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HYMENOPTERA Pteromalidae, (Cleoneminae) (Chalcidoidea) -- <Images> & <Juveniles>

Description

The subfamily was once considered as a separate family, Cleonymidae. Pteromalidae now includes the former separate families, Cleonymidae, Miscogasteridae and Spalangiidae, which have been designated subfamilies Cleoneminae, Miscogasterinae and Spalangiinae, respectively. For the present, discussions of these various subfamilies will be separate because of considerable distinctness among them.

Three species for which some information is available are Schizonotus sieboldi Ratz. (Cushman 1917, Dowden 1939), S. paillotti F. & F. (Faure 1926) and Cheiropachys colon L. (Russo 1926, 1938).

Schizonotus sieboldi is gregarious and external on the pupae of Plagiodera versicolor Laich. and closely related chrysomalid beetles in the northeastern U.S. and Europe. Dowden (1939) indicated that it is an important factor in natural control of this host. Adult parasitoids occur in protected places and winter and attack the first brood of hosts in springtime. During oviposition the ovipositor is thrust beneath the pupa from the side, and one or more eggs are laid on the thorax between the appendages, although sometimes also on the abdomen or dorsum. Adult females feed upon host body fluids that exude from the puncture made in the dorsum after oviposition. Clausen (1940) commented that this is one of the few parasitic species that can develop externally upon exposed hosts, although the larvae are found between the body of the fixed host and the leaf, so that such conditions simulate the confined quarters of a burrow or cocoon.

Schizonotus paillotti differs from S. sieboldi in being hyperparasitic on some Lepidoptera through Apanteles in Europe. It is a solitary external parasitoid of the mature larva in the cocoon. Females feed on host body fluids prior to oviposition through a constructed feeding tube.

Solitary Cheiropachys colon parasitizes mature larvae of Scolytidae in Europe externally. Hosts are paralyzed at the time of oviposition, and the large egg is deposited on the body. Sex ratios favor females 5.5:1.

Biology & Ecology

The subfamily was once considered as a separate family, Cleonymidae. Pteromalidae now includes the former separate families, Cleonymidae, Miscogasteridae and Spalangiidae, which have been designated subfamilies Cleoneminae, Miscogasterinae and Spalangiinae, respectively. For the present, discussions of these various subfamilies will be separate because of considerable distinctness among them.

Three species for which some information is available are Schizonotus sieboldi Ratz. (Cushman 1917, Dowden 1939), S. paillotti F. & F. (Faure 1926) and Cheiropachys colon L. (Russo 1926, 1938).

Schizonotus sieboldi is gregarious and external on the pupae of Plagiodera versicolor Laich. and closely related chrysomalid beetles in the northeastern U.S. and Europe. Dowden (1939) indicated that it is an important factor in natural control of this host. Adult parasitoids occur in protected places and winter and attack the first brood of hosts in springtime. During oviposition the ovipositor is thrust beneath the pupa from the side, and one or more eggs are laid on the thorax between the appendages, although sometimes also on the abdomen or dorsum. Adult females feed upon host body fluids that exude from the puncture made in the dorsum after oviposition. Clausen (1940) commented that this is one of the few parasitic species that can develop externally upon exposed hosts, although the larvae are found between the body of the fixed host and the leaf, so that such conditions simulate the confined quarters of a burrow or cocoon.

Schizonotus paillotti differs from S. sieboldi in being hyperparasitic on some Lepidoptera through Apanteles in Europe. It is a solitary external parasitoid of the mature larva in the cocoon. Females feed on host body fluids prior to oviposition through a constructed feeding tube.

Solitary Cheiropachys colon parasitizes mature larvae of Scolytidae in Europe externally. Hosts are paralyzed at the time of oviposition, and the large egg is deposited on the body. Sex ratios favor females 5.5:1.

The eggs had been described for only the three species by 1940 (Clausen 1940). Those of S. paillotti and S. sieboldi are elongate-oval or somewhat cylindrical in outline, and that of C. colon (Fig. 48A) is narrowed at both ends, with the anterior and drawn out into stalk-like form and at times folded back upon the main body after deposition. In S. paillotti and C. colon, the chorion is clothed with minute spicules though sparsely so in the last named species, whereas S. sieboldi bears instead a fine reticulation on one side.

The 1st instar larvae of the family are hymenopteriform, with small sensory setae and the integumentary setae may be uniformly distributed or in bands at the segmental margins. The respiratory system is equipped with spiracles on the mesothorax and first three abdominal segments.

The 2nd to 5th instar larvae present no distinctive characters. The sensory setae and integumentary spines are minute. Nine pairs of spiracles appear on the fifth instar, these being situated on the second and third thoracic and the first seven abdominal segments.

For details on the immature stages of Cleonymidae, please see Clausen (1940/62).

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