Parasitoids of Fruit-Infesting Tephritidae

Doryctobracon Enderlein, 1920: 144. Type species: Doryctobracon conjungens Enderlein, 1920 (original designation).

Synonym: Parachasma Fischer, 1967 (Fischer 1977).

In many of the publications prior to 1980, the species of Doryctobracon were placed either in the genus Opius or in the genus Biosteres. The name Parachasma was also used for about 10 years prior to the discovery by Fischer (1977) that Doryctobracon, previously included in a different subfamily, was the same as Parachasma.

Occipital carina absent (Figs. 1, 2). Labrum varying from almost completely concealed to partially but distinctly exposed below ventral margin of clypeus; ventral margin of clypeus varying from very weakly sinuate, nearly truncate (Fig. 7), to strongly sinuate and produced ventrally to form a distinct median tooth or lobe. First flagellomere almost always shorter than second, and first flagellomere with dense patch of close-set, curved placode sensilla on outer side. Propleuron always without oblique carina dorsad propleural flange. Notauli deep at anterior margin in nearly all species, weak to absent posteriorly, rarely meeting in a weak, median pit (midpit usually absent); notauli always unsculptured. Postpectal carina absent. Hind tibia dorso-posteriorly without basal carina. Fore wing (Fig. 3) with second submarginal cell short; m-cu arising basad or directly in line with 2RS, only very rarely (1% of specimens in certain species) arising distad 2RS. Hind wing (Fig. 4) with RS absent basally, represented only by an infumate crease distally in a few species; m-cu long, well-developed though not tubular, nearly reaching wing margin, usually represented by a well-pigmented crease. Metasomal terga always unsculptured beyond petiole. Ovipositor always very long (Figs. 5, 6). For additional details, see Wharton (1997).

Doryctobracon is readily distinguished from other Opiinae with small second submarginal cells by the absence of an occipital carina, the sinuate margin of the clypeus, relatively reduced notauli, and the origin of fore wing m-cu basad or directly in line with 2RS. The species of Doryctobracon also have shorter, thicker flagellomeres clothed with shorter, thicker setae than do nearly all species of Diachasmimorpha, Fopius, Rhynchosteres, and Psyttalia. Further, they have a shelf formed behind a carinate flange where the anterior declivity of the mesonotum meets the pronotal collar dorsally.

Unless you are already on this page, considerably more information on species groups and use in biological control can be found on the Doryctobracon page (and associated links) of the Paroffit website page: http://mx.speciesfile.org/projects/8/public/public_content/show/13335?content_template_id=88

Doryctobracon is known only from the New World, ranging from extreme southern United States (Florida and a few old records from Texas) through Mexico and much of the Caribbean to northern Argentina. There are no records from Chile. As of 2012, there are also no records of successful biological control introductions outside the New World, though there have been some attempts. Thus, at present, Doryctobracon is confined to the Nearctic and Neotropical regions. See Ovruski et al. (2000) for summary of published information.

There are about a dozen species of Doryctobracon, and these can be divided into two readily-recognizable species groups. The two species groups are easily separated from one another on the basis of the propodeal sculpture. In the first group, the propodeum is areolate (Fig. 1). In the second group of species, the propodeal sculpture is reduced to two apical ridges (Fig. 2). In the key below, I have not included the few species for which there are no host records. I have also not included D. capsicola, which attacks tephritids in seed capsules of Manihot esculenta (cassava or yuca). Further information on identification of these species, including dichotomous keys that include D. capsicola, can be found in Fischer (1977) and Wharton and Marsh (1978).

Key to species of Doryctobracon reared from fruit-infesting Tephritidae

1. Propodeum areolate, as in Fig. 1. (go to 2)
1a. Propodeal sculpture reduced to two apical ridges, as in Fig. 2. Propodeum never with complete median areola. (go to 6)

2. Fore wing yellow basally and black at the tip (Fig. 3). (go to 3)
2a. Fore wing either uniformly clear (hyaline) (Figs 4, 5) or uniformly darkened (infumate). (go to 4)

3. Head and hind femur mostly black (see Fig. 3): The top half of the head is almost always black, and sometimes the entire head is black. D. zeteki (Muesebeck)
3a. Head and hind femur mostly or entirely yellow to yellow-orange. This species is otherwise quite similar to D. zeteki. D. auripennis (Muesebeck)

