A new study being conducted by the Mosquito Research and Control Unit is targeting mosquitoes that feed on blue iguanas. The research project, which began in April this year, is a joint effort between the MRCU and Mississippi State University.
“Our interest is determining what species of mosquitoes feed on the blue iguanas,” said MRCU Director James McNelly.
At the core of the research is a hypothesis that invasive green iguanas could be a potential source of viruses and diseases, which could be transmitted from the greens to the blues via mosquitoes.
The project is divided into two stages. First, field officers and scientists venture out to the Blue Iguana Recovery Program site at the Queen Elizabeth II Botanic Park in North Side. Once there, specialised mosquito traps are placed under wire cages of juvenile blue iguanas.
“Blood-fed mosquitoes are not able to fly far,” said Dr. Hamady Dieng, an MRCU research scientist. “By placing the traps under the cages, we make it more attractive for mosquitoes that have fed on blue iguanas. Because it is so hot, we try to make the traps humid and moist, which also helps to attract the mosquitoes.”
The traps are checked regularly, and the mosquitoes collected are taken back to the MRCU labs for the second phase of the project.
Once in the lab, staff dissect the mosquitoes that have taken a blood meal. Samples are recorded and are then shipped to Mississippi State University for further analysis.
Preliminary findings reveal the two types of mosquitoes most frequently found in the traps are both from the Culex species.
Mark Welch, an MSU biology professor who is helping to oversee the project, said although it’s been six months since the research began, it is still too early to tell whether the mosquitoes have fed on humans or iguanas, as well as which type of iguana.
“We are in a stage before the fact-finding stage,” said Welch. “I have never worked with mosquitoes before. I have worked with iguanas. My speciality is in the genetics of iguanas, so we are going to have to learn how to isolate iguana DNA from a mosquito blood meal.”
For Welch and his team, the immediate problem they must solve is how to get an adequate blood sample that can be used to find distinct genetic markers of either blue or green iguanas.
“I know it seems like a lot when I get bitten, but that’s not a huge sample to work with in a genetics lab,” said Welch. “We are going to have to develop a protocol that will allow us to use genetic material from the blood meal to identify the species of [the] host that provided that meal. But once we are there, then it should be downhill.”
The project also faces several other problems. In the field, the traps must compete with lush foliage that surrounds cages of blue iguanas, which decreases the number of mosquitoes that enter the traps. The number of mosquitoes that do eventually make it into the traps is further reduced by predators lying in wait.
“Spiders have learned to prey on blood-fed mosquitoes, so we are finding more and more traps with no mosquitoes, but containing multiple spiders,” said Dieng.
To help counter the arachnid intruders, the MRCU deployed new dustbin traps. In one dustbin trap, some 15 mosquitoes were recovered.
Another issue facing the scientists is transferring the samples in a manner that allows them to remain viable once they have arrived at MSU.
By the end of the one-year test phase, the MRCU team hopes it will have been able to collect, dissect and analyse the blood samples – and ultimately determine what host provided the sample.
“One of the goals is to ultimately be able to do all the work here on island,” said Welch.
The cost of the project is unclear, but it is understood that the MRCU will be footing the bill.
“This is part of our mission. We are Mosquito Research and Control, and this is the leading edge of looking of what [mosquitoes] feed on,” said McNelly. “This particular programme is all about iguanas, but we expect to look at other mosquitoes and what they feed on. For instance, Aedes aegypti and what that mosquito feeds on.”
McNelly said eventually the programme could be expanded to other animals.
“I wouldn’t be surprised if we expand the focus of what we are talking about here and finding some mosquitoes that actually have fed on chickens,” he said. “But it wouldn’t be a programme specifically looking at mosquitoes that feed on chickens.”