The red flour beetle is a widespread pest. Understanding how it can adapt to infest new products is economically important and addresses general questions about adaptation and diversification. In initial dissertation work, the Co-PI found that flour beetles adapt to soy flour within eleven generations and hybridization between beetle populations increases adaptation. While increased adaptation in hybrids can be caused by recombination of parental genomes (the standard explanation), increased performance might also be caused by recombination of symbiotic bacteria from parental populations. This proposition will be tested by comparing symbiotic bacteria of soy-adapted and wheat-adapted beetles. Bacteria will be identified by high-throughput DNA technology. Antibiotics will be used to remove symbiotic bacteria to determine whether bacteria are responsible for differences in performance.
This project will produce data relevant to agriculture, conservation, and education. Results will be invaluable to policy makers in the growing organic agriculture industry when making decisions about storage of imported food products when fumigation is not an option. Similarly, results will be of service to conservation organizations interested in preventing invasions by exotic species or facilitating reintroduction of endangered species to altered environments. The PI and Co-PI mentor undergraduate students by involving them in data collection and analysis, and this funding will support development of a beetle module in the VolsTeach program at the University of Tennessee.
Intellectual Merit This dissertation improvement grant follows up on completed work showing that hybridization (interbreeding) between distinct lineages of flour beetles increased the rate of adaptation when beetle populations were introduced into a challenging new environment (soy flour instead of their normal habitat of whole wheat flour). We interpreted those results as the benefits of genetic mixing. The question addressed here is whether some of the variation in performance can actually be explained by the mixture of gut bacteria instead of beetle genes. We do not yet have a definitive result, but we have made several interesting discoveries and preliminary obserations. First, the particular bacteria we have identified (based on DNA analysis) will be of interest to specialists, including those working on strategies for flour beetle control (these beetles are important pests of stored grains worldwide). Second, moving beetles onto soy elicits rapid changes in their gut bacteria. Sometimes these changes mirror changes that occur normally in wheat flour when beetle larvae metamorphose into adults. In other cases, the bacterial assemblage in beetles living in soy are completely novel. We are still running statiscal analyses and some followup experiments to determine whether the assembly of these novel bacterial communities depends on mixing between beetles from distinct genetic lineages, and whether particular bacterial groupings are associated with ecological success of beetles on soy flour. Broader Impacts We proposed three kinds of broader impacts. First we trained many undergraduates (of various cultural backgrounds) in an independent study format to provide hands-on experience in academic research. Several have gone on to PhD and medical programs. Second, we developed a general biology lab curriculum emphasizing student-led research on flour beetles as model organisms. This has been implemented in honors biology and the VolsTeach program at UT. Finally, we hope ultimately to provide recommendations for the stored products industry regarding the evolutionary risks of pest admixture.
