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Technology

Laboratory testing – from bucket to bench

DNA testing is used on the eggs you have collected to discover what species of mozzie is contained inside.

Once the eggs have been counted, your dried egg collection strip (or 'ovistrip') is taken to the lab, where the eggs are hatched and the DNA from 1-day old mozzie wrigglers is tested.

We use very sensitive ‘polymerase chain reaction’ (PCR) testing that will produce a signal if it finds Aedes aegypti or Aedes albopictus mozzie species.

Instead of taking up to three weeks to identify an adult mozzie, this testing can find one specific mozzie of a certain species, from among 1,000 to 5,000 different mozzies in just 3 days!

1. Eggs are prepared for hatching

Each trimmed ovistrip is added to a clean box in the lab. Multiple strips can be added together if we want to know about a street, suburb or whole city rather than just one house.

Pure water is added on top and the box is set aside overnight for the eggs to hatch.

Prepare for hatching

2. Eggs hatch

How many eggs have hatched? We can check that under the microscope. You might be able to see the hatched eggs – one end is missing its ‘lid’

Under the microscope

3. Wrigglers come out

The next day the box is filled with hatched wrigglers. These are called the '1st instar phase I eth mosquito lifecycle'.

Wrigglers hatch

4. DNA testing time

A positive result for one or the other mozzie species appears as a detectable fluorescence signal above a threshold in our PCR test, as shown by the table below.

The signal only appears if the DNA we test for is present.  If the DNA is present, the signal will grow each PCR cycle until it can be detected. Without PCR’s amplification, there is too little DNA to detect in a single egg.

Last updated 4 June 2018
Last reviewed 4 June 2018

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