Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/1998
Publication Date: N/A
Interpretive Summary: Tephritid fruit flies damage crops throughout the world and are often responsible for quarantines that hinder the development of agricultural exports in Caribbean basin countries. In some places natural enemies, such as parasitoids, kill substantial numbers of fruit flies, but in others they seem less effective. If the reasons for success and failure were better understood then countries, like the USA, that wish to import parasitoids for biological control of their own pest fly problems would be better able to pick the correct natural enemy for their particular needs. One difficulty parasitoids encounter, and one that could influence their ability to become established in certain environments, is to survive periods when flies are not available. These times might be cold or dry seasons, or times when host tree are not fruiting. One way of surviving difficult periods is to suspend development and conserve resources ("diapause"). Up until now there was little evidence of larval diapause in fruit fly parasitoids. However, ARS scientists in collaboration with colleagues at the Instituto de Ecologia (Xalapa, Mexico) have found diapause to be common in some species, and liable to occur as temperature and rainfall drop. This information may influence future parasitoid importation efforts and the rearing, holding, and shipping of parasitoids to be used in augmented releases.
Technical Abstract: We provide, for the first time, evidence for the existence of diapause in four native fruit fly (Diptera: Tephritidae) parasitoids inhabiting tropical environments. We worked in Central Veracruz, Mexico in perturbed tropical deciduous and subdeciduous forests and in diversified agroecosystems. The native parasitoid species, Doryctobracon areolatus (Szfipligeti), Utetes (B.) anastrephae (Viereck) (Hymenoptera: Braconidae) Aganaspis Pellenaroi (Brethes), Odontosema anastrephae Borgmeier (Hymenoptera: Eucoilidae), and the introduced species, Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae), all exhibited diapause. Doryctobracon crawfordi (Viereck) (Hymenoptera: Braconidae) and Aceratoneuromyia indica (Silvestri) (Hymenoptera: Eulophidae) (both larval- pupal parasitoids) and Coptera haywardi (Hymenoptera: Diapriidae) and Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae) (both pupal lparasitoids) did not exhibit diapause even though they were collected in the same region and the same time of year. Importantly, in diapausing species, not all populations exhibited the phenomenon and furthermore, in those that did, patterns were polymodal (proportion of a given population entering diapause fluctuated between 0.4-100% depending on species). All diapausing individuals dissected from fly pupae, were in the third instar larval stage. Diapause lasted up to 11 months (depending on the particular species).