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Psylla pyricola Foerster -- Psyllidae




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The pear psylla may be rated either as a principal pest or one of secondary importance, depending on the area in which fruit production occurs; however, Croft & AliNiazee (1999) rate it as primarily an indirect pest of pears in western North America.  There has been some effort to import exotic natural enemies for classical biological control in North America (Croft & Bode 1983), and several coccinellids, including Harmonia conformis, Harmonia dimidiata, and Dimus pumilo were imported in the late 1970's for control.  In 1963 the anthocorid Anthocoris nemoralis (F.) was imported and established from western Europe into British Columbia and later into the western United States.  Predators that were imported in the 1980's from Yugoslavia and northern Greece were Chrysopa carnea Steph., Synharmonia conglobata, Propylea quatourdecimpuncta and an encyrtid parasitoid Prionomitus mitratus (Dalm).  There is to date no record of establishment.  Another parasitoid, Trechnites psyllae (Ruschka) was imported from Greece and released in California and Oregon, but no establishment has been reported (Croft & AliNiazee 1999).


In Canada natural enemies were imported beginning in 1962, when shipments of the predator Anthocoris nemoralis (F.) were obtained from Switzerland, followed by A. menorum (L.), A. pilosus (Jak.) and the encyrtid parasitoid P. mitratus.  Field releases at Summerland, British Columbia in 1963 were in only small numbers (Clausen 1978).  However, a low number release of A. nemoralis at Summerland resulted in establishment.  The predator became very abundant at the release site by 1966 and had dispersed to other orchards at least 1.5 miles distant (McMullen & Jong 1967).  Prionomitus mitratus was recovered from 1st generation host nymphs in 1964, not only at the release site but at three other points up to 45 miles distant, although in very small numbers.  This parasitoid had previously been recorded from native Psyllidae on the Pacific Coast, and McMullen (1966) believed that it was already present in British Columbia before the release of the imported stocks.  The cecidomyiid parasitoid Endopsylla agilis Meij. was obtained from Germany after 1966, but no other information is available. 


In the United States stocks of P. mitratus and Trechnites psyllae (Ruschka) were imported from Switzerland during 1965, and releases in infested orchards in northern and central California during 1965-68 totaled 13,894 and 5,134, respectively.  However, again information is lacking regarding recoveries; but Jensen (1957) reported the P. mitratus as parasitic on several genera of Psyllidae in California.



REFERENCES:            [Additional references may be found at:   MELVYL Library ]


Burts, E. C. & W. R. Fischer.  1967.  Mating behavior, egg production and egg fertility in the pear psylla.  J. Econ. Ent. 60:  1297-1300.


Clausen, C. P.  1978.  Psyllidae.  In:  C. P. Clausen (ed.), Introduced Parasites and Predators of Arthropod Pests and Weeds: A World Review.  U. S. Dept. Agric., Agric. Handbk. No. 480.  545 p.


Croft, B. A. & W. Bode.  1983.  Tactics for deciduous tree fruit IPM.  Chapter 8, p. 219-70.  In:  B. A. Croft & S. C. Hoyt (eds.), Integrated Management of Insect Pests of Pome and Stone Fruit Insect Pests.  Wiley Intersci., New York.  456 p.


Croft, B. A. & M. T. AliNiazee.  1999.  Biological control in deciduous tree fruit crops, IN:  Bellows, T. S. & T. W. Fisher (eds.), Handbook of Biological Control:  Principles and Applications.  Academic Press, San Diego, New York.  1046 p.


Jensen, D. D.  1957.  Parasites of the Psyllidae.  Hilgardia 27:  71-99.


Madsen, H. F., P. H. Westigard & R. L. Sisson.  1963.  Observations on the natural control of the pear psylla, Psylla pyricola Forster, in California.  Canad. Ent. 95:  837-44.


Madsen, H. F. & T. T. Y. Wong.  1964.  Effects of predators on control of pear psylla.  Calif. Agr. 18(2):  2-3.


McMullen, R. D.  1966.  New records of chalcidoid parasites and hyperparasites of Psylla pyricola Forster in British Columbia.  Canad. Ent. 98:  236-239.


McMullen, R. D. & C. Jong.  1967a.  The influence of three insecticides on predation of the pear psylla, Psylla pyricola.  Canad. Ent. 99:  1292-97.


McMullen, R. D. & C. Jong.  1967b.  New records and discussion of predators of the pear psylla, Psylla pyricola Forster, in British Columbia.  J. Ent. Soc. Brit. Colum. 64:  35-40.


Metcalf, C. L. & W. P. Flint.  1939.  Destructive and Useful Insects. Ed. 2.  McGraw-Hill, New York & London.  981 p.


Nickel, J., L., J. T. Shimizu & T. T. Y. Wong.  1965.  Studies on natural control of pear psylla in California.  J. Econ. Ent. 58:  970-76.


Shimizu, J.  1970.  The influence of natural enemies on field-caged pear psylla.  Calif. Agr. (1970).Westigard, P. H. & H. F. Madsen.  1963.  Pear psylla in abandoned orchards.  Calif. Agr. 17(1):  6-8.