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):
A. Collect existing data on basic biology of apple maggot in the Eastern U.S. and Mexico versus Pacific Northwest including obligate diapausing, facultative diapausing, and non-diapausing portions of the population. Collect existing data on WCFF in the Pacific Northwest. Data will include host range, distribution maps, climatic data, growth optima, upper and lower thermal limits, degree day models, diapause induction, maintenance, and completion. B. Enter existing data on AM and WCFF biology as well as environmental data of importing countries into risk modeling programs. Determine baseline for risk, and identify research gaps. C. Determine critical parameters (i.e. photoperiod, chilling requirement) for diapause induction and completion in apple maggot from Washington State. We will include obligate diapausing, facultative diapausing, and putative non-diapausing portions of AM populations. D. Determine critical parameters for growth and development of apple maggot and Western cherry fruit fly under climatic conditions specific for tropical regions. E. Identify improved attractants, such as fruit volatiles, for apple maggot fly in the Western U.S. Improved attractants will improve the accuracy of the data used for pest distribution, numbers (load factor), and help in establishing and maintaining quarantine areas. In addition, improved trapping methodologies will increase confidence in pest control measures with our trading partners. F. Demonstrate that morphometric and molecular methods can reliably separate the apple maggot and snowberry maggot. Misidentification of a non-quarantine pest as a quarantine pest can adversely affect trade and negatively impact risk assessment models. G. Hold a regional workshop on Western cherry fruit fly. The specific topic to be addressed is how to develop a model that can be used to predict the probability of an orchard being infested with cherry fruit fly.
3. Progress Report:
An extensive search for existing occurrence data for the three target species- collected data from Global Biodiversity Information Facility, National Agricultural Pest Information System, published papers and reports, published maps in books, and organized surveys was made and entered into informational databases. Climatic data layers in Geographical Informational System for the United States, Indonesia, Thailand, and Taiwan (19 bioclimatic data layers at 1-km and 5-km spatial resolutions) were successfully collected and processed into informational databases. Additional information on Aridity, monthly Potential Evapotranspiration, and monthly Solar Radiation data layers (a total of 25 layers) were added to the databases. The Geographical Informational System layers were used to develop initial ecological niche models for apple maggot, western cherry fruit fly and codling moth. As the models were being developed, researchers identified deficiencies in the data that need to be developed to improve the accuracy of the models. These include determination of upper and lower thermal limits for apple maggot and western cherry fruit fly. Fruit volatile blends derived from apple, black hawthorn, ornamental hawthorn, and snowberry fruit were isolated and identified in the laboratory and tested in a flight tunnel, which confirmed the attraction of flies to them. The blends were tested with traps deployed in the field in western Washington. Flies in apple trees were most attracted to the apple blend, whereas flies in ornamental hawthorn trees were most attracted to the ornamental hawthorn blend. Flies in both host trees were not or were not highly attracted to a control or to black hawthorn and snowberry blends. The wings of more than 200 apple maggot and snowberry maggot flies and their hybrids have been mounted on slides. Multiple body measurements of all these flies have also been taken. Wings have been photographed and the images have been entered into a software program (morphomorics) for digitizing landmarks on the wings. Use of microsatellites detected potential diagnostic differences in the genomes of apple and snowberry maggot flies. Western cherry fruit fly and apple maggot pupae collected from field infested fruits were used to determine the impact of temperature and day length on fly emergence. The work reported here addresses objectives 1 and 5 of the parent project plan.