Interaction Between Visual and Phonotactic Orientation During Flight in Magicicada Cassini (Homoptera: Cicadidae)

Abstract

Visual and phonotactic orientation often occur simultaneously in diurnalcicadas, and these animals generally have their largest sensoryelaboration in eyes and hearing organs. Phonotactic orientation occursprincipally during flight. Males and females of Magicicada cassinicommonly perform low-altitude (< 5 m) and short-distance (< 15 m)flights in their natural habitat at flight speeds of 3 to 6 m/s. Duringflight, the long body axis is tilted 10-degrees to 45-degrees, headupward. Wing beat frequencies of tethered animals at 24-degrees to26-degrees-C averaged 28.8 Hz. Body temperature in the field for flyingindividuals averaged 4.6-degrees-C above ambient.Compound eyes of females possess about 75 more facets than males, andthe binocular field of view for both is especially expandeddorso-frontally, frontally, and fronto-ventrally.The role of vision for phonoresponses, and in flight and landingbehaviour, was studied in nature by comparing controls with cicadas witheyes partly to completely covered with aluminium paint. Cicadas withtheir three ocelli covered behaved like controls and exhibitedlow-altitude and short-distance flights with landings on neighbouringshrubs, as did cicadas with only both caudal halves or both dorsalhalves of the compound eyes covered. Those with both compound eyescovered completely (with or without additionally covering the threeocelli) flew to higher altitudes and for longer distances. Higher andlonger flight courses were also seen in cicadas (A) with only onecompound eye covered, which in addition circled during walking andflight toward the side of unrestricted vision, (B) with both frontal orboth ventral halves of their compound eyes covered, and (C) with eitherthe binocular or monocular fields of the eyes covered. Thus, the pairedfronto-antero-ventral regions of the compound eyes provide usualinformation for habitat-dependent low-altitude flights and landings.Females with intact compound eyes and ocelli responded to playbacks ofjust the frequency/intensity sweep at the end of the buzz in callingsongs of a male by flying within 1.2 m above the ground and landing on anylon screen-covered small bush directly above the loudspeaker fromdistances of 2 to 8 m, mostly from lower vegetation. Males that wereblinded, or blinded and deafened, sang less and flew less than normalmales. However, they performed all of those behaviours, and all alsowalked and fed.