Virus or Bacteria?

Virus or Bacteria?

City officials are debating the best way to fight gypsy moths.

Monticello Park is a quiet space of trees and shrubs set in the picturesque Beverley Hills neighborhood — the kind of place that could be easily overlooked by those who were not neighbors or bird enthusiasts. Every spring, area residents flock to the park to get a first-hand look at a wide variety of warblers, vireos, thrushes and other passerines. According to the Cornell Lab of Ornithology, it’s one of the top 10 birdwatching sites in the county.

“It’s quite a famous little park,” said D. Michael Fry, director of pesticides and birds for the American Bird Conservancy. “The top 10 designation says it all.”

But the visiting warblers might have a hard time finding food this year if the city decides to spay a bacterium called as “Bacillus thuringiensis,” commonly known as B.t.

Last month, the City Council was set to approve a plan for aerial spraying of 75 acres in the Beverley Hills neighborhood to prevent deforestation of one of the city’s lushest areas. But council members delayed the program when they found out about the catch — although B.t. is safe for humans and highly effective, the bacteria kills caterpillars indiscriminately, doing away with the canker worms that are a major source of food for warblers. When several bird enthusiasts asked the City Council to examine alternative methods, they voted to defer the matter until the council’s Feb. 13 meeting.

“It’s a matter of rolling the dice in some respects,” Fry told City Council members during the public hearing. “It will cut down on the food supply of certain populations of birds.”

CITY OFFICIALS are examining an alternative way to target the gypsy moth caterpillars that would not disturb the canker worms. Arborist Jerry Dieruf, who works for the Alexandria Department of Parks and Recreation, said that he is investigating the possible use of a virus product manufactured by the United States Forest Service called “Gypchek” — an organism made from the “nucleopolyhedrosis virus.”

“We don’t have all the information yet,” said Dieruf, who is collecting information to present it to City Council members later this month. “At this point, we’re not even sure if the Gypchek will even be available.”

Because supplies of the virus are limited, the Forest Service gives preference to areas that are populated with endangered species. Alexandria has no such species, so the city government would have to wait until supplies are available — a situation that could cause a problem as the spring approaches. Because of the gypsy-moth life cycle, whatever eradication program the city decides to use must be ready in the first week of May.

“The research I’ve seen said that nine trees have seven or more egg masses,” said Fry. “So it doesn’t look to me like there is going to be a big problem this year.”

Nevertheless, city leaders say that they are committed to engaging in some sort of program to prevent deforestation — and they want to get the most bang for their buck. Dieruf said that although using the virus wouldn’t harm the canker worms, it has a kill ration of 60 percent to 80 percent. B.t., on the other hand, has a kill ratio of 80 percent to 90 percent.

“The Department of Parks and Recreation believes very strongly that B.t. is the way to go,” said Brian Hannigan, a spokesman for the city government. “The other means won’t have the same efficacy.”