Daily Activity and Territoriality of Drosophila elegans in Sukarami, West Sumatra, Indonesia

Abstract

Males of Drosophila elegans hold mating territories on individual Ipomoea flowers which remain to open for a single day. Here we investigated daily activity and territoriality of this species in Sukarami, Indonesia. Flies of both sexes spent the night in withered flowers and left them from morning to evening. As the day passed, the number of flies on newly opened (day-O) flowers increas·ed and peaked in the evening. On day-O flowers, males usually held territories, but seemed to be unable to defend territories when the number of flies on flowers increased. Territorial males on day-O flowers were larger than males which remained in day-1 flowers, indicating that larger males left withered flowers earlier than smaller ones to secure territories on day-O flowers. Laboratory experiments confirmed the superiority of larger males in territorial defense. In the female, such relation between body size and daily behavior was not observed. In the evening, flies became inactive and stayed rather still on flowers. Females laid eggs on flowers from morning to evening only on the day of blooming. The distribution of eggs among flowers was random.