Agriculture Victoria scientists have developed a new method to identify pests in traps that is more time efficient and less destructive, enabling scientists to keep insects intact for biosecurity purposes.
The scientists are using ‘metabarcoding’ – a specialised technique that uses a short section of DNA from the insects and develops a specific barcode for this species. It then compares it with a reference library of barcodes to identify the species, in the same way a supermarket scanner uses a barcode to identify an item.
This technique allows the simultaneous identification of many species within the same sample from a trap, which can have up to 1000 insects inside it.
Agriculture Victoria has helped to pioneer the use of metabarcoding for biosecurity surveillance in Australia and was one of the first groups to apply the specialised technique to mosquito surveillance.
Metabarcoding is the focus of current research aimed at detecting and monitoring a wide range of endemic and exotic plant and animal pests ranging from tephritid fruit flies to avian influenza virus.
Agriculture Victoria research scientist Dr Mark Blacket said the primary aim of this research is to find a more efficient way to deal with the major bottleneck caused by having to identify individual pest species in among large numbers of non-target trapped insects caught through surveillance programs.
“Currently the traps are mainly processed manually, and our taxonomists identify each insect visually through microscope examination, which is very time-consuming and highly specialised work, particularly when traps catch large numbers of insects,” Dr Blacket said.
The Agriculture Victoria team has recently developed a new DNA extraction method, and tested the non-destructive method on mock traps, before applying the technique to insects trapped near potato and vegetable crops, in surveillance for Russian wheat aphid and Tomato potato psyllid.
“The new extraction method means that instead of crushing all the insects to get their DNA the insects are left intact, keeping them for further examination if something unusual is detected in the DNA sequences,” Dr Blacket said.
This research demonstrated that metabarcoding is sensitive enough to identify a single specimen in a large trap, as the research team identified a Russian wheat aphid that traditional morphological detection missed.
The findings showed metabarcoding can not only detect one pest insect in a trap containing 1,000 specimens, but it can also be used to potentially identify all the species in a trap which is really useful for biodiversity studies.
Metabarcoding can enhance biosecurity by quickly and effectively processing large numbers of traps from a wide area so that exotic pests can be tracked and eradicated when they are first detected.
Additionally, this method can produce a physical specimen of any detected pest, which is necessary if a pest detection has financial consequences such as halting trade or restricting exports.
For more information about this research visit the Scientific Reports website