Low-Temperature Storage as a Postharvest Treatment to Control Pseudococcus affinis (Homoptera: Pseudococcidae) on Royal Gala Apples

Abstract

Royal Gala apples infested by the obscure mealybug, Pseudococcus affinis (Maskell), were stored at 0, 4, and 7 ± 0.5°C for various durations from 0 (control) to 126 d. As storage temperature decreased, the estimated times for 50 and 99% P. affinis mortality (LT50 and LT99, respectively) decreased. Mean LT50 values for the different life stages tested increased in the following order: 1st instar < 2nd-3rd instar ≤ female adult. This LT50 pattern became more evident with increasing temperature. At both 4 and 7°C, mean 1st-instar LT99 values were less than those for 2nd-3rd instars and female adults. Storage at 0°C resulted in the lowest mean LT99S for 1st instars, 2nd-3rd instars, and female adults (16.1, 19.0, and 18.9 d, respectively). A large-scale test storing 6,403 1st instars, 3,050 2nd-3rd instars, and 3,028 female adults at 0°C for 42 d resulted in complete mortality.