Stowaway mozzies enter Australia from Asian holiday spots – and they’re resistant to insecticides

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We might not be able to use common insecticides to kill mosquitoes that arrive from other countries.

Tom Schmidt, University of Melbourne; Andrew Weeks, University of Melbourne, and Ary Hoffmann, University of Melbourne

Planning a trip to the tropics? You might end up bringing home more than just a tan and a towel.

Our latest research looked at mosquitoes that travel as secret stowaways on flights returning to Australia and New Zealand from popular holiday destinations.

We found mosquito stowaways mostly enter Australia from Southeast Asia, and enter New Zealand from the Pacific Islands. Worse still, most of these stowaways are resistant to a wide range of insecticides, and could spread disease and be difficult to control in their new homes.

Read more:
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Secret stowaways

Undetected insects and other small creatures are transported by accident when people travel, and can cause enormous damage when they invade new locations.

Of all stowaway species, few have been as destructive as mosquitoes. Over the past 500 years, mosquitoes such as the yellow fever mosquito (Aedes aegypti) and Asian tiger mosquito (Aedes albopictus) have spread throughout the world’s tropical and subtropical regions.

Dengue spread by Aedes aegypti mosquitoes now affects tens to hundreds of millions of people every year.

Read more:
Explainer: what is dengue fever?

Mosquitoes first travelled onboard wooden sailing ships, and now move atop container ships and within aircraft.

Adults in your luggage

You probably won’t see Aedes mosquitoes buzzing about the cabin on your next inbound flight from the tropics. They are usually transported with cargo, either as adults or occasionally as eggs (that can hatch once in contact with water).

It only takes a few Aedes stowaways to start a new invasion. In Australia, they’ve been caught at international airports and seaports, and in recent years there has been a large increase in detections.

Aedes aegypti mosquito detections per year at Australian international terminals – passenger airline terminals in white; seaports or freight terminals in black.
Tom Schmidt, Author provided

Read more:
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In our new paper, we set out to determine where stowaway Aedes aegypti collected in Australia and New Zealand were coming from. This hasn’t previously been possible.

Usually, mosquitoes are only collected after they have “disembarked” from their boat or plane. Government authorities monitor these stowaways by setting traps around airports or seaports that can capture adult mosquitoes. Using this method alone, they’re not able to tell which plane they came on.

But our approach added another layer: we looked at the DNA of collected mosquitoes. We knew from our previous work that the DNA from any two mosquitoes from the same location (such as Vietnam, for example) would be more similar than the DNA from two mosquitoes from different locations (such as Vietnam and Brazil).

So we built a DNA reference databank of Aedes aegypti collected from around the world, and compared the DNA of the Aedes aegypti stowaways to this reference databank. We could then work out whether a stowaway mosquito came from a particular location.

We identified the country of origin of most of the Aedes aegypti stowaways. The majority of these mosquitoes detected in Australia are likely to have come from flights originating in Bali.

Here’s where the Aedes aegypti mozzies come into Australia and New Zealand from.
Tom Schmidt, Author provided

Now we can work with these countries to build smarter systems for stopping the movement of stowaways.

As the project continues, we will keep adding new collections of Aedes aegypti to our reference databank. This will make it easier to identify the origin of future stowaways.

New mosquitoes are a problem

As Aedes aegypti has existed in Australia since the 19th century, the value of this research may seem hard to grasp. Why worry about invasions by a species that’s already here? There are two key reasons.

Currently, Aedes aegypti is only found in northern Australia. It is not found in any of Australia’s capital cities where the majority of Australians live. If Aedes aegypti established a population in a capital city, such as Brisbane, there would be more chance of the dengue virus being spread in Australia.

The other key reason is because of insecticide resistance. In places where people use lots of insecticide to control Aedes aegypti, the mosquitoes develop resistance to these chemicals. This resistance generally comes from one or more DNA mutations, which are passed from parents to their offspring.

Read more:
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Importantly, none of these mutations are currently found in Australian Aedes aegpyti. The danger is that mosquitoes from overseas could introduce these resistance mutations into Australian Aedes aegpyti populations. This would make it harder to control them with insecticides if there is a dengue outbreak in the future.

In our study, we found that every Aedes aegpyti stowaway that had come from overseas had at least one insecticide resistance mutation. Most mosquitoes had multiple mutations, which should make them resistant to multiple types of insecticides. Ironically, these include the same types of insecticides used on planes to stop the movement of stowaways.

Other species to watch

We can now start tracking other stowaway species using the same methods. The Asian tiger mosquito (Aedes albopictus) hasn’t been found on mainland Australia, but has invaded the Torres Strait Islands and may reach the Cape York Peninsula soon.

Worse still, it is even better than Aedes aegypti at stowing away, as Aedes albopictus eggs can handle a wider range of temperatures.

A future invasion of Aedes albopictus could take place through an airport or seaport in any major Australian city. Although it is not as effective as Aedes aegypti at spreading dengue, this mosquito is aggressive and has a painful bite. This has given it the nickname “the barbecue stopper”.

