Optimizing metabolic stress disinfection and disinfestation components to control Pseudococcus longispinus.

Metabolic stress disinfection and disinfestation (MSDD) has been demonstrated to effectively control longtailed mealybug, Pseudococcus longispinus (Targioni Tozzetti). Standard components previously used for testing MSDD system included a 30-min physical phase of short cycles pressure changes followed by a 60-min chemical phase using ethanol vapor at 10 kPa. This study investigated the effect of varying the following MSDD components on mealybug mortality: duration of the physical and chemical phases, ethanol concentration, and extent of vacuum during the chemical phase. Mealybug mortality responses were analyzed, and the components were optimized using binary logistical regression to achieve 99% mortality of three life stages of the longtailed mealybug (adults, second- and third-instar nymphs and crawlers). Data indicated that the optimal components to achieve 99% mortality of all life stages were a 30-min physical phase and a 45-min chemical phase with 275 mg/liter ethanol at 30 kPa. Optimized components were obtained using binary logistical regression models. These optimized components yielded a 15-min reduction in total treatment time and a 20-kPa decrease in pressure during the chemical phase. Achievement of optimal insecticidal efficacy required all four MSDD components. Nevertheless, optimization and validation achieved 17 and 22% reductions in duration of treatment time and extent of vacuum, respectively.