1a. Objectives (from AD-416):
Trade barriers exist on the import of apples and cherries from the Pacific Northwest based on the presumed risk of temperate fruit flies entering and establishing in export market countries. A multi-faceted or systems approach taking into account potential fly distribution, fly detection, and fly identification components are addressed in this project. In this project we plan to evaluate potential fly distributions through modeling, evaluate attractants for flies, evaluate methods to discriminate closely related fly species, and to develop collaborations for modeling risk of infestations in orchards.
1b. Approach (from AD-416):
Determine critical parameters (i.e. photoperiod, chilling requirement) for diapause induction and completion in apple maggot from Washington State. We will include obligate diapausing, cafultative diapausing, and putative non-diapausing portions of AM populations. Determine critical parameters for growth and development of apple maggot and Western cherry fruit fly under climatic conditions specific for tropical regions.
3. Progress Report:
The work summarized in this Progress Report relates to objective 5 in the Project Plan for 001-00D: 5. Develop systems approaches involving combinations of various methods and technologies, both for management of codling moth in suburban and agricultural settings, and to reduce the probability of insects infesting fruit that is packed and shipped domestically and internationally. The current goal of the project is to develop information on the effects of various environmental factors on the survival and emergence of apple maggot in order to develop accurate ecological niche models to predict the potential of this pest to establish and spread in countries importing apples from the U.S. These models can be used to maintain and create new export markets for U.S. apples. To achieve this goal we addressed the following technical objectives: 1) Determine critical parameters (i.e. photoperiod, chilling requirement) for diapause induction and completion in apple maggot from Washington State. 2) Determine critical parameters for growth and development of apple maggot and Western cherry fruit fly under climatic conditions specific for tropical regions. During this past year we collected over 20,000 apple maggot pupae from field infested fruits from Western Washington State. These pupae were used in experiments to examine the impact of temperature, humidity, and day length on fly emergence. These data are critical to develop accurate ecological niche models to determine the potential of this pest to establish and spread in countries importing U.S. apples. We conducted studies on metabolic heat rates and respiration of apple maggot pupae following cold storage and exposure to various day length and temperature conditions using differential scanning calorimetry and oxygen uptake monitoring. We also determined the lipid and carbohydrate levels of these pupae. We determined apple maggot cold hardiness using the differential scanning calorimeter. We determined that pupae take approximately 10 days to fully develop cold hardiness by suppressing their whole body supercooling points through the removal of gut contents, increases in lipid content, and binding free water. These data provide critical information on the physiological mechanisms of diapausing apple maggots and their potential to establish and spread in countries where they are not currently known to exist. The results of the metabolic, cold hardiness and emergence patterns under various day lengths and temperature conditions were used to develop a model to predict apple maggot potential to spread in other countries importing U.S. apples. These models will be used to maintain and expand exports of apples where apple maggot is a pest of quarantine concern, but is predicted to be unable to establish a population.