The Red Gum Lerp Psyllid in California

Background

The red gum lerp psyllid, Glycaspis brimblecombei (Homoptera: Psylloidea; Spondyliaspididae) has recently been discovered and it is the first lerp psyllid to make its way from Australia to California. It is apparently a new North American record (CPPDR,1998). It was discovered on red gum Eucalyptus in Los Angeles County in June of 1998 along a freeway in El Monte and several of the trees were heavily infested. The psyllid was identified by Ray Gill of the Calif. Dept of Food and Agriculture and the identification confirmed by Daniel Burckhardt, a Swiss psyllid specialist. It was found in Northern California on 24 July, 1998 at the Ardenwood Farm East Bay Regional Park, Fremont. Since that time it has also been found on the Stanford campus in Palo Alto and at many other locations in the South and East Bay. We have received many calls from Extension specialists and arborists in the Bay Area as to what can be done.

Counties where infestations have been observed as of 1 June, 2000 include, Alameda, Butte, Contra Costa, Colusa, Fresno, Glenn, Inyo, Kings, Kern, Los Angeles, Marin, Madera, Mariposa, Merced, Monterey, Napa, Orange, Placer, Riverside, Santa Clara, San Bernardino, San Mateo, San Diego, Santa Barbara, Sacramento, Santa Cruz, San Benito, San Joaquin, Shasta, Sutter, Stanislaus, Solano, Sonoma, Tehema, Tulare,Ventura, Yolo, and Yuba.

Some of the Eucalyptus species have been heavily attacked and this has resulted in heavy leaf drop. In addition, the psyllid produces large amounts of honeydew. This results in blackened foliage due to sooty mold. These psyllids form a lerp, which is a secretionary structure produced by the nymphs as a protective cover. 'Lerp' is a term derived from an aboriginal Australian language describing this cover. There are eight host species of Eucalyptus known in Australia including E. camaldulensis (=E. rostrata) (river red gum), E. blakelyi (Blakely’s red gum), E. nitens (shining gum or silver top), E. tereticornis (forest red gum), E. dealbata (tumbledown red gum), E. bridgesiana (apple box), E. brassiana (Cape York red gum), and E. mannifera (Brittle gum) (Moore, 1970, Morgan 1984, McCarver, 1987). To date the psyllid has been recorded on these species in California: E. camaldulensis (=E. rostrata), E. rudis, E. globulus, E. deiversicolor, and E. sideroxylon.

The immediate response of the pest control community has been to look for a chemical pesticide, but the efficacy is unknown and no one in the California has any experience with this insect. Based on the number of infestations in many areas of the state this could result in the heavy use of chemical sprays in those urban areas where red gums are commonly used as ornamentals. The development first of a monitoring program and then a biological control program would reduce the pesticide load in the environment. Both of these activities are socially acceptable, and as we have found with the elm leaf beetle project (Dahlsten et al. 1998) monitoring alone can reduce the use of pesticides. If the program is as successful as the recent blue gum psyllid project, no pesticides will be necessary (Dahlsten et al. 1998).

In this project we will be working with the East Bay Regional Parks (Nancy Brownfield), the Stanford Univ. Grounds Dept. (Herb Fong and Carol Sweetapple), the City of Los Angeles, and other agencies to develop and implement the biological control program. The Cooperative Extension Specialists and Farm Advisors will also assist with this task. The University of California's College of Natural Resources at Berkeley and the Statewide Integrated Pest Management Program is providing funding.

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