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NMSU biology professor seeks effective method to eliminate mosquito-transmitted diseases

Mosquito-transmitted diseases like malaria, Dengue Fever and West Nile virus sicken and kill millions of people every year. Due to the lack of effective vaccines and an increase in insecticide-resistant mosquitoes, the threat of these diseases continues to grow.

Immo Hansen, New Mexico State University assistant professor of biology, holds a paper covered in thousands of yellow fever mosquito eggs. Students in Hansen's lab are examining the mosquito species in hopes of finding effective ways to prevent and eliminate the spread of mosquito-transmitted diseases, like Dengue Fever. (NMSU photo by Donyelle Kesler)

About 100 million people worldwide are affected each year by Dengue Fever along with several hundred thousand more cases with the more severe form -- Dengue Hemorrhagic Fever transmitted by the yellow fever mosquito.

Immo Hansen, an assistant professor of biology at New Mexico State University and the Institute of Applied Biosciences and Molecular Biology Program, and his team of undergraduate and graduate student researchers are studying the yellow fever mosquito. They are working on two different approaches to effectively prevent and ultimately eliminate mosquito-transmitted diseases spread by this type of mosquito. Originally brought over from tropical Africa during the slave-trade era, the yellow fever mosquito can be found in the southern states of the U.S.

"These mosquitoes transmit very dangerous diseases," Hansen said. "In the Molecular Vector Physiology Laboratory, we study the molecular biology of these mosquitoes. We are very interested on how they use the nutrients they take from our blood and how they shuttle them in their body."

The yellow fever mosquitoes can live on nectar and sugar-water alone. It is when they want to produce eggs that they require protein found in blood. By understanding the molecular biology of these mosquitoes, the group aims to create more effective insecticides to kill the mosquitoes and produce sterile males to cut down their population.

"The world is in dire need of new insecticides as the old ones become more and more ineffective because of resistance," Hansen said. "We are also working on another strategy to reduce mosquito populations that is pesticide free. The sterile insect technique works by releasing millions of sterile male insects into the wild. The yellow fever mosquito effectively mates only once. So if a sterile male mates with a female, she will not produce eggs. By releasing sterile males on a regular basis you can bring down populations completely. This has worked with several different species of insects."

Hansen's lab team consists of two graduate and four undergraduate students, each working on a different aspect of the physiology of the mosquito.

Ideally, sterile male mosquitoes should outcompete and outlive the mosquito males found in the wild. For that reason, students are researching the nutrition and energy storage of these insects. Senior Alyson Banegas has been working in the lab for two years, working with the gene "lipid storage droplet protein two" that regulates fat accumulation in mosquitoes. Her research will help the team understand how the lack of fat in mosquitoes effects development and reproduction.

Senior Sarah Aguirre is working to creating a transgenic mosquito line. By using molecular biology techniques, Aguirre wants to manipulate the nutrient accumulation in the larval stage of the mosquito.

"If we can manipulate nutritional signaling, we can create stronger sterile males that will better compete with the wild type males," Aguirre said.

Recent graduate Victoria Carpenter is working as a technician in the laboratory before attending graduate school at Duke University in the fall. She studies cationic amino transporters found in the fat tissue of the mosquito. By manipulating these transporters, Carpenter is looking to see how this affects reproduction.

Stacy Rodriguez, a graduate student, raises different mosquito strains under different nutritional regimens to create small and large mosquitoes. The smaller mosquitoes represent the size of the mosquitoes that are found in the wild. Through a series of cross experiments, she will be able to determine the optimal mosquito size for the sterile insect technique.

Ph.D student David Price, in addition to his many tasks in the lab, is doing bioinformatics work. He is documenting the differences in gene expressions and metabolites in mosquitoes raised under different nutritional and crowding conditions, before and after they take blood. Using a pyrosequencer that can read millions of bases of DNA or RNA, the team can see the differences in the types of RNA, one of the three major macromolecules (along with DNA and proteins) that are essential for all known forms of life, between mosquitoes exposed to the different conditions.

Yellow fever mosquitoes are native to the Las Cruces area and the team has established a Las Cruces strain in the laboratory. This strain has been tested by NMSU Biology professor Kathryn Hanley who found that it can carry Dengue Fever and therefore has the potential to become a problem. However, Hansen says that while mosquitoes in the area do pose a threat, there are ways to protect yourself.

Hansen suggests wearing long sleeves and pants in the evenings when outdoors and using mosquito repellents like DEET. Most importantly, get rid of any stagnant water in the yard where mosquitoes can breed. Homeowners may want to purchase Gambusia and other mosquito fish from local pet stores for their ponds.