These moths aren't coddled

September 23, 2004, vol. 31, no. 2
By Diane Luckow

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Nothing spoils the satisfying crunch of a newly harvested apple faster than discovering a worm inside it, or worse still, half a worm.

Each year, codling moth larvae create havoc for apple and pear farmers.

In orchards not treated with pesticides, 85 per cent of the trees can become infested as the larvae eat their way out of the apple and then crawl into crevices in the tree trunk to spin their cocoons, pupate and repeat the cycle all over again.

Now, however, SFU PhD student Zaid Jumean has discovered a new, environmentally friendly way to decrease the population of codling moths.

He has identified the pheromone that the moth larvae use to attract each other to the same pupation site on the tree. Called an aggregation pheromone, it also attracts parasitoid wasps to the site, which then lay their eggs on the codling moth larvae. When the wasp eggs hatch, the wasp larvae eat the codling moth larvae. “These are moths that won't become adults and won't have a chance to produce new eggs,” says Jumean.

Together with SFU professor of bilogical science Gerhard Gries, Jumean has a provisional patent on the pheromone and is now testing a prototype trap with assistance from Pherotech, a company specializing in pheromone trapping.

So far, experiments show that the aggregation pheromone attracts 25 to 33 per cent more moths than traps without the pheromone.

Increasing trap catches of larvae in this way, in addition to the removal of larvae by the parasitoid and other control tactics, will help to further reduce codling moth populations.
Suppressing the moths' population density, says Jumean, should help to improve the health of the orchards.

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