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IN THIS EDITION OF THE FRONT LINE,
WE INVESTIGATE THE IMPACT OF THE
COLORADO POTATO BEETLE OVERSEAS
AND EXPLAIN WHY IT HAS BEEN
SUCH A DESTRUCTIVE PEST ACROSS
COUNTRIES IN NORTH AMERICA,
EUROPE AND PARTS OF ASIA.
Colorado potato
beetles march east
The Colorado potato beetle
(CPB, Leptinotarsa
decemlineata) is regarded as
one of the greatest potato pests.
It is incredibly destructive,
broadly spread around the
world and highly resistant to
insecticides. Around 56 active
chemicals are now of limited
effectiveness against the CPB.
The beetle is capable of
stripping an entire potato plant
of all foliage, which can kill
young plants or result in a
50 per cent reduction in yield
for a crop. It has spread across
North America, Europe and
much of Asia and is able to
survive in extremely hot and
cold environments.
Part of the difficulty in
controlling CPB is that it
spends a lot of its life
underground, either
overwintering or transforming
into adults. In some cases this
can last for two years.
In the warm weather, the
beetles emerge, mate, feed and
lay eggs. Once they hatch,
the young (larvae) constantly
feed on potato leaves and
then bury into the ground to
later emerge as adults.
Researchers have determined
that a female is able to lay
between 500 and 1,000 eggs,
so the numbers in a crop can
be significant. As adults can
each eat 10cm² of potato leaf
per day, and the beetles tend
to emerge from the soil at the
same time in spring, there is
significant potential for massive
damage to potato crops.
Temperature and hours of
light help to determine the
number of generations of
CPB that can develop per
year. Therefore, the climate of
the southern half of Australia
would be quite supportive of
CPB reproduction.
Along with intercrop
dispersal, adults are able to
migrate and fly up to over 100
kilometres to find new food
sources and mates. Additionally,
they are able to hitchhike on
transportation of plant material
and survive in sea water for
several days until they wash up
on land, further increasing their
potential for spread.
The beetle originated in Mexico,
where it lived primarily on plants
native to the area. From there,
CPB began to spread when
it came into contact with the
potato crops of early American
setters in the mid-19th Century.
It completed its spread across
the entire North American
continent by 1919. Despite
quarantine measures and
successful earlier eradications,
it established itself in France
by 1922. From there it moved
eastward across Europe and
then Asia. By 2010, CPB had
been found in 38 counties and
cities throughout China.
The CPB spread has followed
the Northern Hemisphere’s
temperate zone eastward, but
the beetle is able to establish
itself in quite extreme hot and
cold latitudes. Distribution
between 15° and 60° north
has been recorded. If it
were to reach the Southern
Hemisphere, then large parts of
Australia would offer a suitable
environment for the beetle to
cause destruction.
Adult Colorado potato beetle. Image courtesy of
Clemson University–USDA Cooperative Extension
Slide Series,
Colorado potato beetle eggs. Image
courtesy of Whitney Cranshaw, Colorado
State University,
Image courtesy of Bruce Watt,
University of Maine,