Is A nastrepha obliqua ( D iptera: T ephritidae) a natural host of the N eotropical parasitoids D oryctobracon crawfordi and O pius hirtus ?

An understanding of the search, selection and host use behaviours of parasitoids that have the potential to be used as biological control agents is becoming increasingly important. We studied under laboratory conditions the host suitability of A nastrepha obliqua ( M acquart) and A nastrepha ludens ( L oew) larvae for the parasitoids D oryctobracon crawfordi ( V iereck) and O pius hirtus ( F ischer), which are native to the A mericas. By counting the oviposition scars on the puparium, we found that both types of larvae were equally attacked; however, the pupa dissections revealed that different numbers of eggs were laid in each type of larvae. The A . obliqua larvae were significantly less parasitised than those of A . ludens , and immature insect development or adult emergence was not in either parasitoid species. Dissections of the parasitised A . obliqua pupae also showed that the immature parasitoids of both species died by encapsulation and melanisation, and there was a high proportion of unemerged adult flies. By contrast, A . ludens parasitised pupae contained several viable immature parasitoids that subsequently emerged as adult parasitoids. These results indicated contrasting suitability conditions of A . ludens and A . obliqua larvae as hosts of O . hirtus and D . crawfordi parasitoids, which suggest that A . obliqua is not a natural host for either parasitoid species. These findings will improve the understanding for the use of these parasitoid species in projects for biological control against economically important fruit flies of the genus A nastrepha .