Avetianella longoi
 Parasitic Wasp of the Eucalyptus longhorned Beetle (ELB)

Photography by Max E. Badgley (1922-2006)

Avetianella longoi, a native of Australia, parasitizes the eggs of the eucalyptus long-horned borer, Phoracantha semipunctata.  The eucalyptus longhorned borer (ELB) is also a native of Australia, but is now found throughout the Mediterranean coast, having been introduced there by seafaring traders.  ELB arrived in the United States, in the state of California, sometime prior to 1984.  It now poses a serious threat to eucalyptus trees throughout the western U.S.  Those trees are used as ornamentals, windbreaks and for pulpwood and firewood. In the absence of natural enemies, ELB soon killed eucalyptus trees by the thousands.

Entomologists at the University of California/Riverside researched the natural enemies of ELB in Australia and learned that Avetianella longoi, a minute, black wasp, is unusually adapted to parasitize ELB eggs.  Clusters of these eggs are deposited under loose shards of shaggy-barked species of eucalyptus (smooth barked species provide no such haven), where they are not easily reached by other predatory insects. Adult A. longoi females have a flat profile that lets them negotiate the loose bark, where they search for, and deposit their eggs into, ELB eggs. A single female wasp, in a month's time, parasitizes an average of 200 ELB eggs, and as many as 5 wasps successfully develop in each parasitized ELB egg.

Armed with this information, UCR imported A. longoi to the U.S. in 1992, established a rearing lab for them, and released the first batch of naturalized A. longoi wasps in 1993.  The wasps spread to all areas infested with ELB, with devastating effect on ELB populations.  All evidence collected to date indicates this parasitoid will succeed in exercising significant control over ELB in the U.S.

Text compiled and edited by J.Cates,  curator

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