Play a Beetles Song, Protect a Tree

February 15, 2010

TEXAS GAVE US Buddy Holly and the Crickets; Liverpool, England, the Beatles. Far from competing in the musical arena with the Crickets or challenging Liverpool’s Fab Four, forestry entomologists across the border from Texas in neighboring Louisiana (as well as in Arizona) are tuning into wild Beetle chirping songs to learn how to broadcast a sound, nontoxic form of pine forest bark beetle control.

The Beetles are an unusual group in the animal world. Known to entomologists as the insect order Coleoptera, “Beetles make up 40% of all insects and there are eight times as many beetle species as there are fish, amphibian, reptile, bird and mammal species put together.” The beetle-friendly, Australian Museum web site in Sydney also says: “There are over 350,000 different known beetle species worldwide and new species are being discovered all the time.” More likely the total number of known and unknown beetle species is in the millions; no one, not even Wikipedia, knows for sure.

Beetle lovers, besides having many new species still available to discover and describe, are finding gainful employment keeping up with the more pestiferous species. From downtown Chicago to New York City’s Central Park, Asian longhorn beetles have been famously chomping away at urban forests. In Michigan alone, the emerald ash borer has felled 50 million ash trees in recent years. And this is only scratching the surface of what is out there, and has spread worldwide via wooden shipping pallets, tourists, trains, planes and ships.

Though most beetle species are benign or beneficial, the fight against the more pestiferous species generates a range of interesting research presentations at Entomological Society of America (ESA) meetings. For example, just northeast of Los Angeles in the southern California county of San Bernadino, USDA Forest Service researchers such as Andreana Cipollone are testing SOLARIZATION to stop firewood transport from spreading goldspotted oak borer (Agrilus coxalis), a pesky beetle infesting 50% of oak trees and killing over 22,000 oaks in the infestation zone. Solarization involves covering firewood cords or piles with aluminum mesh screening or plastic tarps to solar-cook the wood and kill or stop beetle emergence.

In the southeastern United States, the southern pine beetle (Dendroctonus frontalis) is the most economically damaging pine pest, causing over $2.5 billion in damage in the last decade. Large numbers of this aggressive bark beetle gang up on and overcome the defenses of healthy trees. Female beetles attract male beetles with sex pheromones; arriving males stridulate (rub together body parts) to produce a double-duty chirping song that wards off rival males and attracts females. Females produce their own chirping song to keep other females at a distance, which gives the offspring more room to develop inside the tree galleries.

“We intend to explore the possibility that song playback devices may find utility in manipulating southern pine beetle behavior at the scale of single trees, and thereby might offer a non-chemical means of tree protection,” reported Christof Stumpf of Louisiana State University at the December 2009 ESA annual meeting in Indianapolis. At the same ESA meeting, Richard Hofstetter of Northern Arizona University in Flagstaff noted that Arizona bark beetles can also be defeated with their own songs. But according to Arizona Republic reporter Shaun McKinnon (Feb. 09, 2010) and Discovery News reporter Jennifer Viegas (Feb. 10) the Arizona bark beetles were not deterred by Heavy Metal rock music or Rush Limbaugh radio broadcasts played backwards or forwards.

Evidently, we must tune into the sounds of nature itself and not rely on either political commentators or rock musicians to solve our pest problems for us.


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