D.N. LAPSHIN, D.D. VORONTSOV

RETRANSMISSION OF ECHO-LIKE SIGNALS: METHOD END RESULTS OF STUDIES ON NOCTURNAL MOTHS (INSECTA)

Studies of capability to echolocate in nocturnal moths using the method of echo-signal retransmission are described in detail. During retransmission the insect is presented not with the echo from some real object but with electronically generated echo-like signal which appears following the certain delay after the insect's own acoustic signal. In that way the artificial echo from non-existent obstacle is produced. In the current work the delay was set to 0.5 ms that corresponds to a distance of about 8 cm from an obstacle. At the same time a single movement of any object does not take place near the flying insect therefore the activities of sensory systems other than auditory do not cause systematical influence on results obtained. Noctuid moths (Noctuidae, Lepidoptera) are acoustically active insects. They are capable of producing ultrasonic clicks during flight. The most typical response of a moth to the retransmision of echo-like stimuli is an activation of own clicks emission that is often accompanied with a rise in click amplitude. Using the activation of emission as a criterion of moth's response to the echo-like stimulation we measured echolocational thresholds in three species: Amphipyra pyramidea (36 dB SPL), Enargia paleacea (31 dB SPL) и Blepharita satura (26 dB SPL). The ability to echolocate was also demonstrated in 20 species of subfamilies Noctuinae, Hadeninae, Amphipyrinae, Cuculliinae, Catocalinae, Heliothinae.