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HYMENOPTERA, Figitidae (Cynipoidea) -- <Images> & <Juveniles>

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Figitidae. -- Figitidae ; & -- These are parasitoids of the pupae of lacewings and Diptera. The family is divided into three subfamilies, primarily on the basis of the structure of the abdomen: the Anacharitinae, which have the abdomen distinctly petiolate and the second tergum longer than the third ( ), attack the cocoons of lacewings (Chrysopidae); the Aspiceratinae, in which the second abdominal tergum is narrow and much shorter than the third, attack the pupae of syrphid flies; the Figitinae, in which the second tergum is only slightly shorter than the third , attack the pupae of various Diptera (Borror et al., 1989).

Description & Statistics

Clausen (1940) distinguished figitids from eucoilids by placing each in a superfamily. He considered the Eucoilinae as the best known of parasitic Cynipoidea, which were limited in their host preferences to Diptera. Oviposition is in the early larval instars, and adults emerge from the puparia.

Cothonaspis rapae Westw. is a parasitoid of cabbage maggot, Hylemyia brassicae Bouché. Only the first two larval instars of the host are subject to attack, and darkness is necessary for oviposition, although adults are diurnal (James 1928, Malachanova 1930). It was believed that this caused maggots in leaves and stems to be immune from attack. Parasitoid adults are attracted to infested cabbage, and no attention is paid to free larvae or to those which have been moved to a fresh plant. The life cycle is completed in ca. 3 months, of which egg incubation takes 6 days and the larval period ca. 2 months. Hibernation is in the mature larval stage, and there are two generations per year.

Eucoila keilini Kieff. was studied by Keilin & Baume-Pluvinel (1913) and Kleidotoma marshalli Mshll. by James (1928). Conspicuous ventral thoracic processes are thought to be adaptive only and to serve in locomotion and respiration. However James (1928) could find no evidence of their use in locomotion by Kleidotoma. Both of these parasitoids have two generations per year. Parasitized host puparia are smaller than normal size, which effect seems to be consistent in all Diptera attacked by Figitidae.

Observations on Psilodora sp., attacking blowfly larvae in dung and carrion, were made by Roberts (1935). He find the life cycle to take an average of 35 days under summer conditions, but there was a tendency for the pupal period to be prolonged, and some individuals remained in diapause for 7 months. Hibernation took place in mature larvae or prepupae in the host puparium. No thelytoky was found.

In his discussion of Cynipoidea, Clausen (1940) separated the figitids from the eucoilids, although their hosts were the same. Figites anthomyiarum Bouché attacks larvae of various Diptera found in decaying meat (James 1928). Oviposition occurs only in 1st or 2nd instar larvae, and a preference is shown for those which have just hatched. A temporary paralysis occurs, which is of 1-2 minutes duration. The initial stimulus for oviposition is most certainly provided by the decaying meat rather than by the maggots themselves (Clausen 1940/1962). Adults emerge from the host puparium. The cycle from egg to adult takes ca. 60 days in summer, of which the egg, larval and pupal stages last 2-3, 38, and 20 days, respectively. There are 2 or possibly 3 generations per year and winter is passed as mature larvae in the host puparium. Adult life usually lasts only 8-9 days, and feeding is principally on juices of the host infested meat. There is a preoviposition period of ca. 2 days, and an examination of the reproductive tract revealed the presence of several hundred mature eggs, suggesting a high reproductive capacity.

Clausen (1940) discussed the superfamily Charipinae separate from the Figitidae, noting work by Haviland (1921) and Spencer (1926). An undetermined species of Charips studied by Haviland is a solitary internal parasitoid of late larval instars of Aphidius ervi Hal. in Macrosiphum urticae Kalt. and of other Aphidiinae in various aphids. Oviposition takes place frequently in the 3rd or early 4th instar Aphidius larva, although sometimes also in the late 2nd instar and while the aphid host is still alive. The female mounts on the back of the aphid, orients herself with her head toward that of the host and inserts her ovipositor perpendicularly. The trophic membrane surrounding the embryo usually disappears at the time of egg hatching, but occasionally it persists until after the first molt. The 1st instar larva is usually found ventrally in the posterior or anterior 1/3rd of the host body and between the nerve cord and intestine. The last instar larva emerges from the host through a break in the skin behind the head and completes its feeding externally. This ectoparasitic phase lasts only ca. 12 hrs. The pupal stage lasts 22-26 days, and adult emergence is effected by biting out an irregular hole dorsally in the host cocoon and aphid skin. Adults live only a short time, and feeding is on honeydew and plant sap.

Charips brassicae Ashm., studied by Spencer (1926) is similar in habits to that given by Haviland. The 1st instar larva is enveloped by the trophamnion, and feeding during the early stages is by diffusion through the thin integument. The aphidiine host is half grown when first attacked and reaches the pupa before death. The life cycle is completed in 26 days.

For detailed descriptions of immature stages of Figitidae, please see Clausen (1940/1962).

References: Please refer to <biology.ref.htm>, [Additional references may be found at: MELVYL Library]

Kerrich, G. J. 1940. Ent. Mon. Mag. 76: 15-17.

Quinlan, J. 1979. Bull. British Mus. Nat. Hist. 39: 85-133.

Weld, L. H. 1951. Cynipoidea. Private Printing, Ann. Arbor, Mich. 351 p.