D.N. LAPSHIN, D.D. VORONTSOV

TEMPORAL DYNAMICS OF HOST-LANDING RATE IN MOSQUITOES ATTACKING THE IMITATION OF A HOST

The rates of mosquito landing on a host-imitating device were measured. The device contained an electric heater to imitate the presence of a warm-blooded animal, a gauze screen impregnated with meat juice, a microphone with an amplifier to record the sounds of mosquito landings and take-offs, and a light meter to record the ambient illumination. In addition, the behavior of mosquitoes near the device was studied by video recording. All the experiments were conducted in the first half of June in evening and morning hours in mixed spruce-birch forests of Moscow region. Audio recordings were digitally analyzed to estimate the landing rates. Significant (more than 50% of the average) quasi-periodic fluctuations of the mosquito landing rate were revealed. The peaks of mosquito activity alternated with drops with an average period of 30 min (20-50 min in different recording sessions). These fluctuations were recorded in calm weather during a gradual change in illumination. Experiments with two similar devices positioned 20 m apart showed that fluctuations of mosquito activity developed independently at each site. The fluctuations in the mosquito landing rate seem to be largely determined by endogenous factors: mosquito females, failing to obtain blood from the host-imitating device, lost interest in it and landed to rest on the nearby vegetation. After 20-50 min, the memory trace of the previous experience gradually faded, and mosquitoes returned to the attracting device thus starting the next peak of activity.