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Scared of sharks and alligators? Maybe you should be worried about something much smaller that kills more people than any creepy fish or reptile.
That deadly creature is the mosquito.
Despite its tiny size, this disease-carrying vector is responsible for spreading dreaded pathogens that cause illnesses throughout the world, like malaria, West Nile, dengue fever, dog heartworm, chikungunya and the latest newsmaker Zika virus. There are nearly 3,500 different species of mosquitoes and some are so small, you can barely see them. While others are as large as quarters.
They don’t have huge teeth. Their weapon of destruction is a minuscule proboscis that probes into the skin to draw blood. The saliva left behind can carry pathogens for terrible diseases, some of which have killed millions, thus making the mosquito the most important insect in terms of the medical costs to humans and animals worldwide.
Uncovering ways to control the deadly mosquito has become a passion for Dr. John R. Wallace, medical and forensic entomologist and professor of biology at Millersville University.
Wallace has been involved in research relating to population dynamics and feeding ecology of immature and adult mosquitoes nearly 25 years. He has managed surveillance of mosquito populations in Lancaster County, as well as research the role of storm water management regarding outbreaks of West Nile virus, another mosquito-borne illness that came from the Middle East.
Zika, of course, is in the news with as the 2016 Summer Olympics comes to Rio de Janeiro in Brazil this July. Zika typically causes fever, rash, joint pain and red eyes. What is creating a worldwide scare is the possibility that babies being born with microcephaly— or abnormally small heads and brains— may be linked to Zika virus.
“The Zika virus has been around since at least mid/late 1940’s,” says Wallace. “The jury is still out on what is causing these birth defects though strong correlational evidence supports the contention that Zika does lead to these anomalies.”
There has been speculation that the measures taken to eradicate mosquitoes, such as spraying insecticides might also play a role. Until more is known, worldwide precautions are being taken for women who are pregnant, or trying to get pregnant, in countries where the Zika virus has occurred.
In the meantime, at Millersville, Wallace and his biology students are hard at work on finding ways to reduce mosquito populations and reduce the risk of dreaded mosquito-borne illnesses like Zika. Wallace reports that Guillain-Barre syndrome and other types of encephalitis are of great concern as well.
There are mainly two mosquito species of concern in the transmission of the Zika virus, reports Wallace. The main culprit is the Aedes aegypti, also called the yellow fever mosquito. The other up-and-coming potential Zika spreader is the Aedes albopitus, known as the Asian tiger mosquito. Aedes aegypti are usually found in South America, the Caribbean, Asia, Africa and other tropical regions, although it is moving north to Florida, Mexico and other locales. The Aedes albopitus is even more worrisome, since it is already here. If you have ever seen a particularly attractive mosquito with black and white stripes, that’s probably the Asian tiger mosquito.
At Millersville, Wallace and students like senior Kayli Thomas, ’17, are hard at work rearing mosquitoes that will be used in a study of a new product being developed by a Lancaster area company. The Aedes aegypti larvae will be allowed to grow into adult mosquitos. The study focuses on the adult females, which are the carriers of the virus. The device is meant to resemble tree stump holes— a favorite mosquito hangout for laying eggs— luring the females into the trap from which they become ensnared. Wallace is intrigued by the concept, which does not involve insecticides that have their own ecological risks.
“I have been carefully raising and feeding these little mosquito larvae, known as wigglers, so I feel very invested in their care. It will be interesting to see what happens with the traps, to see how well they work,” says Thomas, who hopes to work in environmental conservation after she graduates.
Thomas is not the only Millersville student to make impressive strides in mosquito control. Joe Receveur, ’16, did his research on the bactericidal effects of larval mosquito habitat and gut mircobiomes following Hurricane Sandy in New Jersey. Would standing water and felled trees that harbored mosquitos increase mosquito populations?
Ryan Walker, ’16, also worked in New Jersey, developing a dichotomous key for larval mosquito identification for the Hunterdon County Department of Public Health West Nile Control Program. Calen Wylie, ’15, researched the effects of Ailanthus altissima plant extract from the Tree of Heaven on target adult mosquito control.
Wallace has worked on extensive research on the dynamics and food web relationship of mosquito larvae and other macro invertebrates in relation to the possible transmission of Mycobacterium ulcerans, the causative agent in the truly dreadful flesh-eating Buruli Ulcer, a necrotic skin disease that affects people in West Africa, Australia and South America.
“At first, it did not seem that there was a connection between mosquitos and the bacteria that cause Buruli Ulcer. But then it became apparent that there may be a rather atypical mode of transmission,” says Wallace.
That all goes to show that mosquitos really are pretty nasty creatures. Thanks to ongoing research at Millersville University, it may just be possible to at least slow down these tiny disease-carrying monsters.
