Tuesday, December 14, 2010
Grand Exhibit Hall (Town and Country Hotel and Convention Center)
Most praying mantises detect ultrasound using a single ear in the ventral midline of the metathorax (HF system). At least nine mantis lineages have evolved a mesothoracic ear most sensitive to 2-4 kHz sounds (LF system). Extracellular recording in the CNS shows that both HF and LF information is distributed to the head and to the abdomen. The LF system is faster than the HF (ear to brain to caudal thorax in 28 ms vs. 36 ms). The two auditory systems are not completely independent. A preceding LF stimulus of moderate intensity reduces ascending HF auditory responses by 20-30%. However, the same stimulus parameters cause a 40-60% increase in HF activity descending from the head. Ultrasonic hearing protects mantises from bats, but the lower frequency range and the presence of LF (but not HF) hearing in nymphs suggests a different function for the mesothoracic ear.