Many insects, including pest species that harm crops and transmit disease, depend on symbiotic bacteria for survival. This community of symbiotic bacteria, known as the microbiome, lives inside their host's cells and tissues and is passed directly from mother to offspring. These bacteria often benefit their hosts, for example, by producing required nutrients missing from the diet. But symbionts also can undergo genetic changes detrimental to hosts. This project addresses whether and how detrimental evolution of symbionts affects their host insects. The focus here is on one such group, aphids, which attack most of our agricultural crops and require symbiotic bacteria in order to grow and reproduce. The research will be used as a basis for teaching basic biology and genetics to University of Texas undergraduate students, including participants in a large freshman research program. Also, the results will further understanding of a significant group of agricultural pests, potentially contributing to the development of new methods of crop protection.
The experiments address how genetic variation of pea aphids affects their ability to regulate symbiotic bacteria and how genetic variation of the symbiotic bacteria affects their own multiplication within aphid hosts. The researchers measure how variation in symbiont regulation affects aphid growth and reproduction. Experimental genetic crosses of aphids that vary in levels of symbiotic bacteria will be combined with modern DNA sequencing methods to identify the parts of the aphid genome that affect symbiont numbers. In addition, symbiont strains will be transferred between aphid hosts using microinjection, to determine how different symbiont strains affect hosts.
