Alfalfa as cover crop enhances predators and biological control of the Mediterranean fruit fly in a citrus orchard

Abstract

The growth of functional plants that support beneficial arthropods within citrus, Citrus sinensis L., orchards may significantly improve the management of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann). This research conducted over three years (2020–2023) evaluated the consequences of sowing alfalfa, Medicago sativa L., as a cover crop (Cp plots) compared with bare ground (Bp) in a citrus orchard on the medfly populations and their tree- and ground-dwelling predators. Each year, the study was conducted from October 16th to December 11th. The number of medfly adults/trap/week decreased in the Cp plots compared to the Bp plots during 2021 and 2022. A significant reduction in the number of larvae/fruit and the percentage of infested fruits was seen in Cp plots compared with Bp plots in 2021 and 2022. The total abundance of tree- or ground-dwelling predators was higher in Cp plots than in Bp plots. In addition, Cp plots enhanced the Shannon diversity index for tree-dwelling predators and ground-dwelling predators compared with Bp plots. Therefore, planting alfalfa as a functional cover crop in citrus orchards offers a practicable strategy for reducing medfly populations in integrated pest management.