A Wooster Researcher Uses Mosquito Love to Fight Tropical Diseases

Feb 15, 2016

The Asian tiger mosquito is found across the southern U.S. and as far north as Ohio. While it's not the primary carrier of the Zika virus, it's believed it can transmit the disease.
Credit CDC

The Zika virus is rapidly spreading across South America, Central America, and the Caribbean.  It may soon spread to the U.S.  

It's carried by a mosquito native to Africa called Aedes aegypti, and by its cousin, Aedes albopictus, the Asian tiger mosquito, which has been found as far north as Ohio.

Scientists are amping up efforts to fight our oldest foes. One Wooster researcher thinks the key to controlling mosquitoes can be found by unlocking the secrets of their reproduction.

In this edition of Exploradio, we meet a mosquito 'love doctor' who studies the battle of the sexes on the molecular level.

The mating game
Laura Sirot teaches biology at the College of Wooster, but her passion is observing the intimate lives of insects: "I’ve spent a very good proportion of my life watching insects mate, I just find it so interesting.”  

Laura Sirot breeds mosquitoes at the College of Wooster in order to study their sex lives. She hopes to control disease-carrying insects by manipulating breeding behavior.
Credit COLLEGE OF WOOSTER

While mosquitos in the wild don’t need any extra motivation to get busy, she says in the lab, it’s important to set the mood.

The lighting, temperature, the humidity all have to be just right.  But music? Not an incentive. Apparently the vibrations bug mosquitoes.

Sirot uses a suction tube to place a single female into a cage filled with about 40 amorous males. And in about the time it takes to describe the encounter, it’s over.

“Mosquitoes actually mate face to face and they sort of form a v-shape with the tips of their abdomens and you watch them and time them and count to about 15-20 seconds and it’s likely that the female’s actually been inseminated.”

Male proteins affect female behavior
And that magic moment provides what she’s looking for, mosquito semen, now inside the female, which Sirot sadly places inside a freezer. 

It turns out that the seminal fluid of mosquitoes is packed with chemicals that change the behavior of females.

Laura Sirot in her College of Wooster lab. She's studying Aedes albopictus, the Asian Tiger mosquito, which carries dengue fever, Chickungunya and perhaps, Zika virus.
Credit COLLEGE OF WOOSTER

Sirot is working to identify those male mosquito proteins that, once inside the female, tell her to do things like ‘stop mating’ or ‘go get a sip of blood to help the eggs grow.’ 

She says scientists are trying to figure out is how males are able to influence female feeding and reproduction. "And if we can figure out how males are doing it, we’re hoping we can find new tools for us to do the same thing.”

Sirot and her colleagues are working to unravel the secrets of mosquitos’ sex life in order to develop control techniques that target only the harmful species and have little impact on the environment. 

Making sterile males more attractive
She says genetically modified male mosquitoes can be bred, with their seminal proteins signaling females to lay fewer eggs, or to mate only once --  a powerful tool when combined with another idea for controlling mosquitoes: releasing lab sterilized males into the wild.

She says if we can make those males raised n the lab more competitive, then we might be able to increase the effectiveness of the sterile male technique.
 

Credit CDC

Sirot’s work with the Asian tiger mosquito could help millions of people worldwide faced with dengue fever and other diseases carried by the pests. 

Asian tiger mosquitoes love discarded tires, and in the 1980’s eggs arrived in the Southern U.S. from used tires imported from Asia. They have found their way to Ohio, but so far the diseases they carry haven’t. 

Laura Sirot is a scientist on the front lines of pest control, but can’t suppress her admiration for insects’ love lives.

“These little beings have tiny little nervous systems and yet they have very highly complex behavior.”

Understanding that behavior and the chemicals that control it could be the next breakthrough in our continual battle against the mosquito menace.