Establishing Biological Control in Citrus Under Protective Screen Production Systems: Florida Red Scale and Aphytis melinus Interaction
Posted August 2025
Researchers: Jawwad Qureshi, Salman Al-Shami, Mark A. Ritenour, Arnold Schumann
Contact: Jawwad Qureshi, UF/IFAS SWFREC jawwadq@ufl.edu
Summary:
The citrus under protective screen (CUPS) is a novel production system implemented to grow citrus free of huanglongbing vectored by the Asian citrus psyllid. Other significant pests such as mites, scales, thrips, mealybugs, and leafminers, as well as parasitoids, and small predators have been identified from CUPS. Chrysomphalus aonidum (L.), an armored scale is a major pest of citrus. We determined the incidence of C. aonidum and parasitoid, Aphytis melinus in four-quarter acre CUPS structures and open-air (OA) controls planted with grapefruit (Citrus paradisi). Temperature and humidity were higher in CUPS than in OA. Chrysomphalus aonidum was not found in OA plantings and was exclusively found in the in-ground plantings in the CUPS, where 11- 12% trees were infested between two years of sampling cycles. The density of C. aonidum on the leaves increased significantly from 7.8 to 15.6 scales per cm2 from the first to second sampling cycle. Fruit infestation per infested tree averaged 18-24% with 3.1- 5.63 scales per cm2. Aphytis melinus was detected on the yellow sticky traps in CUPS and OA, and parasitized C. aonidum on leaves and fruit in the CUPS. Aphytis melinus captures were significantly higher in the CUPS than in OA and decreased with increasing temperature. The parasitism on leaves was remarkably higher than on fruit averaging 21% and 1.2%, respectively. Findings suggest the risk of C. aonidum infestation and prospects for biological control in CUPS.
Take Home Message:
- CUPS protects from ACP and HLB. However, mites, scales, thrips, mealybugs, and leafminers were identified.
- Findings of parasitoids and predators suggest potential for biological control.
- Monitoring is critical to identify pest problems and make informed management decisions.
