Invasive Species & Biological Control

Invasive species are pervasive across almost all ecosystems and landscapes. And we spend billions of dollars every year trying to remove them or mitigate their impacts on agriculture, recreation, and ecosystem services. Biological control is one self-sustaining way to keep invasive species in check by using natural enemies of the invasive species. A natural enemy could be a predator or herbivore that attacks and eats an organism. Many natural enemies have evolved over millions of years to have very tight associations with their host, so they no longer are able to use any other organism as their host. These highly specialized and host-specific natural enemies (usually insects) that have tight associations with invasive species can be released where the invasive is a problem and help to control the invasive. 

I'm interested in using these applied systems to understand basic biological questions and improve conservation of native ecosystems.

Tamarix - Diorhabda Biocontrol

Much of my work has been on the "biocontrol" system of the invasive plant tamarisk and it's natural enemy, the tamarisk beetle.

Tamarisk (primarily Tamarix chinensis and Tamarix ramosissima) was introduced to the United States in the 1800s. Tamarisk is natively from Europe, Asia, and North Africa and it grows in riparian areas (around lakes, rivers, and streams). People in the US planted tamarisk because they thought it would help to stabilize streambanks, provide windbreaks, and shade. It did those things, but people didn't know it would spread out of control and also crowd out the native species that already grew in the riparian areas, like willows.

Tamarisk, an invasive plant in the western US

Because tamarisk is so widely distributed and grows back very fast, it is difficult to manually remove tamarisk. That's where biocontrol comes in: if we could find a natural enemy of tamarisk that could reduce how fast it grew, we could limit tamarisk's impacts and make it easier to remove manually. Scientists found the tamarisk beetle (Diorhabda carinulata) that had spent millions of years evolving alongside tamarisk in Eurasia, so it had become a specialist - it couldn't eat any crops or other important plants. So, in 2001 the tamarisk beetle was released onto tamarisk in the US. It was just released at a couple sites, but since about 2010, the beetle has been moving by itself to fresh patches of tamarisk and on its way, a lot of tamarisk has been eaten and died. This is paving the way for native plants to be restored to the area.

Tamarisk beetle, biocontrol agent for tamarisk

Other Diorhabda projects

Has the tamarisk beetle become better at flying during its range expansion?

How does the tamarisk beetle time winter dormancy after range expansion?

Could adaptation of winter dormancy impact dispersal evolution of the tamarisk beetle?

Are hybrids between multiple tamarisk beetle species less host specific?