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Biosecurity strategies to control invertebrate invaders


 
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Inspection of boats and containers in port for exotic insects and other species is an obvious measure used by the Australian Quarantine and Inspection Service (AQIS) to maintain our biosecurity. However, entomologist, Luke Halling, is part of an AQIS team that looks at other pathways (think wind dispersal and foreign vessel activity) for unwanted species to take hold.     

 

 
Above: beetle larva boring in foreign fishing vessel remains
Working from their base in Broome on the Kimberley coast, they look for exotic pests along our northern coastline, acting as an early detection and warning system.
Luke collects and identifies insects which may pose a threat to Australia’s agriculture and environment as part of an AQIS team. Wind dispersal of unwanted species is still a risk and the establishment of farms creates more receptive areas for insects. Coupled with this is the rise in farmland in countries to our north, meaning that more insects are moving closer to Australia. There is also increasing activity from foreign fishing vessels that pose risks through termites and borers on board, along with mosquitoes in drinking water. Luke’s team manages trapping programs. They have traps for fruit flies and biting midges (which can spread disease through cattle) along the northern Australian coast from Broome to Cairns.
Left: Asian Tiger Mosquito from an Indonesian water bottle

 
Below right: Luke collecting termites from the remains of a foreign fishing vessel    
For the fruit flies, the traps are placed around suitable areas such as tropical fruit farms, while cattle waterholes and cattle yards are good places for biting midge traps.
Active surveillance is also carried out for the things that can’t be trapped and which could affect either agriculture or the natural environment. Genetic analysis of biting midges trapped on our shores shows that some come from populations outside of Australia, blown across in the humid monsoonal winds.

 
There are established biting midges in Australia which spread a virus called blue tongue in cattle across the north, hampering cattle exports from those areas.     
Fortunately the midges only survive in the warmer north, so they are not a risk to cattle elsewhere in Australia. Unfortunately, however, there are other biting midges from our northern neighbours and it is unknown whether they are limited to certain climates so it is far safer to monitor them.

 
Some mosquitoes are also vectors of diseases affecting humans. The Asian tiger mosquito and the dengue fever mosquito both pose risks and while dengue fever is around places like Cairns it is not established in the more isolated northern parts of Western Australia or the Northern Territory. Vigilance is required, however, as both these mosquitoes lay eggs in containers which can wait for many months for the rain needed to trigger the development of larvae.
The trapping program for mosquitoes involves the community in remote places. This work is carried out by indigenous rangers, who trap the larvae and send them on for identification.
This monitoring improves the likelihood of catching any exotic incursion quickly and in that way, improves chances of eradication.
Debris is another possible carrier of unwanted species. Exotic termites, such as dry wood termites can end up on our shores via wooden debris from boats.
Left: Tyre traps are used by AQIS to monitor for mosquito larvae

 
The task of monitoring the length of Australia’s vast northern coastline is made easier by knowledge of the tides, making predictions of where things might wash ashore more accurate.     
In addition, certain areas are known to be used by foreign fishing vessels, so that also aids surveillance. The AQIS team effort is supported by collaborations with the CSIRO and state departments, such as the one in New South Wales that is looking at the genetic variations in populations of biting midges. The small AQIS laboratory at Broome is fitted with microscopes and digital cameras, allowing magnified photos to be sent to specialists for further identifications. Live video imaging is also being looked at, enabling collaborative identification of species, with experts from interstate or around the world.

 
Not surprisingly, the extensive fieldwork has turned up some interesting finds. One was of thrips, never previously described and anotherwas a species of weevil. Other finds include described species that have not been known to inhabit a particular area. A white fly, for instance, known to live on native sandalwood in Queensland and South Australia has jumped onto commercial sandalwood crops in the Ord River.
Right: Luke with farmers who assist AQIS by trapping biting midges in remote areas

 
The success of the whole operation around insects is testimony to the care that AQIS takes in its work.

Images provided by Luke Halling from AQIS
Text: V.B. December 2009

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AQIS has a program of Indigenous engagement across Australia's Top End Ballast water

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