Florida red scale Chrysomphalus aonidum (Hemiptera: Diaspididae) and parasitoid Aphytis melinus (Hymenoptera: Aphelinidae) colonization of Citrus Under Protective Screen

Abstract The Citrus Under Protective Screen is a novel production system implemented to grow citrus free of huanglongbing disease vectored by Asian citrus psyllid, Diaphorina citri. Other significant pests such as mites, scales, thrips, mealybugs, and leafminers, as well as parasitoids and small predators, have been identified from Citrus Under Protective Screen and require management. Chrysomphalus aonidum (L.), an armored scale is a major pest of citrus. We determined the incidence of C. aonidum and parasitoid Aphytis melinus in 4-quarter-acre Citrus Under Protective Screen structures and open-air controls planted with grapefruit (Citrus paradisi). The greatest difference between the 2 production systems in temperature and humidity was observed using daily maximum values. Except for 2 of the 26 mo of study, the maximum daily temperature was significantly higher in the Citrus Under Protective Screen than in open-air, ranging from −0.6 to 16.1 °C. The maximum relative humidity between the 2 systems averaged 91% to 99%. C. aonidum was exclusively found in the in-ground trees in the Citrus Under Protective Screen, infesting 11% to 12% of trees from 2020 to 2022. The density of C. aonidum increased from 2020-2021 to 2021-2022 sampling cycle, averaging 7.81/cm2 and 15.55/cm2 on the leaves, respectively, and 3.09/cm2 and 5.63/cm2 on fruit, respectively. A. melinus captures on the yellow sticky cards were significantly higher in the Citrus Under Protective Screen than in open-air. Significantly higher numbers of C. aonidum were parasitized on leaves than on fruit, averaging 19% to 23% and 0.78% to 1.53%, respectively. Findings suggest the risk of C. aonidum infestation and prospects for biological control in Citrus Under Protective Screen.