4. Legs darker. Fore and middle tibia and femur dark brown to black. Known only from Florida. Doryctobracon anastrephilus (Marsh)
4a. Legs not as dark. Fore and middle tibiae yellow or yellow-orange. Widely distributed. (go to 5)

5. Fore wing clear (hyaline) (Figs 4, 5). Doryctobracon areolatus (Szépligeti)
5a. Fore wing darkened (infumate). Doryctobracon fluminensis (Costa Lima)

6. Stigma of fore wing brightly colored (yellow) (Fig. 6). Doryctobracon brasiliensis (Szépligeti)
6a. Stigma of fore wing dark; wings do not have yellow markings. (go to 7)

7. Head and mesosoma (thorax + propodeum) almost always black and remainder of abdomen (beyond propodeum) almost always bright yellow (Fig. 7). Primarily attacks Toxotrypana curvicauda Gerstaecker in papaya and thus this species is also identifiable on the basis of the host and host plant from which it is reared. Doryctobracon toxotrypanae (Muesebeck)
7a. Thorax and abdomen usually orange, red, or reddish-orange (Fig. 8). (go to 8)

8. Widely distributed, occurring from northern Mexico to northern Argentina. Doryctobracon crawfordi (Viereck)
8a. Known only from the island of Trinidad. Otherwise difficult to distinguish from D. crawfordi. There are slight differences in the density of setae on the frons (behind the antennal bases), with the frons being more densely hairy in D. crawfordi. The midline of the propodeum (between the parallel ridges) is also sometimes more deeply impressed in D. crawfordi than in D. trinidadensis, and forms a distinct groove. Doryctobracon trinidadensis (Gahan)

Group 1
This group includes species with propodeal sculpture areolate. Fig. 1 shows typical sculpture in this group.

Group Members:
Doryctobracon zeteki (Muesebeck)
Doryctobracon auripennis (Muesebeck)
Doryctobracon anastrephilus (Marsh)
Doryctobracon areolatus (Szépligeti)
Doryctobracon fluminensis (Costa Lima)

These five species can be separated into two subgroups based on the color pattern of the wings. In two of the species, D. auripennis and D. zeteki, the fore wing is yellow basally and black at the tip (Fig. 3). In the other three species, the fore wing is either uniformly clear (hyaline) (Fig. 4) or uniformly darkened (infumate).

Group 2
This group includes species with propodeal sculpture reduced to two apical ridges. Fig. 2 shows the typical propodeal sculpture in this group.

Group Members:
Doryctobracon brasiliensis (Szépligeti)
Doryctobracon toxotrypanae (Muesebeck)
Doryctobracon crawfordi (Viereck)
Doryctobracon trinidadensis (Gahan)

Doryctobracon brasiliensis is readily separated from the other three species in this group by the brightly colored (yellow) stigma of the fore wing (Fig. 6). The other three species have the stigma dark and the wings do not have yellow markings. However, among the few species of Doryctobracon for which there are no host records, there is another one with a bright yellow stigma known only from one specimen collected in Tucuman, Argentina. This is Doryctobracon homosoma (Fischer). Identification of any Doryctobracon material reared from that region of Argentina would need to take this into account.

The best known and most widespread species, D. crawfordi (Viereck) and D. areolatus (Szépligeti), attack tephritid pests (primarily members of the genus Anastrepha) in a variety of cultivated and native edible fruits in Latin America. There are also several other species that are known to attack fruit-infesting tephritids (Wharton and Marsh 1978). However, at least one species attacks tephritids in stems and one other species, Doryctobracon anneae Wharton, is only known to attack a species of tephritid breeding in flower heads of Dahlia spp. (Asteraceae) (Wharton and Norrbom 2013).

Available information suggests that all species of Doryctobracon attack late instar larvae of their host tephritids; and as in all other Opiinae, they emerge from the host puparium.

Males of the species of Doryctobracon examined thus far share with Fopius and Diachasmimorpha paired Hagen’s glands with exceptionally long, thin filaments. These glands occupy much of the lateral portions of the abdominal cavity. For further comments about these glands, see Diachasmimorpha page.