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REF NO.: 350

SUBJECT: Student uses trees on Memorial University’s campus for elm spanworm research
DATE: June 28, 2005

Drivers passing by the St. John’s campus might wonder what the bags are all about. Trees near the R. Gushue Hall on the north side of the campus have seemingly sprouted a number of bags or pouches on the some of their branches. People of the capital city will be pleased to know that it’s spanworm research aimed at understanding more about the troublesome worm that has plagued the city’s trees in the last few years. The research is being done by master’s student and Memorial University alumna Heidi Fry. “My research is focused on why this outbreak has occurred in St. John’sand how the population will eventually collapse,” said Ms. Fry.

One of her experiments involves assessing the natural mortality of the different life stages of the elm spanworm - egg, larvae, pupae and adults. She is also assessing the effect that tree quality will have on decreasing the elm spanworm population. A part of her experiment is being carried out on six sycamore maples near the St. John’s campus residences.

“There are five pairs of sleeve cages on each tree - 10 cages in total on each tree,” she said. “For each pair of cages there is a control cage and a treatment cage.

“The control cage does not contain elm spanworm larvae, so there will be no defoliation within this cage. The treatment cage contains elm spanworm larvae so the part of the branch in this cage will be completely defoliated.

“Next year larvae will be put in both treatment and control cages to determine if the leaf quality has decreased because of the previous year’s feeding. This will be determined by assessing elm spanworm survival, sex ratio and reproductive capabilities. If quality is decreasing because of repeated defoliation then elm spanworm survival rate and reproductive capabilities may decrease and therefore the population size will start to decrease."

Ms. Fry graduated from Memorial with a B.Sc. (Hons.) in biology this past spring and is currently a candidate at the Universityof New Brunswickwith a co-supervisor at Canadian Forestry Services (Dr. Krista Ryall) in Corner Brook.

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