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Project description

Biology and ecology of Psyllaephagus spp. parasitic on the redgum lerp psyllid, Glycaspis brimblecombei Moore. (01XU034)
Program Exotic Pests and Diseases Research Program
Principal
investigators 		K.M. Daane, Insect Biology, UC Berkeley
D.L. Dahlsten, Insect Biology, UC Berkeley
Host/habitat Eucalyptus
Pest Redgum Lerp Psyllid Glycaspis brimblecombei
Discipline Entomology
Review
panel 		Urban Systems
 Start year (duration)  2001 (Two Years)
Objectives Investigate the biology of Psyllaephagus species parasitic on the redgum lerp psyllid, Glycaspis brimblecombei.

Improve mass-rearing for Psyllaephagus species to facilitate parasitoid distribution throughout infested regions of California.

Second-year
progress 		The red gum lerp psyllid (RGLP) was discovered in 1998 on red gum eucalyptus in Los Angeles and Alameda counties. It has since spread throughout the state to every county where eucalyptus trees are found and has caused considerable damage and even death of infested red gum trees. Already, thousands of dead trees have already been removed in southern California, at a considerable cost. To improve biological control, parasitic wasps that attack RGLP were imported from areas near Sydney, Melbourne, and Adelaide (Australia). One species (Psyllaephagus bliteus) was selected for release throughout California. To facilitate the mass production and statewide release and establishment of P. bliteus, laboratory and field studies are begin conducted to determine P. bliteus longevity, fecundity, host stage preference, host feeding and temperature development. Results show that P. bliteus prefers to oviposit in third instar psyllid nymphs, although the parasitized psyllid does not form a "mummy" until the RGLP's fifth and final instar. The parasitoid can oviposit in all five nymphal stages of the psyllid, and will commonly host feed (killing and feeding on the psyllid without placing an egg inside the host) on first and second instar psyllids. Laboratory studies show RGLP development is a positive function of temperature at 22, 25 and 30ºC. However, at 30ºC there was considerable mortality and at 35ºC, no RGLP developed from egg to adult. The most rapid development occurred with mixed daily temperatures of 30º and 25ºC (16:8 hrs, respectively). Other ongoing laboratory and field experiments are investigating parasitoid development under different field temperatures in coastal and interior portions of the state. The developed information has improved insectary operations and will aid parasitoid release and establishment efforts.

First-year
progress 		The redgum lerp psyllid was discovered in 1998 on red gum eucalyptus in Los Angeles and Alameda counties. It has since spread throughout the state to every county where eucalyptus trees are found and has caused considerable damage and even death of infested trees. Already, thousands of dead trees have been removed in southern California at a considerable cost. To improve biological control, parasitic wasps that attack the red gum lerp psyllid were imported from areas near Sydney, Melbourne, and Adelaide (Australia). One species (Psyllaephagus bliteus) was selected for release throughout California. To facilitate the mass production and statewide release of P. bliteus, we have begun laboratory and field studies of P. bliteus biology. Information on parasitoid longevity, fecundity, host-stage preference, and host-feeding levels are being collected. Initial results found P. bliteus prefers to oviposit in third instar psyllid nymphs, although the parasitized psyllid does not form a "mummy" until the psyllid's fifth and final instar. The parasitoid can oviposit in fourth and, possibly fifth instar psyllids and will host feed (killing and feeding on the psyllid without placing an egg inside the host) on first and second instar psyllids. This information has improved insectary operations. Other ongoing laboratory and field experiments are investigating parasitoid development under different constant and field temperatures, and parasitoid host feeding requirements.

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