Examining Genetic Population Structure in the Invasive Aphid Pest Hyalopterus pruni and its Parasitoid Aphidius transcaspicus: Implications for Improving Biological ControlEPA Grant Number: FP916380
Title: Examining Genetic Population Structure in the Invasive Aphid Pest Hyalopterus pruni and its Parasitoid Aphidius transcaspicus: Implications for Improving Biological Control
Investigators: Lozier, Jeffrey D.
Institution: University of California - Berkeley
EPA Project Officer: Jones, Brandon
Project Period: January 1, 2004 through December 31, 2004
Project Amount: $105,848
RFA: STAR Graduate Fellowships (2004) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Biology/Life Sciences , Fellowship - Entomology
Invasions of exotic insect species represent one of the most substantial threats to agriculture in the United States, causing an estimated $14.4 billion in damage to crop systems annually. Classical biological control, the purposeful introduction of natural enemies from a pest’s region of origin, is one of the most desirable means to mediate the effects of invasive pests without the use of chemical pesticides. Unfortunately, the impact of biological control has been limited because of its relatively low success rate. Biological control introductions might be improved, however, by addressing fundamental concerns, such as the proper identification of pests and natural enemies; determining the geographic source and invasion history of the exotic pest and its potential for range expansion or host shifts in the invaded region; and isolating the most virulent natural enemy strain(s) for biocontrol introduction. The objective of this research project is to examine these issues in a model biological control system: the mealy plum aphid (Hyalopterus pruni), an invader from the Mediterranean that currently threatens prune production in California, and its parasitoid (Aphidius transcaspicus).
Insect species are structured typically into a mosaic of genetically and ecologically distinct populations, each with unique ecological roles, associations, and selection pressures. An understanding of population structure for an invasive pest in its ancestral range can be used to trace its origin and thus predict many important biological properties of the pest in the invaded region, as well as to choose the best possible enemy source for biocontrol introduction. This project uses a combination of molecular tools and ecological assays to examine population structure in H. pruni and A. transcaspicus. Mitochondrial COI and nuclear gene sequences will be used to reveal deep level structuring, such as the presence of cryptic species or biological races, and to clarify unresolved taxonomic questions in these groups. I also am developing an array of microsatellite markers to examine finer scale population level processes and to assign invasive H. pruni ’s genetic origin in the Mediterranean. This genetic data then will be used as a foundation for examining the relationship between population structure and variation in the strength of host-parasitoid interactions to help discover the most compatible Aphidius strain for biological control introduction against H. pruni . For these experiments, I will expose individuals from various Mediterranean parasitoid populations to H. pruni populations collected throughout California and will measure various aspects of parasitoid reproductive success and virulence for each Aphidius strain. The resulting virulence measurements will be analyzed in combination with genetic data to ascertain the importance of population structure for predicting the outcome of reconstructed host-parasitoid interactions for the purposes of biological control. This research project will result ideally in the successful biological control of the mealy aphid in California, while also providing a methodology for improved biological control exploration in other systems.