SEXUAL SIGNALLING IN BLADDER GRASSHOPPERS: TACTICAL DESIGN FOR MAXIMIZING CALLING RANGE

摘要: Pair formation in the bladder grasshopper (Bullacris membracioides) is by duetting and male phonotaxis. Lowfrequency stridulatory signals are emitted an abdominal resonator answered females using a species-specific time delay. Acoustic transmission natural environment was studied playback of sexual over distances 450 m under two atmospheric conditions (day night). Upward-refracting sound shadow zone beyond approximately 50 prevailed during day. enhancement demonstrated at night when downward-refracting temperature inversions created tunnel effect with caught between ground zones different temperatures. Transmission almost ideal species actually calls; calling 150 for signal afternoon increased to 1.5‐1.9 km night, arguably largest distance yet reported insects. In contrast, female calls transmit maximum m, signifying marked discrepancy active space sex-specific signals. may, however, be profoundly affected levels masking noise. Adaptations increase range may variously found itself, behaviour patterns or sensory system. Here we demonstrate aspects first types adaptation signalling system which maximizing appears major selection pressure, lesser effects imposed inter- intraspecific pressures channel. Summary