Malaria mosquitos apply an ingenious technique to get away from their victims very quickly and very quietly. This technique involves beating their wings extra fast just before take-off while steadily increasing the pressure in their long legs. This is the finding of research conducted by Wageningen University & Research and the University of California, Berkeley (USA), published in the Journal of Experimental Biology.
It is vitally important to mosquitos that they are not discovered by their victim while they are feeding. Knowledge of how they manage to escape unnoticed can be used in the fight against these disease-transmitting insects.
Female mosquitos need blood for their eggs to develop. Unfortunately, however, they also transmit dangerous diseases such as malaria while feeding on their victims. Knowledge of how these mosquitos get away can help combat such diseases. To investigate how a mosquito ‘heavy’ with blood gets away unnoticed, the researchers used high-speed cameras to record in minute detail how the mosquito takes off. The researchers knew that most insects simply push off hard on their legs to launch themselves in the air. They were therefore surprised to find that, just before take-off (30 milliseconds), mosquitos start to beat their wings at an exceptionally high frequency of 600 beats per second (as similar insects beat their wings at ~200 beats per second). As a result, the wings supply 60% of the force required to take off. Mosquitos also use their long legs to gently increase the pressure in these 30 ms, so that the victim is completely unaware of the insect’s take-off.
The research team then compared the mosquito’s take-off with that of the fruit fly, to see whether the technique has any effect on the time it takes to get away. The fruit flies turned out to apply four times as much force to take off, which is enough to be noticed by a human. However, when the team compared the speed of the insects, the mosquitos were just as fast as their less subtle competitors, which means that their gentle take-off technique goes unpunished.
The researchers would like to carry out further research to see whether other blood-sucking insects use the same strategy to outwit their victims. The team is also interested to find out whether the insects’ landing is just as graceful as their take-off. This study is part of a larger project in which fundamental knowledge is applied to combat mosquito-borne diseases such as malaria, for example by making better mosquito traps.