2007 Science, Technology and Environment

Raymond Carruthers and Jack DeLoach

Developed environmentally friendly biological controls for saltcedar, an invasive tree that inflicted billions of dollars of damage to agricultural and natural areas.

Aliens are stealing over $130 billion of consumer and taxpayer money all across the United States, each and every year. Don’t worry. There’s no need to call the Men in Black. These aliens are plants and animals that come from other countries and then setup shop here in America. One of the worst of these invaders is saltcedar, a shrub to small tree that has overgrown many western waterways and lakeshores. At one point, the saltcedar had spread to 14 states, covering 2 million acres and inflicting $2 billion annually in economic damage. For these aliens, you needed to call Dr. Ray Carruthers and Dr. Jack DeLoach of the USDA Agricultural Research Service (ARS).

In the case of saltcedar, Drs. Carruthers and DeLoach eventually got the call, and after years of systematic evaluation, they developed a simple low cost solution to this problem – a beneficial insect that is able to combat this “invasive species” all across the country. This was no simple task, as it required hunting down the origin of saltcedar and assessing nature’s means of keeping it in balance. In six arduous sojourns, they followed saltcedar to its origin and, together with local cooperating scientists, identified more than 300 saltcedar-feeding insects from North Africa to the Mediterranean Basin to the Middle East to China. Together, they selected a single type of leaf beetle that strips the foliage from saltcedar and ignores all other plants. In USDA terminology this is called biological control, a technique that is extremely environmentally friendly when compared to applying harsh chemical pesticides.

The process of importing, testing and obtaining clearance for release of this beetle in the United States required years of ecological research and coordination with many different state and federal agencies. Detailed assessments of the needs of many stakeholders, from farmers to environmental groups were also taken into consideration. Many people believed that a consensus solution would be impossible, but Drs. DeLoach and Carruthers were able to pull it off. The pair organized the Saltcedar Biological Control Consortium, a group of more than 60 federal, state, environmental, agricultural and private groups working together to provide expertise, advice and project coordination across multiple states. Their technology is now being used in action programs covering private/ federal lands and even in protected areas such as Big Bend National Park.

These saltcedar leaf beetles reproduce at self-sustaining rates, spread naturally across the environment to other saltcedars, so the cost is low and the solution is widely available to all. The beetles only attack saltcedar, so they do not disrupt the balance of the natural environment or damage valuable crop plants. Also, after initial testing and implementation, adaptations continue to be made by the team to find the most effective solution for all affected areas from Mexico to Montana and from California to the Mississippi River. Currently, tens of thousands of acres of saltcedar have been treated and many more areas are now being targeted.

Because of the work of Drs. Carruthers and DeLoach, native plants are expected to reestablish themselves in areas once devastated by saltcedar. Municipalities and farmers can expect increased water for city use and irrigation. Wildlife, including several endangered species, is expected to recover. Control of the saltcedar is also expected to reduce wildfires, allow gradual soil recovery in currently infested areas and increase recreational usage of the affected lands. The saltcedar was one heck of a land management problem, but DeLoach and Carruthers came up with an even more impressive and sustainable solution – beneficial insects.

The team’s innovation goes further still, as Drs. Carruthers and DeLoach work together on new partnerships with NASA and other agencies to use satellite technology and computer models to assess invasive species and create images that can be used to track the spread and impact of pests and the biological control agents that can be used to manage them. Although saltcedar has been their bread and butter for the past several years, both scientists have applied their expertise to many other invasive species problems and have helped to resolve a wide range of other similar issues including invasive insects like gypsy moths, grasshoppers, and whiteflies and a number of invasive plants including noxious aquatic weeds such as water hyacinth and alligator weed. Look out invaders. USDA-ARS scientists are fighting back.