Cutting Program Threatens Predators and Parasites of Brown Spruce Longhorn Beetles

Date: Thu, 3 Aug 2000 12:00:32 -0300 (ADT)
From: Christopher Majka <nextug@is.dal.ca>
To: Sustainable Maritimes <sust-mar@chebucto.ns.ca>
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Hi,

For those of you who may be interested, I enclose the following press
release by Friends of Point Pleasant Park.

Best wishes,

Christopher Majka

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PRESS RELEASE
Friends of Point Pleasant Park
Halifax, Nova Scotia
Contact: Christopher Majka (902) 425-3725

July 31, 2000	For Immediate Release

Cutting Program Threatens Predators and Parasites of Brown Spruce Longhorn
Beetles

Friends of Point Pleasant Park today are releasing the results of their
own independent investigations into predators and parasites of the Brown
Spruce Longhorn Beetle (BSLB) in Point Pleasant Park. 

"Contrary to early assertions that there were no predators of the BSLB,
Point Pleasant Park virtually teems with a constellation of predators and
parasites specifically known to prey on the Brown Spruce Longhorn Beetle
(Tetropium fuscum)," said spokesperson Christopher Majka. " Our
discussions with scientists here and abroad, our investigations of the
published literature, and most importantly, our observations in Point
Pleasant Park itself, confirm that there are already many well-documented
predators and parasites at work." 

In Europe the research by the Polish Institute of Forestry Research found
19 species of Ichneumon and Braconid Wasps which were predators of the
Brown Spruce Longhorn Beetle, with infestation rates as high as 70%. Both
of these groups of wasps are exceedingly abundant in Canada. 830 species
of Braconids have been recorded here and over 2,000 species of Ichneumon
Wasps are known in the country. Moreover both of these wasps are abundant
in Point Pleasant Park. 

"On many occasions I've observed at least three different species of these
wasps actually patrolling the surfaces of infected trees," says Majka, an
ecologist by training with a background in entomology and invertebrates.
"The wasps listen for the sound of larvae boring under the bark and then
inject an egg into the larval beetle. The young wasps then grow and kill
the larval beetles." 

One of the most authoritative reference on wood-boring beetles, Gorton
Linsley's book "The Cerambycidae of North America," also notes several
species of both of these wasps known to parasitize the wood-boring beetles
found in Point Pleasant Park. 

In addition to wasps, the Polish studies singled out woodpeckers
(particularly the Great Spotted Woodpecker), as significant predators of
BSLB. This woodpecker is very closely related to the Hairy and Downy
Woodpeckers, which are commonly found in Point Pleasant Park. Says Majka,
"On several occasions I've observed Downy Woodpeckers and Red Breasted
Nuthatches feeding very energetically on precisely the trees in the Park
that are threatened with cutting." 

An even more exciting recent discovery is that the Park is teeming with a
different kind of beetle, the so-called "Checkered Beetle," Thanasimus
dubius, both the adults and larvae of which are known to be voracious
predators of wood- boring beetles in general and of the genus Tetropium in
particular. "Recently in observing the beetles attracted to the bait logs
left by the CFIA in the Park I counted over 120 individuals of Thanasium
dubius - by far and away the most abundant beetle I could readily observe
in the Park," says Majka

Authoritative texts such as the "Manual of Common Beetles of Eastern North
America" note that: "The larvae live within the burrows of wood-borers or
under bark and are very useful in keeping these and bark beetles in
check," and that, "both larvae and adults are predators on bark beetles in
dead and dying spruce, pine and elm trees." Gorton Linsley's work
specifically indicates that the very closely related checkered beetle
Thanasimus trifasciatus is known specifically as a predator of Tetropium
beetles. 

"All of these studies and observations are a strong indication that the
predator and parasite set already known to be highly effective in
controlling wood-boring beetle numbers is alive and well and living in
Point Pleasant Park," says Majka. "In fact this is an indication that the
extremely low numbers of adult BSLB that the CFIA Task Force has been
finding are as a result of the population being kept in check by all these
insects and birds. The current cutting program is doubly tragic since in
addition to destroying any wood-boring beetles in the park (including the
three native species know to be there), it will also be particularly
devastating to these Checkered Beetles which live within the burrows in
the trees themselves." 



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