Tephritid fruit fly parasitoids use fruit-derived chemical cues and the vibrations that result from larval movements to locate hosts sequestered insi

Ultimately, the success of augmentative fruit fly biological control depends upon the survival, dispersal, attack rate and multi-generational persistence of mass-reared parasitoids in the field. Foraging for hosts, food and mates is fundamental to the above and, at an operational level, the choice of the parasitoid best suited to control a particular tephritid in a certain environment, release rate estimates and subsequent monitoring of effectiveness. In the following we review landscape-level and microhabitat foraging preferences, host/fruit ranges, orientation through environmental cues, host vulnerabilities/ovipositor structures, and inter and intraspecific competition. We also consider tephritid parasitoid mating systems and sexual signals, and suggest the directions of future research.

Endoparasitoid larvae may eliminate heterospecific competitors by physical or physiological means. The outcomes of these intrinsic competitions are o

The use of irradiated hosts in mass rearing tephritid parasitoids represents an important technical advance in fruit fly augmentative biological control. Irradiation assures that fly emergence is avoided in non-parasitized hosts, while at the same time it has no appreciable effect on parasitoid quality, i.e., fecundity, longevity and flight capability. Parasitoids of fruit fly eggs, larvae and pupae have all been shown to successfully develop in irradiated hosts, allowing a broad range of species to be shipped and released without post-rearing delays waiting for fly emergence and costly procedures to separate flies and wasps. This facilitates the early, more effective and less damaging shipment of natural enemies within hosts and across quarantined borders. In addition, the survival and dispersal of released parasitoids can be monitored by placing irradiated sentinel-hosts in the field. The optimal radiation dosages for host-sterility and parasitoid-fitness differ among species, and considerable progress has been made in integrating radiation into a variety of rearing procedures.

Augmentative biological control of tephritid fruit flies would benefit from: (1) synthetic attractants to monitor the survival and dispersal of released parasitoids and (2) synthetic oviposition stimulants to reduce production costs of parasitoid species that are now prohibitively costly to mass-rear. Utetes anastrephae (Viereck) is a widespread and sometimes common opiine braconid parasitoid of several pest Anastrepha spp. Despite its host range, distribution and abundance, it has attracted relatively little research and little is known of its chemical ecology. Its orientation was determined towards two chemical cues hypothesised to be useful at two spatial scales: (1) limonene derived from fruit is presumably abundant and widely dispersed and might identify from a distance patches of potentially host-containing fruit; and (2) para-ethylacetophenone (PEA), a volatile emitted by a number of tephritid larvae, presumably in relatively small amounts, and which could serve as short-range cue or oviposition stimulant. Various concentrations of limonene proved attractive to both females and males, perhaps to the later as a means of locating females accumulated in the vicinity of limonene-emitting host plants. PEA at the concentrations tested did not influence oviposition in U. anastrephae, although it did so for Diachasmimorpha longicaudata (Ashmead), another opiine tephritid parasitoid, previously known to respond to PEA and included in the experiment as a positive control. Limonene at the concentrations tested had no effect on oviposition in either species. These results advance efforts to synthesise attractants and oviposition stimulants for alternative candidates for augmentation such as U. anastrephae.