|Title||Imported parasitic wasp helps control red gum lerp psyllid|
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|Abstract||The red gum lerp psyllid is an insect native to Australia, where it feeds upon eucalyptus species. Since 1998 this psyllid has spread throughout California, resulting in millions of dollars in damage and control costs. To help suppress the red gum lerp psyllid, a biological control program was initiated and a psyllid-specific parasitic wasp was imported from Australia in 1999 and released in 2000. In most coastal regions this biological control agent has provided substantial control, but in some interior regions the psyllid still remains a problem. Researchers are continuing their investigations to determine if full statewide suppression will be realized eventually, or if further importation of new parasitoid species is needed.|
Bianchi, Mary L
County Director and Horticulture Farm Advisor
Horticulture, pomology, subtropicals, water management and water quality. Horticulture in San Luis Obispo County and Northern Santa Barbara County.
Chaney, Ph.D., William E
Farm Advisor Entomology (Emeritus, Retired)
Daane, Kent M
Biological control and IPM of insect pests in perennial crops (almond, grape, stone fruit, olives, pistachios), annual crops (lettuce) and ornamentals (eucalyptus, ornamental).
Dahlsten, Donald L. :
Geisel, Pamela M.
UC Cooperative Extension Advisor, emeritus
Tree crops, grapes and strawberries, environmental horticulture, and Master Gardeners/urban horticulture. Areas of research and extension focus include IPM, evaluation of sustainable products and practices, water conservation and deficit irrigation, home orchards and vineyards, sustainable landscaping, alternative turfgrass species, and tree training, pruning, and grafting.
John, Andrews W. : J.W. Andrews Jr. is Staff Research Associate, Division of Insect Biology, UC Berkeley
Kabashima, John N.
Environmental Horticulture Advisor, Emeritus
Ornamental horticulture, nursery crops, pest management, exotic and invasive pests, water runoff, water quality
Lawson, Andrew B. : A.B. Lawson was Postdoctorate Researcher (currently Assistant Professor, California State University, Fresno)
Paine, Timothy D
Entomologist and Professor
Integrated pest management of insects affecting nursery stock, woody ornamental or landscape plants, and trees in urban or recreational forests; ecological interactions between environmental stress on plants and insect herbivores; chemical ecology; insect-microorganism-plant interactions; biological control
Robb, Karen L.
Farm Advisor County Director
Horticulture, Entomology and Integrated Pest Management, Ag/Urban Issues
Roltsch, William J. : W.J. Roltsch is Associate Environmental Research Scientist, California Department of Food and Agriculture
Rowney, David L. : D.L. Rowney is Statistician
Shaw, David A.
Turfgrass, Landscape, Arboriculture, Irrigation Management
Sime, Karen R. : K.R. Sime is Postdoctorate Researcher
Taylor, Gary : We thank the UC Exotic Pests and Diseases Research Program, UC Statewide Integrated Pest Management Program, Action Mulch, Disney Corp., East Bay Regional Park District, Los Angeles Zoo, Rancho Santa Fe Association, Stanford University Buildings and Grounds Department, and agencies in the cities of Huntington Beach, Los Angeles, Torrance and Redwood City for funding. We thank Mike Keller, Kerrie Davies and John Jennings of the University of Adelaide, Waite Campus, and Christine Stone of the State Forests of New South Wales facility in the Cumberland State Forest for help with foreign exploration. We thank Larry Costello, David Haviland, Daniel Sullivan, Rod Sime and Marta Yamamoto for laboratory or field assistance.
Varela Dr, Lucia G.
North Coast IPM Advisor
Apples, pears, wine grapes, pest management
|Publication Date||Oct 1, 2005|
|Date Added||May 12, 2009|
|Copyright||© The Regents of the University of California|
Classical biological control was employed for a eucalyptus pest; the parasitoid was more effective in coastal than interior regions.
