Sustainable management of pests and improved yield in Chinese cabbage (Brassica rapa subsp. chinensis) by Black soldier fly frass and Desmodium under Wonder multistory gardens

Intensive use of inorganic fertilizers and pesticides in farming to improve productivity has globally destroyed soil fertility, interfered with biodiversity, and negatively affected both human and the environment. To overcome these problems, it is very important to shift our attention towards eco-friendly alternatives like insect-based black soldier fly frass (BSFF) and Desmodium that have the potential to increase crop growth and yield as well as control or suppress pests sustainably. Black soldier fly frass fertilizer with its rich plant growth nutrient not only improves the growth and yield of crops but also offers protection to pests through the provision of nutrients; also, the chitin present helps control pests. Desmodium also has tremendous potential to protect plants from pests when used as a companion crop as it increases the diversity and activity of natural enemies, which helps to suppress pests. In this study, we examined the potential of Desmodium and BSFF in the management of common brassica pests and improved growth under low-cost vertical gardens suitable for urban settings. A Randomized Complete Block design trial on wonder multistorey gardens with eight treatments was laid out as sole cabbage (T0), Powdered black soldier fly frass (T1), liquid black soldier fly frass, (T2), Desmodium (T3), NPK (T4), combined powdered black soldier fly frass with Desmodium (T5), combined liquid black soldier fly frass with Desmodium (T6)) and combined NPK with Desmodium (T7), each of which was replicated three times. Data collected on pests’ numbers, growth parameters, damage score and yield showed significant differences when subjected to ANOVA. Gardens where BSFF and Desmodium were used showed a high growth rate and yield, and reduced pest damage. This indicated the potential of BSFF and Desmodium as an alternative source of plant nutrients and as a pest control strategy in vertical vegetable production systems.