Broad versus narrow auditory tuning and corresponding bat-evasive flight behaviour in praying mantids

Most praying mantids possess a single tympanal ear located in the ventral m idline between the metathoracic legs. The auditory system is generally most sensitive to ultrasound in the 25-50 kHz range. Flying males exhibit a sho rt-latency, stereotyped, multi-component response to ultrasound that allows them to escape from attacking bats. This study describes a small subset of species that differs in three major respects from the majority of mantis s pecies: ii) their auditory tuning is 1.5-2 times broader; (2) they are sens itive to Frequencies above 60 kHz (up to 130 kHz in some species) with thre sholds as low or lower than at 25-50 kHz; (3) the behavioural response of t he broadly tuned (BT) species includes 10-50 times more flight cessations a nd can be far less stereotyped, i,e, more 'evitable', than that of narrowly tuned (NT) species. However, BT species do not differ from NT species in o verall sensitivity. Two species from one subfamily, the Amelinae (family Ma ntidae), stand out because they are among the least sensitive of any hearin g mantids so far tested. Although the two amelines differ from one another in tuning curve shape, they are both more broadly tuned than most mantids. The occurrence of BT species does not follow any obvious phylogenetic patte rn: they are patchily distributed among the mantis families, and both BT an d NT species can be found in the same subfamily or tribe. We suggest that B T species are responding to a shared ecological pressure. Based on their tu ning, the nature of their behavioural response, and their geographic distri bution, we hypothesize that high duty cycle (HDC) bars (Rhinolophidae and H ipposideridae) pose a special danger to BT mantids in addition to the threa t that all flying mantids face from the more common and widely distributed low duty cycle (LDC) bats.