Abstract:
Ultrasound is detected by the female Anopheles gambiae using its antenna, evoking either an attractive or
repulsive response. Electronic mosquito repellents which exploit this concept in attempt to control malaria, have shown only
20 % effectiveness in repellence. The 112 Avisoft and 702 digital recorders were used to record sounds of Coleura afra and
Amolops tormotus respectively. The sound of C. afra and A. tormotus were recorded, combined and filtered using the Avisoft
software. The startling effect of the combined sound on female A. gambiae and the frequency range of optimum startle
response were determined in this study. A bioassay was set up with 3-4 day old female A. gambiae exposed to 10-34 kHz,
35-60 kHz and 61-90 kHz frequencies of combined sound, total activities and behavioural responses observed and noted. The
female A. gambiae were significantly startled by the 10-34 kHz combined predator sound triggering evasive behavioural
responses in 30 % of the mosquitoes. An antenna erection of 58.5𝑜𝑜 besides secondary effects like physical injury, unusual
rest and movement, fatigue and falls; attributed to stress on the nervous system and fear of predation was observed. The
combined ultrasound effectively repels the female A. gambiae.
