Female preference for symmetric calls in a grasshopper

Grasshoppers produce calls by alternating use of a row of pegs on the two h ind legs. The number of pegs per row in the grasshopper Myrmeleotettix Macu latus demonstrated fluctuating asymmetry as shown by signed right-minus-lef t number of pegs having a frequency distribution not differing from a norma l distribution with a mean value of zero. Peg asymmetry was significantly n egatively related to mean number of pegs per leg. Peg asymmetry was relativ ely larger than asymmetry in femur length. A larger degree of peg asymmetry resulted in a larger degree of asymmetry in maximum frequency of chirps an d asymmetry in the duration of chirps produced by the two legs. Calls produ ced by males with experimentally manipulated numbers and asymmetries of peg s were used in a female phonotaxis experiment. Females preferred calls of m ales with a larger and more symmetrical number of pegs. Peg asymmetry diffe red in a field sample of mated and unmated males with mated males having a smaller degree of peg asymmetry. These results demonstrate that females can discriminate male asymmetry directly on the basis of calls.