WIKIMEDIA COMMONS | The biology department invited Tovi Lehmann, a facility head at the Laboratory of Malaria and Vector Research at the National Institute of Allergy and Infectious Diseases, to speak about mosquito survival at high altitudes on Sept. 19 as part of their seminar series.
Tovi Lehmann, facility head at the Laboratory of Malaria and Vector Research at the National Institute of Allergy and Infectious Diseases, spoke to students and faculty Sept. 19 about new findings regarding mosquitoes’ abilities to survive and thrive at high altitudes, discussing implications for efforts to combat vector-borne diseases in Africa.
This presentation was part of the biology department’s seminar series, which invites scholars in biology to share their research and engage with Georgetown University community members.
Peter Armbruster, Davis Family distinguished professor in the biology department, hosted the event. He highlighted that Lehmann’s research addresses crucial questions concerning the dry season ecology of malaria vectors in semiarid regions of Africa.
“This is research that was not going very far until Tovi started working on it and essentially cracked the problem wide open,” Armbruster said at the event.
Lehmann began by outlining his lab’s research process. At sunrise, strategically placed aerial nets are launched and then later retrieved at sunset. These nets are equipped with control panels to ensure only high-altitude mosquitoes are collected.
Once captured, individual mosquitoes are carefully extracted and preserved in RNAlater, a solution that permeates tissue samples and stabilizes RNA. This preservation method, combined with the isolation of the abdominal cavity, allows researchers to identify pathogens present in the insect’s most recent blood meal, according to Lehmann. To determine the species of mosquito harboring the virus, Lehman also said researchers sequence its mitochondrial DNA.
The lab also employs other techniques such as Sanger sequencing and metagenomics. While Sanger sequencing is an established method of reading small sequences of the genome, the practice of metagenomics is a recent advance in microbial ecology that analyzes all genomes within a communal environmental sample.
Lehmann emphasized that while data collection in this field can be a time and labor-intensive process, the results are invaluable to their research.
“The samples are not huge. It’s not like we are collecting tens of thousands of mosquitoes,” Lehmann said. “We are amassing a few thousand after a year or year and a half.”
Previous research has focused primarily on the Sahel, a hot semiarid climate zone stretching across the southernmost latitudes of North Africa. The Sahel is a transient resource habitat that selects for species capable of easy migration and dispersal. However, Lehmann noted that his group collected data from other, more stable ecozones of western Africa, such as Ghana’s equatorial forest.
If mosquitoes are found in high altitudes in these areas, it suggests that mosquitoes in many ecozones, not just unstable ones, can catch winds and travel much further than those that stay low to the ground. The trait describing a mosquito’s ability to migrate at these high altitudes is called high-altitude dispersion. Combined with windborne movement, which Lehmann identified as a significant component of migration, this trait can pose challenges for vector-borne disease control.
Lehmann said his group found that high-altitude dispersion is a widespread behavior among the 60 mosquito species they studied.
“This is not a rare behavior that only one or two mosquito species have taken advantage of,” Lehmann said. “It’s very mosquito-ish to engage in high altitude-dispersion.”
Lehmann then addressed the potential human impacts of these findings. If malaria-carrying mosquitoes can migrate at high altitudes and travel great distances, their habitat ranges may shift and could significantly expand. This expansion may expose previously unaffected communities, particularly urban areas, to malaria risks. These newly affected regions may face a steep learning curve in handling new malaria cases.
“Nearly half of the total continent population typically benefits from very low malaria exposure,” Lehmann said. “Therefore, immunologically, they are much more susceptible to more severe forms of the disease.”
Lehmann concluded his presentation with a call to action, emphasizing two key strategies: tracking emerging threats and preventing reintroduction. He stressed the importance of intercepting mosquito species relocation before they have the chance to adapt to their new environments. Additionally, Lehmann advocated for swift and decisive responses to potential outbreaks, even if initial measures are imperfect.
“Many of these invasive species can turn out to be extremely consequential for human pain, human life and economic value. I cannot imagine why we are not seizing this time,” Lehmann said.
Lehmann cautioned that delaying action while awaiting further research could lead to the uncontrolled spread of urban malaria across Africa. He emphasized that his lab’s findings indicate that scientists must act quickly.
“They are not doing it alone,” Lehmann said in reference to the movements of high-altitude mosquitoes. “Their pathogens are likely to be benefiting from these travels.”