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BEN # 49

Adolf Ceska aceska at CUE.BC.CA
Wed Feb 10 10:01:00 EST 1993

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No. 49                            February 10, 1993

Address: aceska at cue.bc.ca         Victoria, B.C.


Feb 12, 1993, "Grasslands and Oak Woodlands of the Pacific
   Northwest" slide presentation by Reid Schuller.
   Newcombe Theatre, 7:30 p.m., tickets $3/$2.
   Reid Schuller is a plant ecologist studying native plant
   communities and is currently involved as a natural area
   scientist, in Washington state, monitoring the restoration of
   grasslands and oak woodlands.
Feb 18, 1993, "Costa Rica and Resplendent Quetzal" - world
   premiere of a video by Adolf and Oluna Ceska. Newcombe
   Theatre, noon hour (12:15 to 1:15 p.m.), admission free.
Feb 19, 1993, "GARRY OAK MEADOW COLLOQUIUM" - University of
   Victoria, Elliot Building # 167, 8:30 a.m. - 5:00 p.m.
   Speakers will address Garry Oak vegetation, its origins,
   history, rare species, insects, vegetation management, community
   planning, and discuss the role of municipal governments and
   Organized by Biology Department, UVIC with the help from the
   Garry Oak Meadow Preservation Society. For more information
   call Richard Ring (604-721-7102), Richard Hebda (387-5493),
   or Joyce Lee (386-3785).

From: Chuck Goelzer Lyons <cgl1 at cornell.edu> [from ENTOMOL-L]

A tiny caterpillar may be responsible for doing what herbicides
and harvesters could not--controlling one of the worst aquatic
weeds in the United States, Cornell University biologists say.

The leaf-eating larvae of an aquatic moth may be the cause of
dramatic declines observed in the weed, called Eurasian
watermilfoil (Myriophyllum spicatum), in Ithaca's Cayuga Lake.
If so, the moth could be a biological control agent, replacing
or supplementing millions of dollars spent annually in the U.S.
for artificial control. But more tests are needed to make that

"In the early 1970s, Eurasian watermilfoil made up 90 to 99
percent of the plant biomass in Cayuga Lake," said Robert L.
Johnson, a Cornell ecology researcher. "The plants were growing
from 3 to 20 feet long--and as long as 35 feet--starting from
the lake bottom and reaching for light, forming dense canopies
at the surface."

Beginning in 1986, Johnson's annual surveys of Cayuga Lake
aquatic plants found a steady decline in Eurasian watermilfoil.
By 1992, the nuisance plant had diminished to 10 percent of its
biomass in the 1970s. Searching for causes, he looked for the
moth, Acentria niveus, which Middlebury College biologists
previously reported in milfoil plants of Lake George, between
Vermont and New York State. The insect, also an exotic
(non-native) species, was identified near Montreal as early as
1927 and has since been collected in Massachusetts and on the
Canadian and U.S. sides of the Great Lakes.

The Cornell biologist found hundreds of insect larvae--each
about the size, shape and color of a grain of rice--eating the
tips of Cayuga Lake's milfoil in the summer of 1992. The tiny
caterpillars use their silken thread to bind milfoil's feathery
leaves into individual nests called larval retreats, effectively
halting growth of the plant stems.

When the caterpillars are not consuming leaves that hold their
retreats, they dine out on other plant parts, Johnson said. The
larvae are believed to spend up to 10 months of their lives
under water, before emerging as adults. Male moths fly for a few
days, then mate at the water's surface with females. Female
aquatic moths submerge to lay eggs on underwater plants, and the
cycle begins again.

Cornell entomologists John G. Franclemont and E. Richard Hoebeke
identified the Cayuga Lake moths as the same species or a close
relative to the ones found in Lake George.

Just because aquatic moths thrive where Eurasian watermilfoil
declines does not mean a successful biological control for the
weed has been found, cautioned Nelson G. Hairston Jr., a Cornell
professor of ecology and systematics. Controlled experiments
could determine whether other factors are involved, he said. For
example, some disease may be affecting the plants' health,
making them more vulnerable to insect predation. Or water
turbidity (cloudiness) from algal blooms in the early season
(when milfoil plants try to reach for the surface) may retard
their growth, he said.

At Cornell's experimental ponds, where controlled studies of
aquatic weeds and other plants and animals are planned for 1993,
biologist Johnson is not ready to ship moths to every lake with
a Eurasian watermilfoil problem. But their presence, he said,
complicates strategic planning for aquatic weed control.
Weed-harvesting machines, which cut the tops of aquatic plants
in some lakes, also may remove beneficial insects.

The harvesting machines' effectiveness already is in doubt from
Cornell studies that found weed-cutting may actually encourage
weed growth, Johnson said. Stray pieces of aquatic weeds from
the harvesters take root on lake bottoms, the same way gardeners
produce new plants from cuttings.

Further, the weed cutting only temporarily opens lanes for
boating and swimming, Johnson's measurement of plant growth has
shown. Like a fresh-mown (and well-watered) lawn, the Eurasian
watermilfoil soon rebounds even stronger than before.

From: C.J.O'Kelly <COKelly at massey.ac.nz> [from USENET]

Dammit be careful out there!!!

Some years ago, the Botany Division of New Zealand's Division of
Scientific and Industrial Research (DSIR) came to a similar
conclusion, that the day of free taxonomic IDs was at an end. 
Hence they began charging.

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