Hostname: page-component-586b7cd67f-r5fsc Total loading time: 0 Render date: 2024-11-24T11:46:09.607Z Has data issue: false hasContentIssue false
  • English
  • Français

SPECIALIZATION IN THE EGG STRUCTURE OF EXENTERUS (HYMENOPTERA: ICHNEUMONIDAE) IN RELATION TO DISTRIBUTION AND ABUNDANCE

Published online by Cambridge University Press:  31 May 2012

W. R. M. Mason
W. R. M. Mason
Affiliation:
Entomology Research Institute, Canada Department of Agriculture, Ottawa
Get access Rights & Permissions [Opens in a new window]

Abstract

Like all other Tryphoninae, the European species of Exenterus have eggs that are attached to the host by a stalk inserted into the host integument. Their eggs present an interesting series of evolutionary steps from the typical tryphonine condition in which the egg has a small single stalk with a knob-like anchor to an extremely specialized condition in which the stalk is doubled and its two parts migrate to opposite ends of the egg; the anchoring part of the stalk is concurrently enlarged until it half encloses the egg and functions as an extremely efficient organ of attachment to the host cuticle. In dry periods the simple type of stalk becomes brittle and easily broken, resulting in the death of the parasite. The specialized eggs with protected stalks are not subject to such hazards; thus species with specialized eggs can succeed in drier climates and can better survive droughty seasons. Correlated with these specializations is an increase in range of species, and greater abundance of individuals. The success of the European species introduced into North America for biological control has been roughly proportional to the amount of specialization in the egg structure. Little is known of the life histories of the American species of Exenterus but the few facts available do not appear to contradict the type of correlation exhibited by the European species.

Type
Articles
Information
The Canadian Entomologist , Volume 99 , Issue 4 , April 1967 , pp. 375 - 384
Copyright
Copyright © Entomological Society of Canada 1967

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Barclay, J. M. 1938. The oviposition habits of the species of the genus Exenterus parasitic on sawfly larvae. Annu. Rep. ent. Soc. Ont. 69: 29–31.Google Scholar
Clausen, C. P. 1932. The early stages of some tryphonine Hymenoptera parasitic on sawfly larvae. Proc. ent. Soc. Wash. 34: 49–60.Google Scholar
Cushman, R. A. 1940. A review of the parasite wasps of the Ichneumonid genus Exenterus Hartig. Misc. Publ. U.S. Dep. Agric. 354.Google Scholar
Dowden, P. B. 1962. Parasites and predators of forest pests liberated in the United States through 1960. U.S. Dep. Agric., agric. Handb. 226.Google Scholar
Finlayson, L. R., and Finlayson, Thelma. 1958. Parasitism of the European pine sawfly, Neodiprion sertifer (Geoff.) (Hymenoptera: Diprionidae), in southwestern Ontario. Can. Ent. 90: 223–225.CrossRefGoogle Scholar
Forsius, R. 1911. Zur Kenntnis einiger aus Blattvespenlarven erzogener Schlupfvespen. Medd. Soc. Fauna Fl. fenn. 37: 98–104.Google Scholar
Kerrich, G. J. 1952. A review, and a revision in greater part, of the Cteniscini of the old world (Hymenoptera: Ichneumonidae). Bull. Brit. Mus. nat. Hist., Ent. 2: 305–460.Google Scholar
Mason, W. R. M. 1962. Some new Asiatic species of Exenterini (Hymenoptera: Ichneumonidae) with remarks on generic limits. Can. Ent. 94: 1273–1296.CrossRefGoogle Scholar
McGugan, B. M., and Coppel, H. C.. 1962. A review of the biological control attempts against insects and weeds in Canada. Part II. Tech. Communication 2, Commonwealth Inst. biol. Control, Commonwealth Agric. Bur., Farnham Royal.Google Scholar
Morris, K. R. S. 1937. The prepupal stage in Ichneumonidae, illustrated by the life-history of Exenterus abruptorius, Thb. Bull. ent. Res. 28: 525–534.CrossRefGoogle Scholar
Morris, K. R. S., Cameron, E., and Jepson, W. F.. 1937. The insect parasites of the spruce sawfly (Diprion polytomum, Htg.) in Europe. Bull. ent. Res. 28: 341–393.CrossRefGoogle Scholar
Reeks, W. A. 1952. Establishment of Exenterus spp. (Hymenoptera: Ichneumonidae), parasites of the European spruce sawfly, near points of introduction. Can. Ent. 84: 76–86.CrossRefGoogle Scholar
Scheidter, F. 1934. Eiablage eines Lophyrus-Parasiten, des Exenterus marginatorius. Z. Pflkrankh. 44: 500–502.Google Scholar