Parasitization Activity by Eretmocerus iulii over the Orange Spiny Whitefly, Aleurocanthus spiniferus, in Sicily.

Since its first report in 2020, Aleurocanthus spiniferus has rapidly spread in Sicily, causing alarm among citrus growers. To assess biocontrol possibilities, its spontaneous natural enemies were observed and, from summer 2023, sporadic parasitization was noted by an unknown species of the genus Eretmocerus, recently described as E. iulii. Parasitization over the OSW was studied regularly from November 2023 at two sites and from August 2024 at a third site (all of them in eastern Sicily). At the first two sites, parasitization was very low (<1%) at the beginning of the observations, increased during autumn 2023 (not exceeding 10%), decreased during winter 2023-2024 and rapidly increased again during spring 2024, peaking in May-June with over 30%. After declining during the hot and dry summer 2024, parasitization increased again in autumn 2024, reaching 15-20% higher values compared to the previous autumn, and continued to rise gradually until the end of the monitoring period. A similar parasitization trend was noted at the third site. At all three sites, increasing parasitization coincides with a lower density of OSW nymphs. These findings show the potential of E. iulii as a promising biological control agent, offering a sustainable solution to mitigate the effect of this whitefly on citrus production in Sicily.