Killer fish to save Shanghai from mozzie plague

There's a few things in this life that start with the letter M that Shanghaiist doesn't like. Malingerers, marmite, and men with no moustache but full beards (OK, the last one is a bit of a stretch M-wise). Some would say that these are irrational and ill-conceived categorisations, but there is another one on the list that isn't — and that is mosquitoes. And it looks like Shanghaiist isn't going to enjoy our coming summer evenings.

We report that the Shanghai Daily reports on a story featured in the Shanghai Morning Post that one of the downsides of our recent mild winter is the news that Shanghai's resident mosquito population had a few more additions following Chinese New Year and we might have to battle up to twice the usual numbers of mosquitos this coming July.

The pests (mosquitoes) have been found in ponds in construction sites, in wet markets and in underground parking lots this month, according to a study of 100 locations being monitored in the city.

"However, these larvae were seldom seen in previous Februaries because they had lower temperatures and less rain," Jin Peiwu, vice director with the Shanghai Patriotic Health Campaign Committee, told the Shanghai Morning Post yesterday.

But in their infinite and unyielding wisdom, the Shanghai Patriotic Health Campaign Committee have proffered a potential solution to our upcoming mosquito ills — send in the mosquito killing fish!

The committee plans to raise Gambusia, a killer-fish that feeds on the insect's larvae, in local sight-seeing fountains and in streams from next month.

Insecticides are no longer recommended because of the mosquito's growing resistance to the drugs in them, Jin said. "It's also in consideration of the environment. But of course, the best way to destroy them is to keep dry and clean everywhere," he added.

Apart from the reasonable and well-established advice of getting rid of stagnant water sources, Shanghaiist has some reservations regarding introducing Gambusia to Shanghai's local freshwater environments.

Members of the Gambusia genus are also commonly known as 'Mosquito Fish'. It is reputedly one of the best natural predators of mosquitoes. However, there is a lot of evidence that Gambusia don't actually counter this problem, but figuratively speaking, they just open up another can of worms in water ecosystems. In contrast to this evidence, there's also reported positive applications of this fish as a mosquito bio-control agent in various North American states. So who do you want to believe?

As this little Shanghaiist is an Australian and also an environmental scientist, we are quite wary of introducing foreign species as agents of biocontrol. But other places aren't, and hey, this is China — anything can and does happen with regard to environmental issues here.

One immediate potential problem that springs to mind is the ability of Gambusia to out-compete and displace native fish. Pose this scenario; our saviour killer-fish jump from highly controlled systems like Shanghai's streams and public fountains¡, and then into the wider local environment, or perhaps into aquaculture industries located in the Shanghai/Jiangsu region. Goodness knows what about the long-term effect could be for the pond anglers in People's Square?

Don't get us wrong. We're all for safe, proven biocontrol strategies, but preferably using species native to the region you live in.

Nonetheless, we have no doubt that despite the measures put in place by the Shanghai Patriotic Health Campaign Committee, we are sure that we will be spending our summer with our apartment windows firmly closed, RID and Aerogard applied to our skin, and to the chagrin of our loved one, following our ritual, nightly stalking campaign to rid our bedroom of the rogue Anopheles, Culex or Aedes bitey that somehow crept into our impenetrable nocturnal fortress.

And yes, we should have got that apartment above the 10th floor just for this reason.

Photo taken from The People's Daily.