We observed couples for 5 minutes or until courtship started and ended. This meant that observations could extend beyond 5 minutes, if courtship started before 5 minutes but ended later than 5 minutes. Observation arenas were made using two microscope slides with vinyl-foam weather-stripping (5 mm thick) glued to them; on one slide, the weather-stripping had a 10 mm diameter hole bored in it, exposing the slide surface through which observations were made. After observations in which copulation was observed, females were dissected to see whether sperm was transferred. In all dissections, females that copulated carried sperm, thus courtship rounds that led to copulation were considered successful. We recorded behavior using a binocular stereomicroscope (model SMZ 1500, Nikon Instruments, Melville, NY, USA) with a digital camera (model DEI 750D, Optronics, Goleta, CA, USA) connected to a digital video-tape recorder (model HVR-M15AU, SONY, New York, NY, USA) that provided date/time stamps and a DVD recorder (model DMR-EZ28K, Panasonic, Newark, NJ, USA). Video-editing software (Handbrake, version 0.9.9.5530) was used to convert DVD files from VOB to MP4 format. Video-analysis software (Kinovea, version 0.8.15) was used for playback of the observations to determine antennal positions and durations of courtship components. Durations of courtship rounds were measured from the start of male antennation until the end of copulation. The durations of the two types of male antennation (simultaneous dipping and alternate waving) were measured to the nearest tenth of a second. We counted the number of dipping bouts and waving bouts per courtship round, and for dips, we counted the number of dips per dipping bout. Antennal spread at the top and bottom of dips was classified as intraocular, mideye, head or greater than head relative to the width of the female head. Position of male to female antennae at the bottom of dips was classified as above, equal to or below the female antennae. Often the male antennae were close together at the top of the dip and the separation widened as male antennae approached female antennae. The shape of the dip was classified by the change in spread between the top and bottom of the dip as inward (closer at bottom than top), straight (no change), slight (change in one category, e.g. mideye to head width), or large (change in more than one category, e.g. intraocular to greater than head width). Therefore, we measured multiple components of courtship, five of which were categorical and eight of which quantitative, either continuous or discrete.
|resource type||file upload|
|timestamp||Mar 23, 2020|