Location: Crop Improvement and Protection Research
Project Number: 2038-22430-001-02
Start Date: Oct 01, 2012
End Date: Sep 30, 2015
Codling moth and apple maggot eggs, larvae at different instars, and pupae will be subjected to oxygenated phosphine fumigations at low temperatures to determine the most tolerant stages. The most tolerant life stages will be further tested to determine an effective oxygenated phosphine fumigation treatment. The treatment will then be tested in large scale treatments with both insects and apples to verify its efficacy and evaluate impact on apple quality. Both codling moth and apple maggot will be reared on artificial diet and will also be reared on apples for fumigation treatments. Susceptibilities of codling moth and apple maggot on artificial diet and in apples to oxygenated phosphine fumigation treatments will be compared. A treatment which can control the most tolerant stage(s) of codling moth and apple maggot will be determined, and the treatment will then be further evaluated to determine impact of apple quality. Commercial apples of at least three varieties will be obtained from commercial packers, and fumigated in 442 liter metal chambers together with apples infested with codling moth and apple maggot at 1C in walk-in coolers. The chambers will be flushed with oxygen gas first to establish 50-60% O2, and then diluted pure phosphine at 1.6% from a compressed cylinder will be released into the fumigation chambers to conduct fumigation treatments. After fumigation treatments, infested apples will be incubated to allow any surviving insects to recover and commercial apples will be stored together with controls at 1C in a walk-in cooler. Infested apples with late larval instars will be dissected to examine larval mortality one day after fumigation. Apples with eggs and earlier instar larvae will be reared to allow any survivors to develop to late instars, and the apples will then be dissected to determine if there are survivors. Apple quality will be evaluated one month after fumigation. Apples from treatments and controls will be compared for visual appearance, flesh color, stain, and firmness. A color spectrum photometer will be used to measure color for apples with uniform colors. Skins of apples will be peeled off to evaluate flesh color. A potentiometer will be used to measure firmness of apple flesh.