Mosquitoes buzz off with birth con­trol

Weekend Herald - - Science & Tech - Dr Michelle Dick­in­son, cre­ator of Nanogirl, is a nan­otech­nol­o­gist who is pas­sion­ate about get­ting Ki­wis hooked on sci­ence and en­gi­neer­ing. Tweet her your sci­ence ques­tions @medick­in­son

Mosquitoes mak­ing you itch dur­ing the sum­mer bar­be­cue sea­son? Thanks to new sci­en­tific re­search, the fu­ture is start­ing to look bite-free — sci­en­tists have cre­ated a birth con­trol method for mosquitoes, de­signed to help erad­i­cate them with­out af­fect­ing the rest of the en­vi­ron­ment.

Af­ter hu­mans, mosquitoes are the most dan­ger­ous an­i­mal on the planet. Across the world, more than 500 mil­lion peo­ple are se­ri­ously af­fected each year by mos­quito bites — malaria, yel­low fever, chikun­gunya, Zika and dengue, for ex­am­ple, can all re­sult from just one bite and can be fa­tal.

Luck­ily, in New Zealand mosquitoes are just a nui­sance with their bites caus­ing noth­ing more than an itch — the re­sult of a re­ac­tion our bod­ies have to the mos­quito’s saliva that it in­jects while bit­ing.

To date, get­ting rid of mosquitoes has in­volved in­sec­ti­cides and pes­ti­cides, which are known to have a neg­a­tive ef­fect on the ecosys­tem. Some mosquitoes are be­com­ing re­sis­tant to these in­sec­ti­cides due to our long-term re­liance on chem­i­cal treat­ments, forc­ing sci­en­tists to come up with al­ter­na­tives. Re­searchers from the Univer­sity of Ari­zona de­cided to look at how the mos­quito was dif­fer­ent from other in­sects. Us­ing bioin­for­mat­ics, they searched for and iden­ti­fied genes that were unique to mosquitoes.

The func­tion of many of these genes was un­known, so us­ing a tech­nique known as RNA In­ter­fer­ence they turned off each of these genes in­di­vid­u­ally, us­ing small RNA mol­e­cules to try to see what the ef­fect of the change was on the mos­quito. Of the 40 mos­quito-spe­cific genes they tested and turned off, one seemed to be re­spon­si­ble for the struc­ture of the eggs that the fe­male mosquitoes laid.

When the sci­en­tists blocked this pro­tein, which they called Eggshell Or­gan­is­ing Fac­tor or EOF-1, the fe­male mosquitoes laid eggs with de­fec­tive shells, caus­ing the nor­mally dark eggshells to be pale and por­ous.

This de­fect caused many of the eggs to col­lapse, and the embryos in­side the eggs to die. The ef­fect was long-term and once the gene treat­ment had been given to a mos­quito all of her eggs were de­fec­tive for the rest of her 50-day life. Al­though the fe­male mos­quito would con­tinue to bite she was not able to re­pro­duce, thus re­duc­ing the over­all num­ber of mosquitoes in an area over only a few months.

The re­search pub­lished in the jour­nal PLOS Bi­ol­ogy showed that the treat­ment — be­cause it was mos­quito-spe­cific — could po­ten­tially be ap­plied to large ar­eas known to har­bour in­fected mosquitoes with­out af­fect­ing other or­gan­isms nearby.

Al­though the com­plete erad­i­ca­tion of the mos­quito species sounds tempt­ing, as nec­tar eaters they are still great pol­li­na­tors for plants and pro­vide a food source to birds and fish. The end goal would be to re­duce the mos­quito pop­u­la­tion sig­nif­i­cantly enough to break the cy­cle of dis­ease trans­mis­sion be­tween mosquitoes and hu­mans in high-risk ar­eas rather than get rid of them com­pletely.

In the mean­time, while we wait for this new birth con­trol to be com­mer­cialised, the best way to get rid of mosquitoes in your back gar­den is to check for and re­move any stand­ing wa­ter.

Mosquitoes breed in stand­ing wa­ter, so re­mov­ing small pud­dles that may have ac­cu­mu­lated in flower pots or other gar­den con­tain­ers gives them fewer places to breed mean­ing fewer mosquitoes in your gar­den at least.

An­other easy trick, if it’s not windy, is to add some stand­ing fans to your out­door area. Mosquitoes may be good biters, but they aren’t great fly­ers — and strug­gle to fly in fast­mov­ing air, so by blow­ing a breeze over your out­door gath­er­ing area you not only keep peo­ple cool but also bite free as well.

Pho­tos / Getty Im­ages; File

With birth con­trol, sci­en­tists hope to re­duce the mos­quito pop­u­la­tion enough to break the cy­cle of deadly dis­ease trans­mis­sion.

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