Ecological evidence for diapause in four native and one exotic species of larval-pupal fruit fly (Diptera: Tephritidae) parasitoids in tropical environments

We provide ecological evidence for the existence of diapause in 4 native and an exotic species of larval-pupal 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 during 4 yr (1993-1997). The native parasitoid species Doryctobracon areolatus (Szepligeti), 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. Importantly, none of the 6 Anastrepha species serving as hosts for these parasitoids entered diapause. The larval-pupal parasitoids Doryctobracon crawfordi (Viereck) (Hymenoptera: Braconidae; native) and Aceratoneuromyia indica (Silvestri) (Hymenoptera: Eulophidae; introduced) and the pupal parasitoids Coptera haywardi (Hymenoptera: Diapriidae; native),and Pachycrepoideus oindemiae (Rondani) (Hymenoptera: Pteromalidae; introduced) did not exhibit diapause even though they were collected in the same region and at 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 and 100% depending on species). All diapausing individuals dissected from ny pupae were 3rd instars. Diapause lasted up to 11 mo (depending on the particular species) and was predominantly observed in fly pupae collected between the months of September and December (time of pear when temperature and rainfall drops and days become shorter). Based on observations on tree fruiting phenology, we conclude that diapause is an effective mechanism allowing parasitoids to bridge periods during which fruit ny hosts (i.e.,larvae) are scarce or not available. We discuss our findings in light of their ecological and practical implications.