Vapor heat treatment against Planococcus lilacinus Cockerell (Hemiptera:Pseudococcidae) on dragon fruit

BACKGROUND The coffee mealybug Planococcus lilacinus Cockerell, is an invasive pest that infests dragon fruit [Selenicereus undatus (Haworth) D.R. Hunt], that may require a phytosanitary treatment to meet quarantine requirements. In this study, vapor heat treatment was conducted to disinfest P. lilacinus on dragon fruit and the quality of dragon fruit was evaluated thereafter. RESULTS Adult female P. lilacinus was the most heat-tolerant stage at 47, 48 and 49 °C. The death kinetic model and probit model were used to predict LT99.9968 at the three temperatures. The treatment times predicted by the kinetic model that could effectively disinfest adult female P. lilacinus females were 120.84, 78.06 and 67.96 min at 47, 48 and 49 °C, respectively. In a confirmatory test of vapor heat treatment at 49 °C for 70 min, complete mortality was recorded for 33 195 adult females infesting 148 dragon fruits; thus, the efficacy level of disinfestation was 99.9910% at 95% confidence level. The quality of dragon fruit generally was not affected by heat treatment, fruit firmness was increased remarkably and respiration rate was significantly decreased. CONCLUSION Our result indicates that vapor heat treatment at 49 °C for a duration of 70 min is an effective phytosanitary treatment for control of P. lilacinus on dragon fruit that minimally impacts fruit quality.