New entomology professor’s studies enlighten means for better biological control

Marianna Szűcs’ research published in "Proceedings of the National Academy of Science" provides insight into improving establishment success of biological control agents.

Marianna Szűcs

Marianna Szűcs, a new assistant professor of entomology, is arriving on campus ready to build off her work published recently in the “Proceedings of the National Academy of Science.” Szűcs is a co-first author for the studies that occurred in Ruth Hufbauer’s lab at Colorado State University.

Biologists are increasingly recognizing that evolutionary change can occur in much shorter time scales than previously thought. In fact, changes may be fast enough to be observed in real time, affecting ecological processes, such as population dispersal or demography. These ideas are so new that there is little experimental evidence to back them up.

Szűcs and Hufbauer’s team explored whether evolutionary change could occur within a few generations when a species arrives in a new habitat and how it might influence population size and range expansion. They used a model beetle system, red flour beetles (Tribolium castaneum), to test their theories about colonizing populations. Red flour beetles can complete a generation within just five weeks, making it possible to follow them over multiple generations as they adapt and spread in a new environment. To measure the strength of rapid evolution, the researchers compared populations that were allowed to adapt and spread unconstrained to populations where they prevented evolution.

Within six generations, populations allowed to evolve grew three times larger and spread 46 percent faster than non-evolving populations. Evidently, rapid evolution drives both increases in population size and expansion speed from the outset, acting as an architect of successful colonization and range expansion. These results imply that adaptation and other rapid evolutionary processes are likely critical in determining how large the colonizing population becomes and how widely it expands in its new environment. These can be unintentionally introduced invasive species or intentionally released biological control agents or endangered species being relocated or reintroduced into new habitats.

Szűcs said, “For those of us working with biological control, these findings mean in working with planned releases we should promote genetic and demographic processes that increase evolutionary potential while trying to prevent these in invasive species.”

Szűcs says her research program at MSU will build on findings from this and other similar laboratory experiments from her postdoctoral work that tested basic ecological and evolutionary mechanisms operating during colonization. Even though biological control agents are released intentionally, their establishment rates are still relatively low. It may be possible to improve establishment by promoting processes that increase evolutionary potential.

For example, making fewer releases with more individuals in each release might increase establishment success and persistence by reducing genetic drift and inbreeding that occur in smaller populations. Larger population releases may also buffer against the demographic cost of selection, providing more time for adaptation to occur. It might be possible to expedite adaptation by ensuring sufficient genetic variation in founders or by enabling hybridization between genetically distinct populations of biological control agents to increase their genetic diversity.

“At MSU, I look forward to testing these hypotheses in the field,” Szűcs said. “I would like to design ongoing and new biological control releases in an explicitly experimental way to better understand the mechanisms that impact establishment, population growth and range expansion of agents, which I hope will ultimately improve success rates and effectiveness of biological control.”

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