Interesting study: Sleep-deprived mosquitoes are also 'lazy' to suck the blood of humans and animals

Sleep in humans is important for maintaining the immune system and restoring functions such as tissue repair and protein synthesis. Sleep has also been shown to be important for memory and brain function. On the other hand, lack of sleep can affect cognitive function and increase the risk of diseases.

Sleep is also important for mosquitoes.

In a recent study from the University of Cincinnati, researchers demonstrated the importance of sleep for mosquitoes. Research shows that mosquitoes disturbed the night before are more likely to spend the next day resting rather than looking for a host to feed on.

The study highlights how important the biological function of sleep is, even in insects.

Oluwaseun Ajayi, UC PhD student and lead author of the study, expressed surprise at the finding. Sleep is an evolutionarily conserved process in various animal systems, including insects. But sleeping in mosquitoes (the vectors of pathogens) has not been directly tested.

This is surprising because the well-studied circadian rhythms in mosquitoes are also governed by sleep. In addition, restorative sleep has been observed in other insects such as honey bees and fruit flies, as well as in humans.

Researchers from the University of Cincinnati's Department of Arts and Sciences and the Virginia Department of Biochemistry and Technology found it difficult to study sleep patterns in mosquitoes.

They spent more than a year developing efficient phenomena research procedures. Mosquitoes are very easily disturbed by the presence of observers because they see them as potential hosts. According to biologist Joshua Benoit, this means that any experiment on mosquito sleep is likely to be jammed in the presence of humans. "It's hard to quantify mosquito sleep as soon as you walk into the room," Benoit said.

Mosquitoes detect the presence of a potential host through body temperature, odors, movement, vibrations, and the CO2 that we exhale from our lungs and release from our skin. The researchers therefore had to keep the mosquitoes in rooms isolated from other rooms and use cameras and infrared sensors to record data without disturbing them. The team then used this video data to analyze the mosquito's behavior.

In this way, the scientists studied the sleeping and feeding behavior of three mosquito species for about a week. Between activities, mosquitoes will often spend a lot of time sitting on a surface to save energy and not easy to detect when they are actually sleeping.

However, scientists have identified a subtle postural change that occurs when mosquitoes sleep. 'When mosquitoes enter a sleep-like state, their hind legs droop and their bodies are closer to the surface,' Ajayi said.

Mosquitoes that are too tired from lack of sleep are also less likely to land on a host.

Using this knowledge, the researchers were able to determine from video how long the mosquito slept. The three species under investigation sleep at different times during the 24-hour cycle. Aedes aegypti sleeps mainly at night while Anopheles stephensi is most active at night, sleeping during the day. Culex pipiens, looking for a meal at dusk, sleeps during the day and at night.

In a second experiment, the researchers subjected sleep-deprived mosquitoes to activity for as long as they should have been asleep. They do this by vibrating the mosquito containers at regular intervals during that time.

While more than 75% of the mosquitoes that fly around actively seek out food if they are not sleep-deprived, less than a quarter of them are interested in foraging if they experience insomnia. This showed that the feeding propensity of the sleep-deprived mosquitoes was reduced by 54%.

Benoit said: 'It was surprising to me that mosquitoes need blood to produce eggs but they are willing to give it up just to restore lost sleep. They feel the need to suck blood because they need to sleep first'.

Mosquitoes that were overtired from lack of sleep were also less likely to land on hosts in both the laboratory and outside settings. Fatigue also impairs the ability to suck blood at times when mosquitoes are usually active.

According to the World Health Organization, mosquitoes cause more suffering to humans than any other animal. Malaria alone kills more than 400,000 people annually. Mosquitoes also carry many other deadly diseases such as dengue and yellow fever. By understanding mosquito circadian rhythms, researchers hope to find ways to prevent mosquito bites and the spread of disease.

The study was published in the Journal of Experimental Biology.