Beyond mosquitoes, our DNA-based approach can also be applied to other pests. This should be particularly important for protecting Australia’s A$45 billion dollar agricultural export market as international movement of people and goods continues to increase.

Read more:
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The Conversation

Tom Schmidt, Research fellow, University of Melbourne; Andrew Weeks, Senior Research Fellow, University of Melbourne, and Ary Hoffmann, Professor, School of BioSciences and Bio21 Institute, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.


Dangar Falls 360

The Peripatetic Ponderings of a Passing Person

During my break from Blogging I was able to get away for some time out. I headed off to one of my favourite spots, relatively close to here (about 3.5 to 4 hours drive, which is fairly close for Australia), Dorrigo. Dorrigo National Park is near Dorrigo – in fact it is just 2km out of town. It’s a great place and I’ll be posting some photos (and possibly video also) from the visit over the next week or so. During my visit I stayed at Dorrigo Mountain Resortjust out of Dorrigo and close by the national park. I stayed in a fairly basic cabin for two nights, which though it wouldn’t meet the standards set by most people (and I wouldn’t blame them or judge them for that) for a place to stay, I did view it as just somewhere to stay and sleep, choosing to spend…

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Planning and Organising a Holiday Using Evernote

The link below is to an article that looks at planning and organising a holiday by using Evernote.

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Red Centre Holiday 2016: Day 11 – Watarrka National Park, Northern Territory

It was a fairly easy day for my last day at Watarrka National Park. All I had left to do was walk the very short Kathleen Springs Walk, which only took about 1 hour to complete. It was a reasonably short drive to this section of Watarrka National Park and the walk itself was also very easy. Still, it was an early start considering just how little I had to do.

ABOVE: View from the Beginning of the Walk

ABOVE: Old Cattle Yards   BELOW: Wildflowers

ABOVE: Waterhole at the End of the Gorge   BELOW: Old Cattle Yards

Having returned to camp following the walk, I once again had a very early main meal for the day while the campsite was quiet and found that again there was no water for a lengthy period, and once again no communication from site management that the water was being turned off. Eventually I was able to clean up my gear and settle down for a lazy afternoon reading and chatting. I also made sure I had ready everything I could for the big move to Alice Springs the next day, which was going to start very early the following morning.

ABOVE & BELOW: Wildflowers

The distance travelled on this day was 52 km – giving me a total of 3516 km for the whole trip to this point.

ABOVE: Camp Site at Kings Canyon Resort

When it got dark, once again, it was the usual ‘house keeping’ before bed – updating the daily journal, reviewing the holiday budget, and without the Internet, getting the photos ready to upload.

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Red Centre Holiday 2016: Day 10 – Watarrka National Park, Northern Territory

It was a fairly straight-forward type of day today. It was an early, short drive to Watarrka National Park from Kings Canyon Resort, where I did the Kings Canyon Rim Walk. The Kings Canyon Rim Walk is a spectacular exploration of the the area above the gorge and also descends into the gorge to an area known as ‘The Garden of Eden.’ It is a 6km return walk, with some moderate to difficult sections, especially at the beginning with the climb to the gorge rim. Surprisingly the walk was completed in about 3 hours, even allowing for a bit of sightseeing along the way.

ABOVE & BELOW: Scenery from the Kings Canyon Rim Walk

ABOVE & BELOW: Scenes from the Kings Canyon Rim Walk

Having completed the walk and once again not being able to use the free wifi point at Watarrka National Park I travelled back to Kings Canyon Resort for a very early main meal (while the resort was fairly quiet) and to spend a relaxing afternoon chatting with other campers and reading. A couple of guys I had met at Uluru turned up for a couple of days, so it was good to chat with them a bit also.

ABOVE & BELOW: The Garden of Eden

The distance travelled on this day was 19 km – giving me a total of 3464 km for the whole trip to this point.

When it got dark, once again, it was the usual ‘house keeping’ before bed – updating the daily journal, reviewing the holiday budget, and without the Internet, getting the photos ready to upload.

ABOVE: Scene from the Kings Canyon Rim Walk

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Red Centre Holiday 2016: Day 9 – Yulara to Watarrka National Park, Northern Territory

It was an early start as I headed of for Watarrka National Park, for a morning that was going to be spent driving and then hopefullly setting up my campsite, before heading off for a quick walk at Watarrka National Park. My first stop was at Curtain Springs for a quick top up of the fuel, knowing that fuel was going to be expensive at Kings Canyon Resort. So after that stop it was basically nothing but driving straight to Watarrka National Park and the Kings Canyon Resort.

ABOVE: Mount Conner as Seen Along the Way to Watarrka National Park

When I arrived there were no powered campsites available as the place was pretty busy and booked out. It turned out that the Variety Bash was in the area and staying at the resort that night. It was a very crowded scene and somewhat chaotic. I managed to grab a campsite without power, set up and decided to escape to the national park for a while.

