Effects of a fruit and a host-derived compound on orientation and oviposition in Utetes anastrephae, a little studied opiine braconid (Hymenoptera) parasitoid of Anastrepha spp. fruit flies (Diptera: Tephritidae)

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 long-icaudata (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.