Population Fluctuations of Adult Mediterranean Fruit Flies (Diptera: Tephritidae) in a Mediterranean Heterogeneous Agricultural Region

Abstract

We investigated the regional population fluctuations of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), in a Mediterranean setting located in the hills (700 m above sea level) of central Israel. The region is composed of commercial orchards, residential mixed-fruit gardens, and Mediterranean shrubs and forests. Adult C. capitata population in the studied region was sampled weekly for 2 years (1994–1995) with Trimedlure traps spread as grids of different scales (between 74–130 traps). No flies were trapped during the winter and early spring months. During the summer and fall, flies were caught sequentially in traps located on host trees (i.e., apple, fig, and mixed fruit-gardens with apricot, plum, and others) at varying times of maturation. Flies first appeared in 'Granny Smith' apple orchards (May–June), which are also the same places where the last adult flies were trapped during December. This fact points at the possibility that C. capitata overwinters as larvae in these orchards on nondecaying apple fruits. Small numbers of flies were caught in traps located on nonhost trees—with the exception of English walnut, which showed large trapping numbers between May and August and which seems to be related to the availability of large amounts of aphid honeydew that probably served to replenish energy reserves of the overwintering populations. Traps on abandoned fig trees, which have the apparent role for the expansion of the population in the summer, caught large numbers of flies between August and November. We conclude that the perpetuation of C. capitata in this Mediterranean setting reflects the ability of an overwintering population to realize its reproductive potential by exploiting the continuous succession of oviposition hosts during the warmer months.