| DNA
barcoding may help prevent
invasive species disasters
By Colleen Boicey
OTTAWA —
Jean-François Landry
does a lot of detective work. He is a systematist and
as such, he classifies small moths in order to determine
their natural relationships.
Specimens are sent to his Agriculture
and Agri-Food Canada laboratory in Ottawa from all over
Canada. They arrive from places like Canadian border
inspection points, agriculture sites and even backyards.
An increase in global trade has seen a
corresponding increase in alien invasive species.
Insects are very adaptable. For example,
the invasive Emerald Ash Borer and the Asian Longhorned
Beetle were imported inside the planks of wooden crates;
both are having devastating effects on trees. "Most
pest species are introduced species," he says.
"Insects don't respect borders."
It is critical that Landry identify these
specimens to determine if they are a threat to the Canadian
agriculture industry and environment
This need to identify species and to
understand their evolution, natural history, distribution
and classification, are the reasons why Landry is involved
in the Canadian Barcode of Life Network. "If we
don't know what's out there, how can we prevent things
from happening?" he says.
The network started up in May 2005 with
31 researchers at Canadian universities, governmental
laboratories and museums. It's part of a global project
to establish genetic barcodes, or standard genetic profiles,
for the world's species.
There are an estimated 10 million insects
world-wide with about 75,000 in Canada. Barely half
of the Canadian species are documented, Landry says.
That could change.
In future, for instance, a barcode system
could mean workers in fields would be able to identify
species with hand-held devices similar to those used
in supermarkets.
How the barcoding process works
Landry sends a leg from the moth to the
lab. One piece of the same gene of each of the species
is isolated through a chemical reaction.
| 'If we don't know
what's out there, how can we prevent things from
happening?' |
The genetic material is then amplified
and the order of the DNA letters in the gene is recorded
as the moth’s barcode. It is then classified with
the characteristics of that moth.
Currently, there are 13,000 specimens
of individual moths in the North American database.
Of these, 1,900 species have been distinguished, 1,750
have been named the remaining 150 are in the process
of being identified, Landry says.
So far, the system has worked. "In
tests, it works remarkably well,"Landry says.
Identifying species by their DNA is better
for sorting; traditional identification methods are
more time consuming because moths have to be examined
under a microscope for diagnostic fine structures, such
as hairs and hooks.
What'smore, many species of moths can
only be distinguished by the shape of their genitalia,
an adult characteristic, which must be micro-dissected
for examination.
But, DNA recognition can identify a moth
at any stage of its life:
A larvae sent to Landry could not be identified
because it could not be matched to species and did not
produce an adult moth. Later, he received a similar
sample which produced a moth. He sent both the moth
and the larvae to have the DNA compared. There was a
match.
DNA barcodes will speed up identifications
and alleviate the demand on the few specialists available
to conduct expert identification, says Landry, who is
the only micro moth specialist in Canada.
Taking off the leg of a moth and sending
it to a lab for DNA analysis is not nearly as complex
nor time consuming as the skilled dissections and comparisons
he routinely makes.
Barcoding not always accurate
Barcoding is not without controversy.
. For instance, the DNA extraction does not work as
well on older specimens.
"We know there are cases where it's
not going to work," Landry says. "That should
not deter us. We should say let's test the limit."
Traditional methods of retrieving data
on insects are in the form of collections like the Canadian
National Collection of Insects, Arachnids and Nematodes
(CNC), at the Central Experimental Farm, where Landry's
office is.
| 'There are a lot
of gaps in our knowledge, it's the systematist's
job to fill those gaps.' |
The century-old world renowned collection
is contained in 1,400 steel cabinets and estimated to
have 16 million specimens.
The CNC serves as an active repository
of voucher specimens and as a primary source of data
for the work of systematists.
The moths Landry works with are neatly
arranged with collecting data under glass on wooden
shelves stored in cabinets.
Barcoding will not replace
tradition
This method of identifying moths by their
structure and throughdissection is something DNA identification
will not replace because species are continually evolving
and adapting, and variations are continually discovered.
“You can't say just from the DNA
if you've got something new,” he says. “It's
a necessary piece of work to examine morphology. You
have to gauge the barcode against something else in
order to interpret it.”
Detective work has always been part of
Landry's life. Even as a child, he collected insects.
Now he can access the collection at the CNC, a collection
he will continue to grow.
"There are a lot of gaps in our knowledge,
it's the systematist's job to fill those gaps,"
he says. "It's nice to have as broad of a sample
as possible. It's extremely useful and necessary."
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