Pteromalidae, Dalman, 1820

Shimbori, Eduardo Mitio, Costa, Valmir Antonio & Zucchi, Roberto Antonio, 2020, Annotated checklist and illustrated key to parasitoids (Hymenoptera: Diapriidae Eulophidae and Pteromalidae) of fruit flies (Diptera, Tephritidae) in Brazil, Zootaxa 4858 (1), pp. 53-70 : 61

Family Pteromalidae (Hymenoptera, Chalcidoidea)

There are 3,506 species in 588 genera of Pteromalidae worldwide ( Noyes 2019). The number of subfamilies varies depending on the authority, but the most widely accepted classification comprises 31 ( Noyes 2002; 2019). This large number reflects its polyphyletic nature on the one hand, and the high proportion of monotypic subfamilies on the other ( Peters et al. 2018). In the Neotropics, there are 476 species in 155 genera ( Noyes 2019), of which 156 species in 65 genera are found in Brazil ( Costa 2019). Knowledge of the Neotropical fauna is only incipient, with most species yet to be described ( Hanson & Heydon 2006). No combination of characters exists to distinguish this family. The most recent phylogenies are consistent in recovering the family as polyphyletic, which to a great extent is responsible for the lack of morphological cohesion ( Munro et al. 2011; Heraty et al. 2013)

Since Pteromalidae is not a natural group, generalizations on its biology are difficult, and meaningless in an evolutionary perspective. Nevertheless, it is possible to say that pteromalids are in most cases ectoparasitoid idiobionts on pupae of Coleoptera and Diptera , developing inside the puparium case ( Hanson & Heydon 2006). Most of the knowledge on biology was acquired through examination of two unrelated subfamilies, Pteromalinae and Spalangiinae ( Peters et al. 2018) . Even though the two groups have relatively distant evolutionary histories and very distinct morphologies, they possess several biological traits in common, and all the representatives of parasitoids on fruit-infesting tephritids in Brazil belong to these subfamilies. Pteromalids are usually synovigenic, requiring the female to feed, usually on the host, to acquire the necessary nutrients for oogenesis ( Simmonds 1953; Doutt 1964; Legner & Gerling 1967; Keller & Sullivan 1976), but also as water-intake strategy ( Bezerra da Silva et al. 2019a). Host-feeding by Pachycrepoideus vindemmiae (Pteromalinae) , for instance, usually occurs in young pupae ( Phillips 1993), and may increase host mortality rate ( Bezerra da Silva et al. 2019b). This is the only Pteromalinae known to attack fruit flies in Brazil. For the Spalangiinae , four species have been recorded in Brazil attacking tephritids, all in the genus Spalangia . It is likely that many species in that genus occasionally parasitize fruit flies due to their polyphagous habit, as demonstrated by Silva et al. (2020), who obtained five species of Spalangia using sentinel puparia of Ce. capitata . For two of the five species (i.e. S. leiopleura and S. impunctata ), there are no previous association records with fruit flies. The two species were not included in our results by the absence of association with host plants. For any species of Spalangia reared from tephritids, checking the identification key provided by Gibson (2009) is strongly recommended.