The Rural Voice, 1988-07, Page 18BIOLOGICAL PEST CONTROL:
A GREAT IDEA
When will its time come?
D
oes biological control have a
great future for the manage-
ment of pests in Canadian
agriculture?
Yes.
But that future will be a long time
coming, according to two prominent
researchers in the field. Dr. Oswald
Morris of the Agriculture Canada
Winnipeg Research Station, and Dr.
John Laing, an environmental biolo-
gist at the University of Guelph, be-
lieve that the development of biologi-
cal alternatives to chemical control is
absolutely necessary, but have doubts
about how far modern agriculture will
go in supporting or adopting them.
Why do we need biological control
methods? The answer is relatively
straightforward and familiar. Agri-
cultural pests have been controlled
almost exclusively with chemical
insecticides since the development of
insecticides in the 1940s. Insecticides
are cheap and effective against a broad
range of pests, and the predominant
strategy has been to kill every possible
pest on the crop with heavy and
frequent applications.
But the heavy use of chemicals
has detrimental effects in the long run,
both for the crop and the environment.
Broad-spectrum chemicals destroy the
natural predator/parasite complex of
pests and potential pests in the crop.
Previously minor pests can become
major when freed from natural con-
straints. And when pests become
resistant to the chemicals used against
them, their numbers explode because
there are few natural enemies to
control them. The result? Either new
by Ian Wylie-Toal
chemicals must be developed or the
strength and frequency must be
increased.
The problems created by chemical
control can be quite severe: in the late
1950s, some apple -growing areas of
the U.S. had to introduce new miti-
cides every three to five years as the
mites became resistant. Eventually
growers ran out of options. In the
1960s, some Lower Rio Grande cotton
growers were spraying a complex of
Dr. David Suzuki:
The use of "powerful
poisons that kill all
exposed insects is no
more 'management' of
pests than killing every-
one in New York City
would be managing
urban crime."
resistant pests 15 to 20 times in a
season and still losing their crop. By
1977, 24 species of insects and mites
on cotton were resistant to one or
more chemicals.
Broad-spectrum chemicals also
wreak havoc with non -target life,
killing the thousands of beneficial and
benign invertebrates that live in the
crop. These invertebrates form the
base of a complex food chain, eating
each other, pollinating plants, and
providing food for mammals, birds,
and fish. Remove the insects, and the
system falls apart. Pesticides also
have a nasty habit of showing up
where they are not wanted, drifting
into bush and residential areas,
washing into the soil and rivers where
they appear in drinking water, and
remaining on the food we eat.
It's not surprising, then, that many
people believe that chemicals are an
imprecise and dangerous way to
control pests.
Dr. David Suzuki, writing about
the folly of chemical pest control in
the Globe and Mail, says that the use
of "powerful poisons that kill all
exposed insects is no more 'manage-
ment' of pests than killing everyone
in New York City would be managing
urban crime."
Dr. Robert Lamb and Dr. William
Turnock, analyzing the economics of
controlling flea beetles with insecti-
cide in a paper published in The
Canadian Entomologist (Vol. 114,
827-40), say that "continued applica-
tion of such large quantities of insect-
icide might have deleterious environ-
mental and social consequences and
increase the likelihood of pest resis-
tance ... We conclude that insecticidal
control of flea beetle damage can be
an effective and economically sound
method for preventing losses, but ... is
saving Less than half of the crop which
requires protection and does so at a
substantial cost to the producers."
The work of Drs. Morris and Laing
is aimed at circumventing these prob-
lems by introducing or augmenting a
control system using natural means.
Dr. Laing, a director of the Biological
Control Lab at the University of
16 THE RURAL VOICE