Mediterranean Fruit Fly leks: factors affecting male location

1. The mating system of Mediterranean Fruit Flies (Ceratitis capitata, Diptera: Tephritidae) is based on male leks which form within the canopies of certain trees. In this study the following hypotheses are tested: (a) fly location depends on microclimate and illumination and (b) larger and heavier males occupy preferred locations in leks. Accordingly, systematic quantitative observations of diel three-dimensional (3-D) locations of lekking C. capitata males were performed in field and field cage studies.

2. Fly locations were found to vary significantly during the activity hours.

3. Medflies were generally found calling from highest and most exterior locations during early morning and late afternoon hours. During the hottest hours (1200–1500) flies occupied lower locations within the tree canopy, and interior locations from 1000 to 1500.

4. Fly location (from 1000 to 1700) was correlated with the azimuth of the sun. However, the mean azimuth range of fly location was limited to 85° (59·45°–143·94°).

5. Both in the field and in the field cage the temperature, relative humidity and light intensity beneath the leaves on which the males perched were closer to the microclimate beneath fully shaded leaves than to microclimates beneath leaves exposed to direct sunlight.

6. It is concluded that male medflies occupy locations which confer suitable microclimates for calling and copulating, and suitable 3-D locations within the canopy which provide protection from predators, wind, direct sunlight and water loss.