Order: Hymenoptera Linnaeus, 1758
Family: Braconidae Nees, 1811
Subfamily: Aphidiinae Haliday, 1833
Diaeretus leucopterus
(Haliday, 1834)
Aphidius leucopterus Haliday, 1834. Entomological Magazine, 2:93–106.
Material examined: 3♀ 1♂, ex. Eulachnus agilis (Kaltenbach), on Pinus halepensis Miller, during April 2010, 2011, and 2018, Tunisia, ISA CM (35° 54′ 58″ N, 10° 33′ 36″ E).
Diagnosis: (female—Fig. 1). Body length 1.7–1.9 mm. Head sparsely setose, wider than thorax at tegula. Eyes medium sized. Malar space 0.25–0.30 times longitudinal eye diameter. Tentorial index 0.6–0.7. Clypeus flat, with 4–6 long setae. Maxillary palpi four-segmented, labial palpi 2-segmented. Antenna filiform, 16-segmented. Mesoscutum (Fig. 2a) smooth and shiny with rows of sparse setae along the trace of effaced notaulices. Forewing (Fig. 2b) stigma triangular, its length 2.4–2.6 times its maximum width, and 1.9–2.1 times R1. Vein r&RS short, not reaching the end of stigma, its length 0.85–0.95 times R1. Propodeum (Fig. 2c) smooth with the anterolateral and central carinae which extended near the spiracles. Petiole (Fig. 2d) stout, slightly constricted after spiracles, then parallel sided, 3 times its width at spiracles. Gaster lanceolate. Ovipositor sheath (Fig. 2e) stout, sub quadrate and apically truncated. Recorded diagnostic characters agree with that reported by Kaliuzhna (2014).
Coloration: Generally dark, head and mesosoma black, gaster dark brown. Antenna brown, with dark brown scape and pedicel. Legs light brown with yellow patches at tip of segments. Mummified aphids of yellowish brown color were mainly attached to the underside of the needles (Figs. 3a, b). Parasitoids were emerged 7 days post-collection by cutting a circular hole at the posterior part of the mummy above the cauda (Fig. 3c).
The hyperparasitoid Asaphes suspensus (Nees) (Hymenoptera, Pteromalidae) was also emerged from the mummified aphids (2♀ 3♂, same data as for the parasitoid, April 2010 and 2011). This species was already recorded in North Africa in Morocco (Vago 2002). It is a generalist hyperparasitoid of numerous aphid species excluding pine aphids (Gibson and Vikberg 1998). The emergence hole of the adult hyperparasitoid, with irregular margines, is distinctly smaller than the corresponding hole of the primary parasitoid and cutted at the anterio-dorsal area of the mummy (Fig. 3d). Another species, Asaphes vulgaris Walker (Hymenoptera, Pteromalidae), was also recorded as a hyperaprasitoid of D. leucopterus via E. rileyi (Suay Cano et al. 1998). Further records regarding the associations of the generalist hyperparasitoids of the genus Dendrocerus Ratzeburg (Hymenoptera, Megaspilidae) with D. leucopterus, both in Eastern (Takada 1973) and Western (Starý 1977) Palaearctics, indicate the presence of diverse food webs rooted on Eulachnus spp. to be explored by subsequent studies.
Diaeretus leucopterus was recorded for the first time not only in Tunisia but also in the African continent in association with E. agilis on P. halepensis. Diaeretus leucopterus is a widely distributed species in the Western Palaearctic, including some European countries (Mackauer and Starý 1967; Kavallieratos et al. 2004; Kaliuzhna 2014) and some countries of the Eastern Palaearctic (Starý and Schlinger 1967; Takada 1968; Chen and Shi 2001; Starý et al. 2010) or Oriental (Starý and Ghosh 1983). Several Mediterranean countries, including France, Greece, and Italy, have been recorded as common areas of distribution of D. leucopterus, from where it might be accidentally introduced into the North African area (Tunisia). According to Sghaier and Claustriaux (2015), P. halepensis is of mixed origin since some P. halepensis forests are assumed to originate from the nearby countries, i.e., Africa (Morocco), Southern Europe (Italy), and Western Asia (Israel).
Siphonatrophia cupressi (Swain) (Hemiptera, Aphididae, Aphidinae) has been recently recorded in Tunisia on Cupressus sempervirens L. parasitized by an unknown parasitoid species (Ben Halima Kamel and Mdellel 2017). Since both aphids (E. agilis and S. cupressi) and their host plants (P. halepensis, C. sempervirens) were found in the same area (ISA CM), the association of D. leucopterus with S. cupressi seems expectable. It should be noted that the 2 aphid genera, Eulachnus and Schizolachnus Mordvilko (Hemiptera, Aphididae, Lachninae), were recorded as hosts of D. leucopterus in the Mediterranean area (Kavallieratos et al. 2004). However, further field efforts are necessary to confirm this hypothesis. Few host records of D. leucopterus including Mindarus abietinus Koch (Hemiptera, Aphididae, Mindarinae) (Čapek 1960) and Brachycaudus cardui (L.) (Hemiptera, Aphididae, Aphidinae) (Fulmek 1968) look doubtful and need verification. Although some other coniferous-associated aphid species, mainly of the genus Cinara Curtis are present in Tunisia (Ben Halima Kamel 2012; Ben Halima Kamel et al. 2019), they have not been found parasitized yet (Rakhshani et al. 2019). One other European parasitoid of Eulachnus aphids, Praon bicolor Mackauer (Hymenoptera, Braconidae, Aphidiinae) (Kavallieratos et al. 2004), was found in the Mediterranean counties (Tremblay 1975; Núñez-Perez and Tizado 1996). It is an uncommon species, while its occurrence in North Africa has not been documented yet. The Nearctic aphids of the genus Essigella del Guercio are biogeographically associated with pine trees in North America (Blackman and Eastop 1994; Théry et al. 2018). Diaeretus essigellae Starý & Zuparko (Hymenoptera, Braconidae, Aphidiinae) was described from Essigella californica (Essig) (Hemiptera, Aphididae, Lachninae) on Pinus spp. in California (Starý and Zuparko 2002). It is closely related to D. leucopterus, but it is immediately separated by the absence of propodeal carinae. However, it is rather unlikely to occur in Tunisia, since pine seedlings are not transported from North America to Tunisia. A comparison of both Diaeretus species, using DNA sequences, can provide further data about the identity of these taxa and their associated host aphids.