At Watarrka National Park I noticed that there was a free wifi hot spot at a shelter at the beginning of the walks. This seemed like a good thing, given that I had no Internet access at the resort. However, this proved to be near useless as nothing was able to load. It was pretty bad when more than one person was trying to access it, let alone a whole group of people. It barely worked for one! So that proved to be of no real benefit to me.

ABOVE & BELOW: Wildflowers were a feature of Kings Creek Walk

ABOVE: Wildflowers were a feature of Kings Creek Walk   BELOW: Kings Creek Walk

I decided I didn’t really have the time to do the rim walk and actually enjoy it at the same time, so I decided to start on that one early the next morning. Instead I chose to do the Kings Creek Walk, which was a comfortable 2 km return walk following Kings Creek into the canyon. It proved to be a far better walk than I had anticipated, so given I had a bit of time to play with I took my time and really enjoyed it. There wasn’t a lot of water around, but it was still a great experience and I did find a waterhole just beyond the end of the walk.

ABOVE: View From the Kings Creek Walk

ABOVE & BELOW: Kings Creek

ABOVE: Budgerigars Nesting Along Kings Creek

With the completion of the walk I returned to the resort to find I was unable to get a park next to my tent, which to be honest, really annoyed me. The resort has very poor parking facilities for campers – in fact, there was a lot about the resort that I found disappointing. The camp kitchen was terrible and the equipment poorly maintained, as was the case in both the laundry and ammenities block. Indeed, for a couple of days during my stay there was no water available across the site for hours at a time and no communication provided for visitors as to what was happening. I guess when you have a monopoly on services you can get away with pathetic service and conditions. Then of course there were the prices in the shop and the fuel price ($2.02 a litre for ULP). When I surveyed the shop my mouth dropped at the prices. It was $6.50 or $7.50 for a 1.25 litre bottle of coke and around $8.00 for a packet of Tim Tams. Everything was priced highly. It became a bit of a talking point around the tents each evening, with various plans for opening pop-up shops at the entrance of the park to sell various items at reduced prices.

I booked in and paid for 3 nights when I arrived and soon realised that I had made a mistake. Two nights would have been more than sufficient to do all that I had planned at Watarrka National Park – Kings Creek Walk, Kings Canyon Rim Walk and Kathleen Springs. So I planned to do one each day and then do some reading each afternoon. I also got to know a few people around camp which helped to pass the time also, which helped as I do like to get on with things and sitting around while travelling seems to be such a waste of time, especially when it took me so long to get to the Territory. I like to get to see as much as I can in the time I have available, so that extra night proved a very frustrating thing to me.

The distance travelled on this day was 320 km – giving me a total of 3445 km for the whole trip to this point.

When it got dark, once again, it was the usual ‘house keeping’ before bed – updating the daily journal, reviewing the holiday budget, and without the Internet, getting the photos ready to upload. Then it was off to bed for an early start the next morning, with the Kings Canyon Rim Walk before me.

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Visit the Red Centre Holiday 2016 web page at:

Red Centre Holiday 2016: Day 8 – Uluru-Kata Tjuta National Park, Northern Territory

It was a much later start today, with just some short walks to knock over before a fairly relaxing afternoon. Before I started the walks I stopped at the Uluru Sunset Viewing Area to collect a couple of shots of Uluru.

ABOVE: Uluru in the Early Morning

The first of the two walks for this morning was the Liru Walk. The Liru Walk connects Uluru with the Cultural Centre and can be walked from either location. I started at Uluru because it would also be the starting point for the Mala Walk, the second walk I would be doing this morning. The Liru Walk is a 4 km return walk which is flat and easy, making its way through the low woodland and wildflower covered region between the Rock and the Cultural Centre. It was a visual feast of wildflowers during my visit.

ABOVE & BELOW: Wildflowers of the Liru Walk

With the Liru Walk completed, I headed off to repeat the Mala Walk, which I had completed as part of the Uluru Base Walk 2 days before. I wanted to do the walk again because it was very crowded on the previous occasion and Uluru seemed much quieter at the moment and it indeed proved so. Still, there were some ‘yahoos’ about and I did mention something to someone about how all that spoiled the experience of the place. Little did I know at the time that the woman I mentioned that to was the mother of the teenagers carrying on like idiots and they were soon told to quieten down. I think all present were pleased with the result. I suspect the Mala Walk is probably the best part of the area around Uluru itself, with its natural beauty and its cultural importance also, it being an important location for the Aboriginal people.

ABOVE: Scenery from the Mala Walk   BELOW: Rock Art on the Mala Walk

ABOVE & BELOW: Kantju Gorge – Part of the Mala Walk

The distance travelled on this day was 43 km – giving me a total of 3125 km for the whole trip to this point.

When it got dark, once again, it was the usual ‘house keeping’ before bed – updating the daily journal, reviewing the holiday budget, checking in on social media, and editing and uploading photos. Then it was off to bed for an early start the next morning, with the trip over to Watarrka National Park and the Kings Canyon Resort.

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Visit the Red Centre Holiday 2016 web page at: