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Eucalyptus trees had few insect pests or diseases for over a century in California   However, a community of at least three feeding guilds of insects, including borers, defoliators and sap-feeding insects gradually invaded but most are not posing serious threats to the survival of some eucalyptus species where irrigation is adequate (Paine et al, 2000).


Of particular importance are the Longhorn borers, Phoracantha semipunctata F., P. recurva; Tortoise beetle, Trachymela sloanei, Snout beetle, Gonipterus scutellatus Gyllenhal, Blue gum psyllid, Ctenarytaina eucalypti, red gum lerp psyllid, Glycaspis brimblecombei.  Thus far these insects primarily kill temperate zone eucalyptus trees.  The more tropical eucalyptus species that produce a copious amount of resinous substances under the bark, appear to be relatively immune to successful attack.  Efforts to secure natural enemies of these pests were initiated at the University of California, Riverside.  Natural enemies of the beetles that are considered as candidates for dissemination are an egg parasitoid, Avetianella longoi, and the ichneumonid, Helcostizus rufiscutum Cushman.  The parasitoid Patasson nitens (Girault) was imported from South Africa to combat Eucalyptus Snout Beetle.  Based on the earlier success of this parasitoid in South Africa  (see <ch-42.htm>), biological control would be expected to be successful in California.  However, the work on other pests s in progress and too new to report definite results, although at least one species of parasitic Hymenoptera appears to be established.  As of March 2001, many of the eucalyptus species that were originally introduced from Tasmania and southern portions of the Australian continent are in the final stages of mortality.  The eucalyptus species originating from more tropical latitudes have thus far survived quite well, probably due to their ability to secrete more copious resin.  The picture becomes more uncertain as new species of invaded psyllids  reduce the vigor of these trees.



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


Dahlsten, D. L., E. P. Hansen, R. L. Zuparka & R. B. Norgaard.  1998a.  Biological control of the blue gum psyllid proves economically beneficial.  Calif. Agric. 52(1):  35-40.


Dahlsten, D. L., D. L. Rowney, W. A. Copper, et al.  1998b.  Parasitoid wasp controls blue gum psyllid.  Calif. Agric. 52(1): 31-34.


Hanks, L. M., J. G. Millar and T. D. Paine.  1995.  Biological constraints on host range expansion by the wood-boring beetle Phoracantha semipunctata F. (Coleoptera: Cerambycidae).  Ann. Entomol. Soc. Am.  88: 183-188.


Hanks, L. M., J. R. Gould, T. D. Paine, J. G. Millar and Q. Wang.  1995.  Biology and host relations of Avetianella longoi, an egg parasitoid of the Eucalyptus longhorned borer.  Annals Ent. Soc. Am. 88: 666-671.


Hanks, L. M., T. D. Paine, J. G. Millar and J. L. Hom.  1994. Variation among Eucalyptus species in resistance to eucalyptus longhorned borer in southern California.  Entomol. exp. appl.  74:185-194.


Hanks, L.M., J.G. Millar, and T.D. Paine.  1997.  Host range expansion of Helcostizus rufiscutum Cushman (Hymenoptera: Ichneumonidae) to include Phoracantha semipunctata F. (Coleoptera: Cerambycidae) in California. Pan-Pac. Entomol., 73: 190-191.


Hanks, L.M., T.D. Paine, and J.G. Millar.  1996.  A tiny wasp comes to the aid of California's Eucalyptus trees.  Calif. Agric. 50 (May-June):  14-16.


Paine, T. D., J. G. Millar and L. M. Hanks.  1995.  Biology of the Eucalyptus longhorned borer in California and development of an integrated management program for the urban forest.  Calif. Agric.  49 (Jan.-Feb.):34-37


Paine, T.D., J.G. Millar, T.S. Bellows, and L.M. Hanks.  1997. Enlisting an under-appreciated clientele: public participation in distribution and evaluation of natural enemies in urban landscapes. American Entomologist 43: 163-172.


Paine, T. D., D. L. Dahlsten, J. G. Millar, M. S. Hoddle & L. M. Hanks.  2000.  UC scientists apply IPM techniques to new eucalyptus pests.  Calif. Agric. 54(6):  8-13.


Scriven, G. T., E. L. Reeves & R. F. Luck.  1986.  Beetle from Australia threatens eucalyptus.  Calif. Agric. 40(4):  4-6.