D3358: Efficacy of systemic insecticides in managing citrus mealybug in the greenhouse

Citrus mealybug, Planococcus citri (Risso) (Hemiptera: Pseudococcidae), is a polyphagous, sap-sucking pest that has become increasingly problematic in California citrus. Feeding damage results in leaf and fruit yellowing and reduced tree vigor, while honeydew excretion promotes sooty mold development, affecting fruit quality. A greenhouse study was conducted on two-year-old potted ‘Tango’ mandarin (Citrus reticulata Blanco) plants at the Lindcove Research and Extension Center, Exeter, CA, to evaluate the efficacy of four systemic insecticides against P. citri. Treatments included Sivanto 300 SL (flupyradifurone), Spidoxamat, Sivanto Prime, Admire Pro (imidacloprid), and an untreated control. The experiment followed a completely randomized design with four replicates per treatment. In 2024, applications were made on 1 July, and P. citri counts were conducted on whole plants before and for four weeks after treatment. The trial was repeated in 2025 with applications on 12 February and assessments based on 30-cm twigs. All insecticide treatments significantly reduced P. citri densities compared to the untreated control in both years (P < 0.05). In 2024, Admire Pro resulted in the lowest posttreatment mean (0.3 mealybugs/plant), compared to 33.5 mealybugs/plant in the untreated control. In 2025, Admire Pro maintained significantly lower populations through six weeks of posttreatment. Results are discussed in the context of using systemic insecticide application for managing mealybugs in citrus and provide a basis for future field validation for season long control.