A new study has upended the traditional belief that only female mosquitoes suck blood and transmit diseases. This discovery suggests that male mosquitoes are not completely harmless as previously thought and may play a small role in disease transmission.
Under certain conditions, male mosquitoes can also seek out blood sources as a survival strategy.
Scientists have found that male mosquitoes from the species Culex tarsalis and Aedes aegypti—species that typically show little interest in blood—will attempt to feed on blood when humidity is low and they are unable to access their usual nectar sources.
Male mosquitoes may seek blood as a survival strategy. (Photo credit: realestate.com.au).
This finding originated from an accidental observation by a graduate student in the laboratory of Professor of Entomology Jason Rasgon at Penn State University. They noticed that some male mosquitoes occasionally sucked blood through a thin artificial membrane when researchers lowered humidity levels and deprived them of their usual nectar food source.
To test whether male mosquitoes could suck blood directly from humans, Professor Rasgon conducted a bold experiment by placing his hand inside a mosquito cage. While male mosquitoes provided with enough water showed little reaction, those that were dehydrated landed on his skin and began probing. One even attempted to bite, although it only penetrated the outer layer of skin.
However, the structure of the male mosquito’s proboscis does not allow them to penetrate deeply to suck blood like female mosquitoes can. Nonetheless, through a scratch made by a cat, Rasgon discovered that dehydrated male mosquitoes could extract blood from an open wound.
In another experiment, scientists found that genetically modified male Aedes aegypti mosquitoes, which could not sense humidity, did not tend to suck blood more frequently when humidity was low. This suggests that male mosquitoes may seek blood to quench their thirst.
Previously, scientists believed that blood was toxic to male Culex quinquefasciatus mosquitoes and that male mosquitoes, in general, were unable to digest blood. However, in Rasgon’s experiment, male C. tarsalis that fed on blood not only survived but lived slightly longer than those that did not feed on blood.
While Professor Rasgon does not believe that male mosquitoes play a significant role in disease transmission, this discovery forces the scientific community to re-evaluate the notion that male mosquitoes do not suck blood. Further research is needed to determine whether, in rare cases, male mosquitoes can transmit viruses.
This discovery is particularly noteworthy because both mosquito species in the study are vectors for dangerous diseases. Aedes aegypti is a primary agent of yellow fever and can transmit diseases such as Zika, chikungunya, and dengue fever, while female C. tarsalis mosquitoes can transmit West Nile virus and St. Louis encephalitis.
