A University of Arkansas graduate student is taking a census of mosquitoes and the diseases they may carry in Arkansas. The Arkansas Department of Health is funding the survey that will be conducted this summer by Rebekah Crockett of Frederica, Del., who is working toward a master's degree in entomology. The study will be part of her thesis research.
“One of the big reasons behind the grant is the spread of West Nile virus,” Crockett said. “West Nile showed up in New York in 1999, spread by mosquitoes. Last year the virus was found in 12 states carried by 14 species of mosquito.
“The Department of Health wants to determine the potential for West Nile and other viruses borne by mosquitoes in Arkansas,” she said.
Besides West Nile virus, Crockett's survey will test for the viruses that cause St. Louis encephalitis and eastern equine encephalitis, mosquito-transmitted diseases that have occurred in Arkansas.
She will trap mosquitoes in six locations around Arkansas, near Fayetteville, Lonoke, Jonesboro, Pine Bluff, Dumas and West Helena. After identifying the species, she will separate them into samples and send them to a private lab in South Carolina that will perform genetic tests to look for the presence of viral RNA.
The collection sites were chosen based on past occurrences of mosquito-transmitted diseases or because they are in the flight path of migratory birds.
“Birds are known to carry diseases, like West Nile virus, from one area of the country to another,” Crockett said. “The viruses are transmitted from the birds to humans by mosquitoes.”
Max Meisch, UA Division of Agriculture entomologist, said there are about 55 species of mosquito in Arkansas, including the Asian tiger mosquito, a relative newcomer known to carry the virus that causes Dengue fever. It is believed to have entered the country inside tires shipped from Asia.
Meisch has helped develop and implement effective mosquito abatement programs for rice-growing areas through his Arkansas Agricultural Experiment Station research in mosquito bionomics and control using non-chemical approaches as well as conventional methods.
“The Asian tiger mosquito is a potential carrier of West Nile virus,” he said. “Laboratory tests show it to be one of the most efficient carriers of the virus, although it's probably much less efficient in transmitting the disease in the field.
“The Asian tiger mosquito only bites during the day, when birds are active,” he said. “And this mosquito is a generalist, feeding on the most convenient targets it encounters, so it lowers the ratio of direct transmission between birds and humans.”
Crockett will also be testing for pesticide resistance in Anopheles quadrimaculatus, known as the malaria mosquito, prevalent in rice-growing areas like eastern Arkansas.
Crockett received her bachelor's degree in entomology, with a concentration in wildlife conservation, at the University of Delaware. She worked two summers for the state of Delaware's mosquito control program.
Fred Miller is a science writer for the Arkansas Agricultural Experiment Station.