SIRFIDOS AFIDOFAGOS (DIPTERA, SYRPHIDAE): IDENTIFICACIÓN RÁPIDA A CAMPO DE ESTADOS PREIMAGINALES Y LISTA DE ENEMIGOS NATURALES DE LAS ESPECIES MÁS FRECUENTES EN CEREALES Y FORRAJES EN LA PROVINCIA DE BUENOS AIRES (ARGENTINA)

Résumé

Keys to preimaginal stages of the five species of aphidophagous syrphids more frequenly found in
differents crops and pastures in Argentina: Allograpta exótica (Wied.), Syrphus phaeostigma Wied., Platycheirus stegnus Say, Pseudodorus clavatus (Fabricius) and Ocyptamus argentinus (Curran), were made for
a quick identification of these species in ecological studies. It was not possible to make keys to eggs since
these are not easily separated with a naked eye. Both larvae and pupae present stable color patterns
characteristics of each species and in the case of larvae, characteristics patterns of each instar inside each
species. The following natural enemies were found in the surveys: one entomopathogen (Entomophtora
muscae), four parasitoids (Diplazon laetatorius (Fabricius), Callaspidia sp., Encyrtus sp. and an egg
parasitoid) and a predator spider, Thomisus sp. (Araneae, Thomisidae).