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NC State doctoral student wins Friends of Southern IPM Award for work on urban heat islands

A doctoral student at NC State University will receive a regional award in November for his work on urban tree integrated pest management.

NCSU Ph.D. student, Adam Dale, was one of several graduate students nominated to receive a Friends of Southern IPM Graduate Student award. The Southern IPM Center, which sponsors the award, gives one Masters award and one Ph.D. award based on the decision of an outside panel.

The bulk of Dale’s work has centered on tree health in urban heat islands, focusing on gloomy scale insect impacts on red maple street trees.

Adam Dale

Adam Dale

Urban habitats often create heat islands, regions of warmer temperatures as a result of less vegetation and more impervious surface cover like roads, parking lots, and buildings. Red maple trees are one of the most commonly planted trees in urban habitats because they grow quickly and are highly adaptable to a variety of soil and weather conditions.

Red maples are also one of the favorite feasts of the gloomy scale insect, a small insect that feeds on the tree’s nutrients by inserting a needle-like mouthpart into the bark. Gloomy scales have an armored covering as adults, so insecticides must be applied during the insect’s unprotected nymphal stage in May or June.

Dale’s first research project examined ecological interactions of the scale insects on street trees in their urban habitats. He tested two hypotheses: 1) that trees in areas where there was more vegetation would have fewer scale insects because of an abundance of natural enemies and 2) that the amount of vegetation would affect temperature, which directly affects the abundance of scale insects.

“My main prediction was that the less vegetation you have, the warmer it will be, so the pests are more abundant,” he says. “I was looking at how more vegetation leads to cooler temperatures and fewer pests and vice versa.”

He discovered that the number of natural enemies had no affect on the population of scale insects. Actually, temperature was the bigger factor in the plethora of scales on the trees. Trees at warmer sites had more scale insects, while trees at cooler sites had fewer insects.

That finding led to a second project: whether trees at warmer sites were more water stressed and in worse condition than trees at cooler sites.

Using a condition measuring scale that city administrations use to test tree condition, they rated several trees around different sites in Raleigh, North Carolina, and found that the trees with more scale insects at warmer temperatures were in worse condition than trees at cooler temperatures. In fact, hot sites had over twice as many trees in poor condition than they had in excellent condition. Cool sites were the opposite.

“We found that at hotter sites, there are more scales and trees are more drought stressed, which leads to worse condition,” he says.

Read more about the study in our March 9, 2014 blog post.

Dale and his advisor, Dr. Steven Frank, are using the data to create recommendations for city planners on where to plant trees.

Dale, who is from Greensboro, NC, started as an undergraduate at NCSU in general biology. He decided to begin graduate school in entomology after working during the summers with Dr. Frank on urban ecology projects. He decided that he wanted to concentrate on urban ecology and focus on urban tree health.

He will receive his award during an ornamental pest management symposium at the Entomological Society of America national meeting in November.

He is scheduled to graduate in December, but before that he wants to follow up on his findings from the temperature study.

“The big question to answer now is are all of these trees infested with gloomy scale and exhibiting canopy die-back, still providing adequate ecological services like photosynthesis?” Dale says. “Since cities are characterized by fewer trees, you want to maximize the benefits the trees are providing. We want to figure out how to minimize the impacts of the pests on the services offered by urban forests.”

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