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Earlier studies of phonotaxis by female crickets describe this selective behavioural response as being important in the females' choices of conspecific males, leading to reproduction. In the present study, moderate (30+) to very large data sets of phonotactic behaviour by female Acheta domesticus L., Gryllus bimaculatus DeGeer, Gryllus pennsylvanicus Burmeister and Gryllus veletis Alexander demonstrate substantially greater plasticity in the behavioural choices, as made by females of each species, for the syllable periods (SP) of model calling songs (CS) than has been previously described. Phonotactic choices by each species range from the very selective (i.e. responding to only one or two SPs) to very unselective (i.e. responding to all SPs presented). Some females that do not respond to all SPs prefer a range that includes either the longest or shortest SP tested, which fall outside the range of SPs produced by conspecific males. Old female A. domesticus and G. pennsylvanicus are more likely to be unselective for SPs than are young females. Each species includes females that do not respond to a particular SP when responding to CSs with longer and shorter SPs. The results suggest that the plasticity of phonotactic behaviour collectively exhibited by the females of each species does not ensure that choices of a male's CS effectively focus the female's phonotactic responses on CSs that represent the conspecific male. The phonotactic behaviour collectively exhibited by females of each species does not readily fit any of the models for selective processing by central auditory neurones that have been proposed to underlie phonotactic choice.

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1. Inactivating one L 1 results in angular errors and circling during orientation toward the side having the intact L1 in response to calling songs (CSs) whose intensities are below the threshold for L3 (Figs. 2, 3A). When song intensities are increased above the threshold of L3, circling decreases (Fig. 3B).2. Following inactivation of one L1 and occlusion of the ear providing input to the intact L1, no phonotaxis occurs in response to CSs at 60 dB (below the threshold of L3; Fig. 4A) demonstrating the necessity of L1 for phonotaxis. Orientation, at large and consistent angular errors (Fig. 5A) and circling (Fig. 5B) to the unoccluded side resumes when song intensities are increased above the threshold of L3 (Fig. 4B) suggesting that a single L3 can induce phonotactic responses.3. Inactivation of one L3 causes angular errors in orientation when CSs are above its threshold (Figs. 6A, 7), which are not apparent when CSs are below L3's threshold (Figs. 6B, 7).4. Inactivation of one L3 and occlusion of the ear providing input to the contralateral L1 and L3, leave only one L1 functioning. This results in turning and circling toward the unoccluded side containing the one functioning L1 (Figs. 6C, 8), thus confirming the sufficiency of L 1 for phonotaxis.

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