Behavior of flies in the genus ceratitis (dacinae: Ceratitidini)

All organisms exhibit an array of discrete, specific behaviors. These behaviors may be seen as finetuned adaptations that, on the proximate level, form a bridge between the physiological needs of the organism, a variety of phylogenetic constraints, and the environment in which the organism lives. On an ultimate level, these behaviors are highly evolved patterns that withstand the acid test of continuous natural selection and optimize the reproductive success of the individual that enacts them. These principles are very well illustrated in analyses of tephritid behavior in general, and that of Ceratitis flies in particular. The genus Ceratitis encompasses some 78 species, several of significant economic importance (Table 17.1) (Hancock 1984; White and Elson-Harris 1992; De Meyer, Chapter 16). Paramount among these, in economic importance, is C. capitata (Wiedemann), the Mediterranean fruit fly, which is distributed in most tropical and temperate regions of the world, and constantly threatens to invade or reinvade new areas (Christenson and Foote 1960; Bateman 1972; Carey 1991). Other polyphagous flies of the genus have potential as invaders as well, and may become cosmopolitan pests in the future (Steyskal 1982; Chen and Tseng 1992). The impressive biological success of these flies is supported by numerous adaptations, morphological, physiological, and behavioral, which allow them to thrive in diverse habitats that exert a range of environmental pressures on individual flies. In this chapter we attempt to present a synthesis of the behaviors exhibited by these flies, focusing on C. capitata, the best-studied member of the genus. Attempting a view that integrates the various hierarchies that govern the behavior of individuals at each stage of the life cycle, we treat larval and adult behavior separately. Larvae of Ceratitis flies live fairly uncomplicated lives, ensconced as they are in the host fruit selected by their female parent. Nevertheless, as we show below, they are endowed with behaviors that allow them to utilize the host optimally, avoid predators and parasites, and pupate in the soil. Adult behavior is extremely complex, punctuated by the catholic host preferences of these flies, and their need to move around in heterogeneous environments, seeking carbohydrate and proteinaceous nutrition, mates, and oviposition sites. We present adult behavior from a foraging perspective, as each sex must forage sequentially for these resources (nutrition, mates, and oviposition hosts), constantly making decisions with grave reproductive consequences (Prokopy and Roitberg 1989). Thus, the chapter includes sections on larval behavior, and feeding, sexual, and oviposition behavior of adults. Given the economic importance of C. capitata and the practical implications of a thorough knowledge of sexual behavior and sexual selection in this species, this particular topic is covered in great detail in a separate chapter (Eberhard, Chapter 18).