Ground-covers affect the activity density of ground-dwelling predators and their impact on the Mediterranean fruit fly, Ceratitis capitata

Three developmental stages of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), can be found in the soil (late third instar larvae, pupae, and teneral adults). These stages are susceptible to predation by generalist ground-dwelling predators. Our objectives have been to investigate the association between ground cover management (bare soil, a seeded cover of Festuca arundinacea and a mulch of straw), the emergence success of C. capitata , and the activity density of the most important groups of ground-dwelling predators (spiders, beetles, ants and earwigs). As expected, C. capitata emergence was lower in a seeded cover of Festuca arundinacea (FA) and a mulch of straw (M) (10.2%) relative to bare soil (BS) (13.2%). This was related to higher diversity and activity density of ground-dwelling predators in FA and M compared to BS. The contribution of the ground-dwelling predators considered in this study to this reduction highlights the key role of beetles, earwigs and, to a lesser extent, ants, while the contribution of the most abundant group of ground-dwelling predators, spiders, remains unclear. Ground covers appear as a strong and sustainable conservation biological control method that should be taken into consideration for the management of C. capitata populations.