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Posts Tagged ‘Boulder Colorado’

Doing battle with a bug threatening to destroy thousands of our trees takes patience, strategy and a variety of tools. You can throw thousands of staff hours at it. You can remove hundreds of infested trees. You can even sizzle the invaders with electrified, bug-zapping replicas of the female emerald ash borer (though effective on a testing scale, I can’t envision stringing thousands of lines of the shocking beauties throughout the trees).

But sometimes what you need is an answer both subdued and eloquent, another bug to target a thug that’s attacking our ash. Dubbed the “Green Menace,” the emerald ash borer (EAB) has been found in Boulder, and Colorado’s interagency EAB Response Team is pulling out all the stops to try and halt the spread of the insect.

With that in mind, they’re releasing wasps, but not the kind that disrupt picnics or carry toddlers off for a midnight snack. These tiny insects are harmless to humans and beasts; they’re stingless and don’t concern themselves with picnics or soda pop.

Instead, Tetrastichus planipennisi target EAB larvae as they grow under the bark of the tree, laying eggs inside their bodies for the hatching wasps to use as hosts. The growing parasitoid larvae ultimately kill their EAB hosts before they can mature. Each female wasp can lay up to 100 eggs in a single larva. 

Tetrastichus planipennisi  pupae

Tetrastichus planipennisi pupae

 More than two thousand of the wasps have been brought to Boulder already, and released through the combined efforts of the Colorado Department of Agriculture, University of Colorado, City of Boulder and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS). For years, USDA has been employing biocontrols for use against EAB in the U.S., and they are providing the wasps at no charge to Colorado.

There are moments during which I suddenly have soundtrack music cue up in my head, and in this case, the snippets of the William Tell Overture distract me as I contemplate what the wasps will do. But the release itself is a tad anticlimactic: no one screams “Release the wasps!” while swarms of adults cloud the skies. Rather, the release is a quiet one; the wasps rest in their pupal stage, nestled together in wood bolts attached to trees. They’ll gradually chew their way out and fly to find their prey, quietly doing what many of us cannot: finding EAB larvae.  Climbing

It is hoped that the wasps will help suppress EAB populations in the city and manage the insect’s potential future spread, much like a hero arriving to save the day. The wasps have been released on the East Campus of the University of Colorado, in a location that offers the wasps rich hunting, as ash in this area are hard-hit by the bug.

According to a press release from the EAB Response Team, up to two additional Tetrastichus releases are planned in Boulder in the coming weeks, dependent on weather conditions. The parasitoid wasp Oobius agrili, which targets Emerald Ash Borer eggs laid in the late spring or summer, also is being considered for release here in 2015.

Like EAB, Tetrastichus is native to Asia and the USDA conducted extensive research on it in its native range before bringing it to the U.S. for testing. Once here, they conducted further testing to ensure that the wasps won’t attack other insects in the absence of EAB. They determined that the wasp prefers to hunt EAB above all else, and even if they lay eggs on non-EAB larvae, the eggs don’t survive. Due to this, the USDA determined that Tetrastichus poses little risk to other insects here.

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Watching the 7,000-acre fire burning west of Boulder reminds me that every area has its share of heartbreaking natural disasters.  We live in a dry state where fire is a destructive force we fear every year.   Seen from my home to the east, the plume of smoke from the Four Mile fire is boiling near the flames as it rises to spread across the sky.

Passing overhead, a fine ash settles down, coating my home and land.  The question callers are asking is:  Will this ash harm the plants?

“This late in the season – September 7 – a lot of the trees and shrubs are starting to be ready to shed those leaves,” says Dr. Jim Klett, Professor of Horticulture at Colorado State University, “they’re prepared for winter and a little ash won’t harm them.  They’ve already set buds for next year.”

Showy fall color might be hurt by an ash coating, Klett said, by encrusting the leaves with gunk that diminishes the intensity of color.  But unless the ash is thick enough to smother the branches and buds, the plants will be fine.  Should that happen, a heavy rain will be enough to wash off the plants, or winds will move it off of the tree.

Of course, this advice is for those out of harm’s way.  Closer to the blaze, landscapes could get singed.  “If it’s near the fire and the ash is warm, yes, it can burn small holes in the leaves,” said Klett, but even then the leaves can take a bit of damage.

There’s little to be done except wait for the fire crews to contain the blaze, and hope for rain.

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