and biology of Sesamia inferens (Walker) (Lepidoptera: Noctuidae)

Sesamia inferens is a polyphagous pest severely impacting gramineous crops (e.g., rice, wheat, maize) across Asia, causing "dead heart" and "white ear" damage. Originally a minor pest, it has escalated into a major threat to cereal production and food security. This study compared the effects of an artificial diet (Siddiqui et al., 1983 formulation) versus a natural maize-based diet on the pest’s morphometrics and biology under controlled conditions (28 ± 2 °C, 75–85% RH). The goal was to evaluate diet suitability for mass rearing and inform sustainable management strategies. Eggs from females reared on an artificial diet were slightly larger (0.21 × 0.11 mm) than those from females on a natural diet (0.19 × 0.10 mm), while egg clusters were larger on the natural diet (145.4 vs. 134.6 eggs). Larvae fed on the artificial diet showed marginally faster growth and greater size across all instars. Pupae from the artificial diet were larger and heavier (female pupae: 14.69 mm, 142.20 mg) than those from the natural diet (14.13 mm, 140.60 mg). The larval period was shorter on the artificial diet, ranging from 26 to 35 days (mean 30.3 days), versus the natural diet from 27 to 39 days (mean 32.7 days). Adults reared on the artificial diet were slightly larger, but had reduced longevity (males 5.8, females 7 days) compared to natural diet counterparts (males 6.2, females 7.9 days). Overall, the life cycle was shorter on the artificial diet (60.7 days) than on the natural diet (65.25 days). An artificial diet for S. inferens effectively supports its complete life cycle, promotes faster development, and results in a larger body size compared to a natural maize diet, making it ideal for laboratory mass-rearing and experiments requiring uniform cohorts. In contrast, rearing on a natural diet maintains higher fecundity per egg cluster and longer adult lifespan, highlighting traits important for ecological relevance and potential field performance.