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Project description

Biological Control of a Newly Introduced Pest, the Eucalyptus Tortoise Beetle, Trachymela sloanei. (99CC014)
Program UC IPM competitive research grants program
J.G. Millar, Entomology, UC Riverside
T.D. Paine, Entomology, UC Riverside
M.S. Hoddle, Entomology, UC Riverside
Host/habitat Landscape Trees and Shrubs; Eucalyptus
Pest Eucalyptus Tortoise Beetle Trachymela sloanei
Discipline Entomology
Enoggera reticulata
Cultural Controls
Start year (duration)  1999 (Two Years)
Objectives Develop and implement a biological control program targeting a recently introduced pest, the eucalyptus tortoise beetle, using a highly specific and well-studied pteromalid egg parasitoid, Enoggera reticulata.
Final report The eucalyptus tortoise beetle, Trachymela sloanei, was accidentally introduced into California from Australia about four years ago. In the absence of its natural enemies, populations of the beetle increased and spread rapidly. It is now distributed throughout southern California. Both the beetle and its larvae feed on eucalyptus foliage, and heavy populations can rapidly defoliate trees. In an effort to establish a control program for the beetle, we brought in a small pteromalid wasp, Enoggera reticulata, that parasitizes the eggs of the beetle. The wasp proved difficult to rear, but during the two-year period of the project, we were able to rear and release more than 4,000 wasps in four southern California counties. We also established sampling plans to quantify tortoise beetle damage to eucalyptus trees, to estimate beetle population densities, and to search for evidence that the parasitoid had successfully established breeding populations at one or more of the release sites. To date, there are indications that the wasp may be established and killing tortoise beetle eggs at one or more release sites, but we cannot be certain because we have not yet recovered any beetle eggs that contained developing parasites from any of our field sites. Furthermore, our sampling efforts have been hindered by the extensive damage caused by the redgum lerp psyllid, which has defoliated and killed many trees throughout southern California.

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