228
Biological invasions and the homogenization of faunas and fl oras
Airline t raffi c
International air travel has been recently pinpointed as a signifi cant factor in the movement of
economically damaging pest species and infectious diseases (Tatem, 2009 ). Among others, the
Mediterranean fruit fl y Ceratitis capitata has been consistently imported in airline baggage (Liebhold
et al. , 2006 ), plant pathogens are often found in air cargo (McCullough et al. , 2006 ) and disease -
carrying mosquitoes have survived long haul fl ights in aircraft cabins (Lounibos, 2002 ). Far - removed
regions with similar climates have now been suddenly linked by a busy fl ight schedule, which has
resulted in an elevated risk of foreign invasions.
This risk, however, depends greatly on the time of year. Tatem and Hay (2007) identifi ed an ‘ invasion window ’ across the global air network from June to August, when climatic conditions in regions
linked by long - haul routes are most similar to one another and the higher number of fl ights increases
the chances of exotic species hitching a ride to somewhere new. With expected increases in global
trade and travel (Perrings et al. , 2005 ; Hulme, 2009 ), opportunities for such extreme hitchhiking
through the world airline transportation and shipping network look set to increase further (see trend
in Figure B9.1b ).
Figure B9.1a (a) The frequency of commercial shipping traffi c along shipping routes around the world, ranging
from low (blue) to high (red). From Halpern et al. (2008) . (b) Global hotspots for biological invasion from ballast
water, ranging from low (blue) to high (red). From Drake and Lodge (2004) . (See Plate B9.1a for a colour version of
these images.)
Figure B9.1b Trends in global shipping cargo volumes and air freight, 1970 – 2005. From Hulme (2009) .
Biological invasions and the homogenization of faunas and fl oras
Airline t raffi c
International air travel has been recently pinpointed as a signifi cant factor in the movement of
economically damaging pest species and infectious diseases (Tatem, 2009 ). Among others, the
Mediterranean fruit fl y Ceratitis capitata has been consistently imported in airline baggage (Liebhold
et al. , 2006 ), plant pathogens are often found in air cargo (McCullough et al. , 2006 ) and disease -
carrying mosquitoes have survived long haul fl ights in aircraft cabins (Lounibos, 2002 ). Far - removed
regions with similar climates have now been suddenly linked by a busy fl ight schedule, which has
resulted in an elevated risk of foreign invasions.
This risk, however, depends greatly on the time of year. Tatem and Hay (2007) identifi ed an ‘ invasion window ’ across the global air network from June to August, when climatic conditions in regions
linked by long - haul routes are most similar to one another and the higher number of fl ights increases
the chances of exotic species hitching a ride to somewhere new. With expected increases in global
trade and travel (Perrings et al. , 2005 ; Hulme, 2009 ), opportunities for such extreme hitchhiking
through the world airline transportation and shipping network look set to increase further (see trend
in Figure B9.1b ).
Figure B9.1a (a) The frequency of commercial shipping traffi c along shipping routes around the world, ranging
from low (blue) to high (red). From Halpern et al. (2008) . (b) Global hotspots for biological invasion from ballast
water, ranging from low (blue) to high (red). From Drake and Lodge (2004) . (See Plate B9.1a for a colour version of
these images.)
Figure B9.1b Trends in global shipping cargo volumes and air freight, 1970 – 2005. From Hulme (2009) .