Insect pests cause billions of dollars of damage to crop plants world-wide each year. With the continuing globalization of agriculture, crops are routinely introduced into new locations where they will come into contact with novel insect pests, and insect pests are frequently inadvertently introduced to new areas where they come into contact with novel crops. Therefore, a critical question is what are the factors that facilitate or prevent insects from becoming established on a novel plant? The apple maggot fly, Rhagoletis pomonella, is a model system for understanding how plant-feeding insects can move onto new hosts. These maggots are native to North America and historically fed on the fruits of hawthorn trees. However, after domesticated apples were introduced into the northeastern United States approximately 350 years ago by English and Dutch settlers, R. pomonella began feeding on apple fruits and has become a significant pest of domesticated apples. In areas where apples and hawthorns occur together, the two plants produce fruit at different times during the summer. The adult flies, which lay their eggs on the fruit, are short lived. This has lead to a separation in the timing of occurrence of the apple and hawthorn flies, which was critical for R. pomonella to become a pest of apples. Much is known about the genetics of life history timing and the shift onto apples in this fly, but little is known about the physiological traits that have facilitated the shift. This project will investigate the physiology of life history timing and determine if three critical physiological traits, fat storage, metabolic rate, and body size, differ between the apple and hawthorn flies, and determine if they are linked to specific genetic markers that are associated with differences in life history timing. This work will provide the first synthesis of physiology, genetics, and life history timing in a plant-feeding insect and will serve as a foundation for understanding how physiology may affect life history timing and either facilitate or prevent novel interactions between insects and plants, a critical question for both evolutionary biology and agriculture.
The PIs have a strong record in educational outreach and training, including traditionally underrepresented groups. This project will include training of postdocs, graduate and undergraduate students. Linking climate related physiology to insect host race formation will provide important information for understanding host range change and future pest problems as a consequence of climate variation.
