Managing Diaphorina citri and Nipaecoccus viridis with individual protective covers (IPCs) and insecticides in young citrus

Diaphorina citri Kuwayama (Asian citrus psyllid) is the principal vector of Candidatus Liberibacter asiaticus, the bacterium associated with huanglongbing, a destructive disease threatening citrus industries worldwide. Effective management of D. citri is critical. Individual Protective Covers (IPCs) placed over young citrus trees exclude D. citri but may also prevent access by natural enemies, potentially enabling secondary pests like Nipaecoccus viridis Newstead to proliferate. This study investigated the seasonal infestation dynamics of N. viridis under IPCs and evaluated the efficacy of eight insecticides, both conventional and mycoinsecticides, against N. viridis and D. citri in IPC-protected trees and under laboratory conditions. In the field experiments, terminal shoots and leaves were collected from treated trees to assess N. viridis infestations. Residual effects on D. citri were tested by placing lab-reared adults on treated field-aged leaves from IPCs. Additional lab bioassays evaluated the insecticidal effects on both pests. Field data revealed that N. viridis populations increased under IPCs from November through April, often causing dieback. All treatments reduced mealybug numbers relative to control. In lab assays, Sivanto Prime, Sivanto SL300, and Lalguard M52 caused 100% mortality of mealybug immatures and adults, and the others ranged from 62–94%. D. citri mortality from treated leaves peaked in the first week and declined over time. Admire Pro, Botanigard, BoteGHA, Isarid, Lalguard, Sivanto Prime, and Sivanto SL300 induced 100% ACP mortality in lab bioassays. These preliminary results highlight the role of insecticides in managing D. citri and secondary pests under IPCs within an integrated pest management system.