The Rural Voice, 1988-02, Page 36AGRICULTURAL
RESEARCH UGLY RESEARCH
The Good, the Bad, the Ugly, and the Incomprehensible
I
n terms of economic loss on
the farm, the flea beetle ranks
high among North American
pests. A study published in 1982
estimated that flea beetles cost farmers
$12 million for insecticide application
and destroyed up to eight per cent —
about $72 million worth — of the
canola crop.
This level of crop destruction is
equal to that caused by the boll wee-
vil, the most serious agricultural pest
in the U.S., although the dollar value
of the canola destoyed is much less
than the value of the cotton lost to the
weevil. The financial loss caused by
the flea beetle is nearly equal to the
loss caused by the alfalfa weevil,
another serious pest in the U.S.
Yet the same study also points out
that the flea beetle has received much
less research attention than these other
pests: fewer than 15 research papers
on the pest were published in Western
Canada (where much of the research
on the flea beetle is carried out) be-
tween 1972 and 1982.
On the surface, this is a curious
situation. A pest that causes so much
loss should get a great deal of atten-
tion. Instead, it looks as though the
flea beetle is being ignored.
This apparent discrimination
against the flea beetle problem has
some basis in fact. Flea beetles are
one of the ugliest research problems
to come along in years. Their habits
make them difficult to control in the
field. They are also hard to work with
in the lab, so any research on them
becomes a frustrating and complicated
matter. Many scientists working in
by Ian Wylie-Toal
agriculture want nothing to do with
flea beetles; the headaches are too big
and the rewards too few to excite any
but the most determined workers.
What is it about flea beetles that
makes them such an ugly subject for
research? After all, they are only
insects, and many different insects
have been studied successfully for
years. Are flea beetles that different
from all the rest?
Once again, as is the case with so
much biological research, the answer
is yes and no. No, flea beetles are not
much different from other insects.
The adult beetles overwinter in bush
and leaf litter, emerge in the spring to
feed, then lay eggs and die. The eggs
are laid in the soil around plants in the
brassica family (canola, mustard,
cabbage) and the larvae live in the
soil, feeding on the plant roots. In late
summer, a new generation of adult
beetles emerges, feeds until fall, then
goes into hibernation, starting the
cycle again. This is a common type
of insect life cycle, especially among
beetles. Neither are the flea beetle's
physiology, method of eating, or way
of breathing or laying eggs essentially
different from other insects'.
But at the same time, yes, flea
beetles are different. First, the two
main species of flea beetles were
accidentally introduced from Europe,
so the population does not have a
normal predator/parasite/disease com-
plex to keep it in balance. Flea beetles
are also highly mobile insects, and
have used that mobility to cash in on
the expanded acreage seeded to canola
in the past 20 years or so. The in-
creasing numbers of beetles have no
difficulty finding new food sources.
Their mobility also makes them
difficult to spray; the insects simply
get up and leave when a field is dis-
turbed. New insects will rapidly re -
colonize a sprayed field as well, so
spraying for flea beetles is not a com-
mon practice. Instead, because the
adults are active and feeding when the
seeds are germinating, the seeded crop
is treated with a long-lasting insec-
ticide which gets the seedlings through
the dangerous time. The timing of the
flea beetle's feeding is what makes it
so damaging. An untreated crop will
be eaten voraciously and the small
plants soon die. Many farmers who
complain of poor seed germination are
in fact victims of flea beetles. The
crop germinated and emerged, and
was eaten down before the farmers
were aware of it.
Flea beetles are a perennial prob-
lem, so the seed must be treated every
year. As a control method, this is
effective but not ideal. The insecti-
cides used are costly and often severe-
ly toxic to both people and insects.
34 THE RURAL VOICE