Increases in Florida Red Scale Populations through Pesticidal Elimination of Aphytis holoxanthus Debach in Florida Citrus

Based on a laboratory study, a field study was designed to determine if the host–parasite relationship of Florida red scale and Aphytis holoxanthus could be disrupted in Florida by carbaryl and dicofol pesticide applications. The mean survival rate of third instar nymphs and gravid females on leaf samples was higher in the carbaryl treatment than in the dicofol and control treatments due to lower rates of parasitism. There were no significant differences in the survival of third instar nymphs and gravid females in the dicofol and control treatments. In September, parasitism of Florida red scale was significantly higher in the control and dicofol treatments than in the carbaryl treatment, and September fruit infestation by Florida red scale was highest in the carbaryl treatment, followed by those in the dicofol and control treatments. Higher fruit infestation in the carbaryl treatment (26%) than in the dicofol (9%) and control (7%) treatments did not result in higher fruit drop. This is the first Florida study that shows that pesticide use can increase Florida red scale populations and it confirms previous laboratory results.