State response to browntail moth and to mosquitoes that are potential
vectors for West Nile Virus has residents polarized in coastal communities,
especially in areas where browntail moth is thriving this year and where WNV-
positive dead birds were discovered last fall.

Any talk of spraying for either creates concern about unintended effects
sprays might have on marine life, particularly lobsters.

Lobstermen have avidly opposed sprays of any nature — dimilin for browntail
moths, other insecticides or larvicides for mosquito control. Because of their
concern, lobstermen have helped scientists from the Maine Department of
Marine Resources (DMR) put out lobsters in cages near areas sprayed for
browntail moth. After aerial spraying of dimilin was completed, the lobsters were
returned to the DMR lab and observed until they molted.

Carl Wilson, scientist with DMR, says that people fear the sprays will
interfere with the lobsters’ molting. “Dimilin is a chitin inhibitor,” he explained,
“and could prevent lobsters from forming shells.” However, he says, so far,
laboratory monitoring of juvenile lobsters placed in spray areas has not shown
any discernible difference in the ability of these lobsters to grow new shells.

This year, eight lobstermen in Zone F helped Wilson and a professor from
Southern Maine Technical College place 125 lobsters around Casco Bay next to
towns where spraying was conducted: Freeport, Cumberland, Falmouth,
Yarmouth and Brunswick (Mere Point).

“We placed the lobsters in the areas where we expected the highest number
of passes by the spray plane,” Wilson says. In response to requests by the
Maine Lobstermen’s Association, this year’s experiments included both juvenile
and much smaller fourth stage lobsters so the latter can be observed through
several stages of molting.

Also, Wilson says, “there was a small army of fishermen and myself crawling
around at 5 a.m. setting up cards in advance of the planes coming to spray.”
These cards, placed next to spray areas, were specially treated to indicate if the
dimilin drifted out of the designated area into the 150-foot buffer zones
measured from high tide mark inland. So far, Wilson has observed that very few
cards showed indication of spray. “From what I saw, the pilot did a heck of a job,”
he says.

Richard Bradbury, the entomologist with the Maine Forest Service who has
coordinated the spray program, says it is at best limited because legally,
residents are allowed to opt out, and when they do, the fragmentation decreases
the effectiveness of the spraying program. “It’s been a difficult, frustrating issue,”
Bradbury admits. “We aren’t sure if we will do it again.”

Bradbury is encouraged by preliminary results of an alternative, experimental
program designed to eradicate browntail moth: spraying a baculovirus which
occurs naturally and attacks only browntail moth larvae. The virus, used
successfully in England to control browntail infestations, is not harmful to
humans or lobsters. Experiments are necessary, though, to determine if the
virus can be as effective in the Maine climate.

Dr. Jim Slavicek, a scientist with the U.S. Forest Service, applied the
baculovirus in two small areas of the Bowdoin College Coastal Studies Center
property in Harpswell. Bradbury says his initial observations show the virus is
working very well, with about 90 percent mortality of caterpillars two or three
weeks after the virus was applied. “So far, it looks good,” he says. “If it continues
to work well, we’ll test for another year and also see if we can produce the virus
on a larger scale.” He adds that it is possible scientists could encourage the virus
to spread on its own by introducing it into small sections, such as every tenth of a
mile, of a large area where the browntail is thriving.

Bradbury emphasized that it takes a lot of time to do research that can be
conducted only once each year when the caterpillars are present. “It’s likely
several years away before we can use the virus on a large scale,” he says, “but if
we can, it will provide tremendous benefits to people in the areas that have
browntail.”

Meanwhile, residents of Harpswell and other towns are putting up with huge
infestations of browntail, with caterpillars covering decks and yards. “It’s creepy,”
one Harpswell fisherman said. Weather conditions will determine the extent of
irritation residents experience from caterpillar hairs when the larvae sheds it’s
skin and hairs. “If it’s dry and those hairs are windborne, it’s the worst time for
folks,” Bradbury says. “With rain, the hairs get washed down to the ground. They
stay there and people are not exposed to them as much.”

West Nile Virus

In a recently issued Operational Plan for West Nile Virus in 2002, the state’s
West Nile Working Group, a 22-member multi-agency task force convened in
1999 to develop policy regarding WNV, reiterated its reluctance to use
adulticides or larvicides to control mosquitoes. Members recognize that unlike
other states in New England, spraying has never been a priority in Maine —
“Maine has never had a mosquito control program, as mosquitoes have
historically been viewed as part of our landscape,” the report states.

The group is spending the greater part of a $200,000 grant received from
Centers for Disease Control and Prevention (CDC) on educating citizens about
proactive measures they can take to control mosquitoes and prevent bites. It has
developed fact sheets on WNV that include information on personal protection,
mosquito control around the home, recommendations against utilizing pesticides
in yards and information on the dead bird surveillance system. These sheets
have been distributed to towns, campgrounds, youth camps, veterinarians, parks
and to agencies that serve senior citizens in the state.

The group is especially concerned about environmental damage if residents
purchase pesticides at the retail level and apply them haphazardly around the
home. Instead, the working group continues to urge residents to take precautions
to help prevent mosquito bites such as cleaning up mosquito breeding areas
around their homes, keeping grass and bushes well-trimmed, wearing long-
sleeved shirts and long pants when outdoors and applying insecticide to exposed
areas of skin. A complete list of recommendations is available at the Bureau of
Health’s web site, janus.state.me.us.

Since data in other states indicates that dead birds, particularly crows, are
the best preliminary indicator for the presence of WNV, the Working Group will
test dead birds for WNV again this summer. It asks citizens to report dead birds
to the toll free line, 888-697-5846. It also will continue mosquito surveys to
increase scientists’ understanding of the mosquito species present in Maine and
track the presence of those known to be WNV vectors, particularly in southern
Maine where seven WNV-positive birds were found last fall. Members of the
group’s Mosquito Surveillance Committee continue to gather information on the
use of larvicides and adulticides and how to monitor the environmental impact of
their use.

No human cases of West Nile Virus have been reported in Maine. In a 2002
WNV update, Roger Nasci of the CDC said that as of June 11, no human cases
had been reported this year in the U.S. A total of 41 crows and 18 other birds
with WNV infection had been reported in 2002 from 10 states, with
Massachusetts being the most northerly location.

If (more likely when, as it is known to overwinter) the virus shows up in Maine
this summer, the Working Group will handle each case individually. “Each
situation will be discussed by the Working Group, taking into consideration
variables like the time of the year; the population density, the population at risk
and locations of the events,” says the report.

Patrice Farrey, Executive Director of the Maine Lobstermen’s Association,
who has attended nearly all meetings of the West Nile Working Group, says of
the report, “Even though there could be the potential for spraying, I was very glad
to hear the WNV group come out and say they do not recommend spraying.”
She felt the group’s public education program has taken a big step forward over
last year, and recognizes that members of the group continue “to struggle to
understand the pesticide issue and its environmental implications.”