Landscape-scale treatment promising for slowing beetle spread

Feb 02, 2009

Mountain pine beetles devastating lodgepole pine stands across the West might best be kept in check with aerial application of flakes containing a natural substance used in herbal teas that the insects release to avoid overcrowding host trees, according to a team of scientists.

Findings from the U.S. Forest Service-funded study appear in the February issue of Forest Ecology and Management. The study was conducted in California and Idaho, and showed how applications of laminated flakes containing a substance called verbenone resulted in a three-fold reduction in insect attack rates, compared to areas where they were not applied.

The technique could provide a way to treat infestations on a large scale and limit further spread into millions of acres of trees made vulnerable because of climate change, overcrowding and fires.

It could also be an alternative to insecticides, which can have adverse environmental effects. Thinning of some overstocked forests is still recommended to reduce susceptibility to bark beetles. But, the flakes can provide some protection for the dense, old-growth stands required by wildlife, according to the scientists.

The largest beetle outbreak in North American history is now occurring in Canada, where more than 22 million acres are affected, according to the British Columbia Ministry of Forests and Range. Outbreaks of this magnitude exacerbate global warming by converting forests from carbon sinks to carbon sources.

Scientists have known for more than a decade that one of the safest strategies for deterring such infestations was through application of verbenone, which beetles release to inhibit aggregation by members of their own species, and the Food and Drug Administration has approved for use as a flavor ingredient. But, manual application of verbenone is difficult where infestations cover thousands of acres in remote, steep terrain.

"Verbenone flakes gave significant protection from mountain pine beetles when applied to low to moderate beetle populations," said Nancy Gillette, a Forest Service scientist at the Pacific Southwest Research Station and one of nine researchers involved in the study. "Higher beetle populations will probably require higher application rates."

Gillette and her colleagues speculated that flakes released from the air might better disperse and simulate natural beetle release than large, manually-applied verbenone packets so they used helicopters to release flakes.

They treated 10 plots at two sites, one near Mount Shasta in Northern California and another in Idaho's Bitterroot Mountains. The sites had similar tree densities and existing rates of infestations. Helicopters dropped flakes on half of the plots and left the others untreated, with application rates of about 9.7 flakes per square meter.

The treatments reduced the level of attack to about a third of that in untreated plots in both California and Idaho. Future studies will test a biodegradable formulation of the flakes.

More information: The study, "Aerially Applied Verbenone-Releasing Laminated Flakes Protect Pinus Contorta Stands From Attack by Dendroctonus Ponderosae in California and Idaho" can be seen in the journal Forest Ecology and Management at: dx.doi.org/10.1016/j.foreco.2008.12.017

Source: US Forest Service

Explore further: Study casts doubt on climate benefit of biofuels from corn residue

add to favorites email to friend print save as pdf

Related Stories

Android gains in US, basic phones almost extinct

7 hours ago

The Google Android platform grabbed the majority of mobile phones in the US market in early 2014, as consumers all but abandoned non-smartphone handsets, a survey showed Friday.

SpaceX launches supplies to space station (Update)

7 hours ago

The SpaceX company returned to orbit Friday, launching fresh supplies to the International Space Station after more than a month's delay and setting the stage for urgent spacewalking repairs.

Recommended for you

US delays decision on Keystone pipeline project

Apr 18, 2014

The United States announced Friday a fresh delay on a final decision regarding a controversial Canada to US oil pipeline, saying more time was needed to carry out a review.

New research on Earth's carbon budget

Apr 18, 2014

(Phys.org) —Results from a research project involving scientists from the Desert Research Institute have generated new findings surrounding some of the unknowns of changes in climate and the degree to which ...

User comments : 0

More news stories

China says massive area of its soil polluted

A huge area of China's soil covering more than twice the size of Spain is estimated to be polluted, the government said Thursday, announcing findings of a survey previously kept secret.

UN weather agency warns of 'El Nino' this year

The UN weather agency Tuesday warned there was a good chance of an "El Nino" climate phenomenon in the Pacific Ocean this year, bringing droughts and heavy rainfall to the rest of the world.

Growing app industry has developers racing to keep up

Smartphone application developers say they are challenged by the glut of apps as well as the need to update their software to keep up with evolving phone technology, making creative pricing strategies essential to finding ...

Making graphene in your kitchen

Graphene has been touted as a wonder material—the world's thinnest substance, but super-strong. Now scientists say it is so easy to make you could produce some in your kitchen.