POSTHARVEST DISINFESTATION OF LIGHTBROWN APPLE MOTH AND LONGTAILED MEALYBUG ON PERSIMMONS USING HEAT AND COLD

The effect of temperature on the mortality responses of fifth instar l ightbrown apple moth (Epiphyas postvittana Walker) and longtailed meal ybug (Pseudococcus longispinus Targioni-Tozetti) on 'Fuyu' persimmons was examined at temperatures between 44 and 50 degrees C (hot air), an d 0 and 7 degrees C (cold storage). P. longispinus was more tolerant t han E. postvittana to heat treatments but tolerance was opposite in co ld storage. For both species, cold storage following heat treatment al lowed a reduction in time of heat treatment required for a predicted 9 9% mortality level. This effect was most apparent at 0 degrees C and l ess with higher cold storage temperatures. E. postvittana was more tol erant than P. longispinus to the combination treatment. An estimated t reatment time of 3.3 h (including a 2 h warming-up period) at 44 degre es C, followed by 40 days cold storage at 0 degrees C was needed to ac hieve 99% mortality of E. postvittana. Time required to give 99% morta lity decreased with increasing high temperature to about 2.6 h (includ ing a 2 h warm-up period) at 50 degrees C, followed by similar cold st orage conditions. Treatment for 5 h at 47 degrees C followed by cold s torage at 0 degrees C may delay chilling injury in persimmons while ca using only minor levels of heat injury to the fruit. A combined heat/c old storage treatment may therefore be effective for disinfestation of E. postvittana and P. longispinus on persimmons. (C) 1997 Elsevier Sc ience B.V.