Morphometric Analysis of Fall Armyworm (Spodoptera frugiperda) Larvae Reared on Different Diets

Spodoptera frugiperda (fall armyworm) is a major pest in many African and Asian countries, severely affecting global agriculture, especially maize, a key staple crop. To evaluate various biological agents for their control, continuous rearing of this economically important pest under laboratory conditions becomes necessary. Accordingly, this study assessed the growth and development of S. frugiperda larvae reared on five artificial diets (D1: chickpea-based, D2: Wheat-based, D3: Soybean-based, D4: Bean-based, D5: Cowpea-based) compared to a natural maize leaf diet (D6, control). The experiment was conducted under controlled conditions (25 ± 2°C, 65 ± 10% RH, 12:12 h light-dark cycle). The key morphometric parameters, such as head capsule width and length, larval and pupal length, breadth, and weight, as well as adult body length and wingspan for both sexes, were recorded. Significant differences were observed vis-a-vis the diets. The chickpea-based diet (D1) showed the best results, producing the heaviest pupae (average 168.36 mg) and the highest values in all morphometric traits. These findings highlight the potential of the D1 diet as a more effective and efficient option for laboratory rearing of S. frugiperda, facilitating advanced research and large-scale evaluation of biological control agents that could be used in any integrated pest management strategies..