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HOLLY LEAFMINER Phytomyza ilicis Curtis -- Agromyzidae (Contacts) ----- CLICK on Photo to enlarge &
search for Subject Matter with Ctrl/F. GO TO ALL: Bio-Control Cases Holly leafminer invaded
British Columbia, Canada, where it damaged leaves of English holly in
commercial and urban plantings. There
were five parasitoids liberated on Vancouver Island during 1936-1938 and on
mainland Canada in 1939 (Clausen 1978). Four species became established, with
Chrysocharis gemma (Walker) and Opius ilicis Nixon being most important. About 90% parasitization was caused by C gemma on Vancouver Island while O. ilicis
contributed ca. 90% of the parasitization on the mainland. These parasitoids usually prevent serious
damage to English holly in ornamental plantings, and Turnbull & Chant
(1961) considered this a complete biological control success. However, in commercially produced holly,
the parasitoids did not give completely satisfactory control (Dahlsten &
Hall 1999), therefore Turnbull & Chant (1961) and Munroe (1971) consider
biological control as partially to substantially successful in commercial
plantings. Clausen (1978)
remarked that the study of the natural enemies of the holly leaf miner in
England and their subsequent behavior when introduced into British Columbia,
demonstrated the risks and inherent difficulty in trying to judge, on the
basis of studies in the native home of a pest and its natural enemies, the
potential of each element of the latter when introduced into a new
environment. Chrysocharis gemma
was the dominant species in England, averaging 30-40% parasitism, with a
maximum of 71%. On the other hand,
the parasitization by O ilicis in England ranged from
0-0.3%, it being so scarce that on any basis of comparison it would have been
completely ignored, or at least would have been put at the bottom of any
priority list for introduction.
However, it was fully effective on the mainland of British Columbia,
as did C. gemma on Vancouver Island. Cameron (1941) discussed competition
between O. ilicis and C. gemma,
and stated that the latter is dominant when both occur in individual
hosts. He concluded that the total
mortality effected by the two parasitoids is greater than that which would be
attained by C. gemma alone, since the
mortality by O. ilicis, however small,
represents kill of hosts not parasitized by C. gemma. For further details
on this biological control effort, please see the following (Cameron 1939, 1941;
Downes & Andison 1940, McLeod 1954, 1962; Turnbull & Chant 1961). REFERENCES: [Additional references may be found at: MELVYL
Library ] Cameron, E. 1939. The holly leaf-miner (Phytomyza ilicis
Curt.) and its parasites. Bull. Ent.
Res. 30: 173-208. Cameron, E. 1941. The biology and post-embryonic development
of Opius ilicis n. sp., a parasite of
the holly leaf-miner (Phytomyza
ilicis Curt.). Parasitol. 33: 8-39. Clausen, C. P. 1978. Agromyzidae. In: C. P. Clausen, (ed.), Introduced parasites
and predators of arthropod pests and weeds:
A world review. U. S. Dept. of
Agriculture, Agric. Handbk. No. 480.
545 p. Dahlsten, D. L. & R. W. Hall. 1999. Biological control
of insects in outdoor urban environments.
In: Bellows, T. S. & T. W. Fisher (eds.), Handbook of Biological Control: Principles and Applications. Academic Press, San Diego, New York. 1046 p. Downes, W. & H. Andison.
1940. The establishment in
British Columbia of parasites of the holly leaf miner, Phytomyza ilicis
Curtis. J. Econ.
Ent. 33: 948-49. McLeod, J. H. 1954. Statuses of some introduced parasites and
their hosts in British Columbia. Ent.
Soc. Brit. Columbia Proc. (1953) 50: 19-27. McLeod, J. H. 1962. A review of the biological control
attempts against insects and weeds in Canada. Part I. Biological
control of pests of crops, fruit trees, ornamentals, and weeds in Canada up
to 1959. Commonwealth Inst. Biol.
Control, Tech. Commun. 2: 1-33. Munroe, E. G. 1971. Chap. 48.
Status and potential of biological control in Canada. p. 213-55. In: Biological control programmes against
insects and weeds in Canada, Commonwealth Inst. Biol. Contr. Tech. Comm. No.
4: 266 p. Turnbull, A. L. & D. A. Chant. 1961. The practice and
theory of biological control in Canada.
Canad. J. Zool. 39: 697-753. |