LOS ANGELES: Mosquitoes are more likely to feed on cattle than on humans if they carry a specific chromosomal rearrangement in their genome, reducing their odds of transmitting the malaria parasite, a new study has found.
Rates of malaria transmission depend on whether mosquitoes bite humans or animals, and whether they rest after that meal in an area where they will encounter pesticides.
Bradley Main from University of California’s Davis School of Veterinary Medicine in the US and colleagues investigated whether there is a genetic basis to host choice and resting behaviour in Anopheles arabiensis.
That species of mosquito has become the primary vector of malaria in east Africa due to its broader host range and the frequent use of pesticide-treated bed nets, which kill other species that live closely with humans.
“Whether there is a genetic basis to feeding preferences in mosquitoes has long been debated,” Main said.
“Using a population genomics approach, we have established an association between human feeding and a specific chromosomal rearrangement in the major east African malaria vector.
“This work paves the way for identifying specific genes that affect this critically important trait,” added Main.
Using genetics to better understand and track mosquito behaviour can improve local control strategies. This knowledge may also open novel avenues for stopping malaria’s spread, such as genetically modifying mosquitoes to prefer cattle over people.
The researchers sequenced the genomes of 23 human-fed and 25 cattle-fed mosquitoes collected indoors and outdoors from the Kilobero Valley in Tanzania.
They identified a genetic component that contributes to the mosquito’s host choice but not its choice of resting place.
They narrowed down the gene region associated with cattle feeding to a chromosomal rearrangement called the 3Ra inversion.
The study is the first to use genomic tools to find a genetic basis for earlier observations that inversions can be linked to a preference for cattle in mosquitoes.
The study appears in the journal PLOS Genetics. (PTI)
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