Andamento della popolazione di Singhiella simplex su Ficus microcarpa nella città di Palermo.

Abstract

Singhiella simplex (Singh, 1931) (Hemiptera: Aleyrodidae) commonly called ficus whitefly, is an invasive species native to south-east Asia that mainly attacks ornamental plants of the genus Ficus, especially F. microcarpa L.f. and F. benjamina L., but can also infest other species, such as Hibiscus spp. (Malvaceae) or Mangifera indica L. (Anacardiaceae). After its introduction in the United States in 2007, the phytophagous spread to Central and South America and the Caribbean. In 2014, the Ficus whitefly was found in Cyprus and subsequently expanded to several Mediterranean countries, including Italy, where it significantly infests urban and peri-urban trees in several cities in Sicily and Calabria. At the end of 2023, a severe defoliation due to the ficus whitefly was reported on several street trees of Ficus microcarpa in Palermo. Therefore, a study was initiated to monitor the population trend of the insect pest in an area within the campus of the University of Palermo. Starting from May 2024, sampling was carried out every 10–15 days on 12 marked trees, collecting a branch of approximately 70 cm from each plant. Ten leaves from the apical part and ten leaves from the basal part were randomly taken from each branch. The sampled leaves were then examined in the laboratory, and the presence of eggs, nymphs, and pupae was recorded by classifying the number of stages into six abundance classes: 0, 0–25, 25–50, 50–75, 75–100, and >100. In addition, the number of S. simplex showing evident parasitisation was recorded for each leaf. The number of infested leaves remained low until mid-July, when a drastic increase in infestation was observed, reaching 100% of infested leaves by September. The presence of eggs, nymphs, and pupae on the leaves showed a similar trend, with a high percentage of leaves initially uninfested, followed by a rapid increase of the instars/leaf in the second half of July. Several predators were found during the various surveys, as well as the parasitoid Encarsia protransvena (Hymenoptera:Aphelinidae), but natural control remains insufficient to adequately control the whitefly infestations.