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 The elm leaf
beetle became widely spread in the United States after its invasion from
Europe in the 1830's (Howard 1908, Clausen 1956, Dahlsten & Hall
1999). It was first detected on elms
in Baltimore, Maryland, in 1838-1839 and then spread throughout most of the
continental United States and parts of Canada. The beetlei entered California around 1924 where it defoliated
elms in Fresno
Adult
beetles and their larvae feed on elm foliage, although the larvae do most
damage. Adult feeding damage consists
of small round holes in the leaves while larvae skelotonize the underside of
leaves. The larval feeding causes
leaves to turn brown and eventually fall from the tree. Damage is greater on English elms (Ulmus procera) and Scotch elm (Ulmus glabra) than on Siberian elms (Ulmus
pumila), while Chinese elm (Ulmus
parvifolia) receives little to no damage. Loss of foliage is an aesthetic problem as
well as a functional one since trees no longer provide shade. Repeated defoliation may weaken trees and
increase susceptibility to diseases such as Dutch elm disease (Ophiostoma ulmi). In California, an estimated 2.5 million
elms have been planted and ELB is the most commonly treated pest on those
elms. Municipalities and individual homeowners
often treat with either foliar or systemic insecticides.
Biological control attempts involved introductions of the eulophid egg
parasitoid, Tetrastichus
gallerucae (Fonscolmbe)
(= Tetrastichus xanthomelaenae Rondani) were made
from Europe and the Middle East (Berry 1938b, Clair et al. 1988), and it
became established in Ohio in 1932 (Hall & Johnson 1983). Elm leaf beetle seems to be controlled by T. gallerucae, preventing high levels of defoliation, and
the project in Ohio was judged to be partially to substantially successful
(Dahlsten & Hall 1999). Erynniopsis antennata Rondani was introduced and
established in Central California from Europe in 1939 (Flanders 1941). Tetrastichus gallerucae was also introduced and
recovered in northern and southern California (Luck & Scriven 1976, Clair
et al. 1988). However, overwintering
decimates the parasitoid in California such that early season parasitization
rates are very low. Tetrastichus brevistigma Gahan, apparently native
to the northeastern United States, was reported parasitizing 50-80% of beetle
pupae in that area (Berry 1938b).
This parasitoid has also been established in California but appears to
exert little control on beetle populations (Luck & Scriven 1976). A more recent appraisal of its performance
in Ohio suggest that it is no longer important there either (Dahlsten &
Hall 1999). Luck & Scriven (1976)
reported that E. antennata parasitism significant
late in the season in California, but they did not consider the activity of
both species of parasitoids sufficient to prevent significant damage.
For greater details of natural enemies and biological control efforts
against the elm leaf beetle, please see the following (Silvestri 1904, 1910;
Marchal 1905, Provasoli 1932, Flanders 1936, 1941; Clausen 1956, Dowden
1962).
REFERENCES:
Berry, P. A.
1938a. Laboratory studies on Tetrastichus xanthomelaenae Rand. and Tetrastichus sp., two hymenopterous
egg parasites of the elm leaf beetle.
J. Agric. Res. 57: 859-63.
Berry, P. A. 1983b. Tetrastichus brevistigma Gahan, a pupal parasite
of the elm leaf beetle. USDA Cir
485. 11 p.
Clair, D. J., D. L. Dahlsten & S.
H. Dreistadt. 1988. Biological control of the elm leaf beetle,
Xanthogaleruca luteola, in California--A case
study. Proc. 6th Intern. Conf. of
Intern. Fed. Organic Agric. Movements, 20 Aug 1986, Santa Cruz, California.
Clair, D. J., D. L. Dahlsten & E. R. Hart. 1987.
Rearing Tetrastichus
gallerucae (Hymenoptera:
Eulophidae) for biological control of the elm leaf beetle, Xanthogaleruca luteola. Entomophaga 32:
457-61.
Clausen, C. P. 1956. Biological control of insect pests in the
continental United States. U. S.
Dept. Agric. Tech. Bull. 1139. 151 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
Dowden, P. B.
1962. Parasites and predators
of forest insects liberated in the United States through 1960. U. S. Dept. Agric. Agric. Handbk.
226. 70 p.
Flanders, S. E. 1936. Japanese species of Tetrastichus parasitic on eggs of Galerucella xanthomelaena (Schrank). J. Econ. Ent. 29: 1024-1025.
Flanders, S. E. 1941. Observations on the biology of the elm
leaf beetle parasite, Erynnia
nitida (R.Desv.). J. Econ. Ent. 33: 947-948.
Hall, R. W. & N. F. Johnson. 1983.
Recovery of Tetrastichus
gallerucae (Hymenoptera:
Eulophidae), an introduced egg parasitoid of the elm leaf beetle (Pyrrhalta luteola) (Coleoptera:
Chrysomelidae). J. Kan. Ent. Soc.
56: 297-298.
Hilker, Monika
& Nina F. Fatouros. 2015.
Plant Responses to Insect Egg Deposition. Ann. Rev. Entomol. 60 (1):
493–515.
Howard, L. O.
1908. The importation of Tetrastichus xanthomelaenae (Rond.). J. Econ. Ent. 1: 281-89.
Luck, R. F. & G. T. Scriven. 1976.
The elm leaf beetle, Pyrrhalta
luteola in southern
California: its pattern of increase
and its control by introduced parasites.
Environ. Entomology 5: 409-416.
Marchal, P. 1905.
Observations biologiques sur un parasite de la galeruque de l'orme (le
Tetrastichus xanthomelaenae). Bull. Ent. Soc. France (1905): 64-68.
Meiners,
T. & M. Hilker. 1997. Host location in Oomyzus gallerucae
(Hymenoptera: Eulophidae), an egg parasitoid of the elm leaf beetle
Xanthogalereuca luteola (Coleoptera: Chrysomelidae). Oecologia, Vol. 112, No. 1 / Sept. 1997, pp 87-93. Springer Berlin / Heidelberg. ISSN 0029-8549:
1432-1939.
Provasoli, L. 1932. Contributo alla biologia ed
all'embriologia della Galerucella
luteola (F. Muller) e
del suo endofago Tetrastichus
xanthomelaenae
(Rond.). Bol. Lab. Zool. Milano
3: 53-66.
Silvestri, F. 1904.
Contribuzione alla conoscenze della matamorfosi e dei costumi della Lebia scapularis Fourc.
Redia 2: 68-84.
Silvestri, F. 1910.
Contribuzioni alla conoscenza degli insetti dannosi e dei loro
simbionti. I. Galerucella
dell'olmo (Galerucella luteola F. Mull.). Bol. Lab. Zool. Gen. Agric., Portici 4: 246-88.
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