RESEARCH ARTICLE t Imported parasitic wasp helps control red gum lerp psyllid Donald L . Dahlsten Kent M . Daane Timothy D . Paine Karen R . Sime Andrew B . Lawson David L . Rowney William J . Roltsch John W . Andrews Jr . John N . Kabashima David A . Shaw Karen L . Robb Pamela M . Geisel William E . Chaney Chuck A . Ingels Lucia G . Varela The parasitoid Psyllaphaegus bliteus has been released throughout California to Mary L . Bianchi control the red gum lerp psyllid , a pest of Gary Taylor eucalyptus . Above , an adult P . bliteus uses t its ovipositor to place an egg inside the red gum lerp psyllid nymph . The parasitoid develops inside the psyllid nymph , which typically does not show any signs of parasit - years ago . Until recently , eucalyptus ism until the nymph reaches the fifth instar , The red gum lerp psyllid is an insect when the parasitoid pupa â?? far left , white trees in California were relatively free native to Australia , where it feeds body , and left , dark body â?? can be seen from damaging insect pests . Most of through the mummified psyllid . upon eucalyptus species . Since 1998 Californiaâ??s native insects cannot feed this psyllid has spread throughout on eucalyptus , which is well protected California , resulting in millions of from herbivores by chemicals such as dollars in damage and control costs . distasteful essential oils ( which are fa - first found on river red gum in June miliar to anyone who has smelled the 1998 in Los Angeles County and had To help suppress the red gum lerp strong odor of the leaves ) . The Austra - spread throughout the state by 2000 , psyllid , a biological control program lian insects that have adapted to feed and throughout Mexico and parts of was initiated and a psyllid - specific on eucalyptus were not transported to Florida by 2002 . In Australia there are a parasitic wasp was imported from California with earlier shipments of number of eucalyptus species that the Australia in 1999 and released in plant propagation material , usually red gum lerp psyllid can feed on , but in 2000 . In most coastal regions this in the form of seeds . This began to California the only favored eucalyptus biological control agent has provided change in the early 1980s and at least species present is the river red gum ; substantial control , but in some inte - 15 eucalyptus - feeding insect species the forest red gum ( E . tereticornis ) and from Australia were accidentally intro - flooded gum ( E . rudis ) , both also in rior regions the psyllid still remains a duced and are now established in Cali - California , are less - favored trees that the problem . Researchers are continuing fornia ( Paine and Millar 2002 ) . While psyllid can feed on as well . their investigations to determine if eucalyptus trees may be unwanted in Red gum lerp psyllid nymphs build full statewide suppression will be some areas because they crowd out na - white conical shelters called lerps from realized eventually , or if further im - tive vegetation , their extensive value in excreted honeydew and waxes , and portation of new parasitoid species is many other locations led to efforts to live underneath these structures . The needed . control the psyllid . nymphs feed by sucking plant sap from River red gum ( Eucalyptus camal - leaves . The accumulation of the sticky dulensis ) is among the most com - ucalyptus trees and shrubs , valued lerps and honeydew on leaves and monly planted shade and windbreak Efor their ability to flourish in arid under infested trees creates a nuisance , trees in California and is also grown regions and their varied horticultural while heavy infestations lead to defolia - commercially for fuel wood and fi - uses , have been a familiar feature of tion , branch dieback and occasionally ber ( Cockerham 2004 ) . The red gum Californiaâ??s urban and rural landscapes tree death ( Paine et al . 2000 ) . lerp psyllid ( Glycaspsis brimblecombei since they were first introduced from The first attempts to control red Moore ; Hemiptera : Psylloidea ) was their native Australia more than 150 gum lerp psyllid focused on the use of http : / / CaliforniaAgriculture.ucop.edu â?¢ OctOber â?? December 2005 229 t Below , life stages of the red gum lerp psyllid include , ( left to right ) large nymph , row of eggs , winged adult and small lerp ( the protective covering produced by nymphs ) . Clark Kelly Jack t Clockwise from top left : Karen Sime , UC Berkeley postdoctorate researcher , checks a caged eucalyptus leaf Clark for evidence of P . bliteus activity and parasitism rates ; the late Don Dahlsten ( first author ) was a leading UC Kelly researcher ( 1966 â?? 2003 ) in biological control of urban and Jack forest pests ( shown in 1974 ) ; small discs coated with a light oil were used to capture and sample populations of adult red gum lerp psyllid and P . bliteus ; red gum lerp psyllids feed on eucalyptus leaves , building up to such high densities that the accumulation of psyllids and honeydew causes sooty molds , defoliation and even tree death ; in the San Joaquin Valley ( Tulare County ) , a dead red gum eucalyptus ( left ) near an undamaged and uninfested blue gum eucalyptus ( right ) demonstrates the psyllidâ??s feeding preferences . systemic insecticides , mainly to target ulation dynamics throughout the state . Classical biological control appeared , heavy infestations on particularly valu - We therefore investigated whether red therefore , to be the most promising able trees . The proper timing of treat - gum lerp psyllid populations could approach for controlling the red gum ments was difficult to determine and be tracked with sticky traps , which lerp psyllid . We report here on a large control was not always achieved ( Paine had been used for the blue gum and collaborative effort between UC , the et al . 2000 ) . The obvious impracticality eugenia psyllid programs ( Dahlsten et California Department of Food and of using insecticide treatments on trees al . 1998 ) . The traps consisted of trans - Agriculture ( CDFA ) and research scien - throughout the state led us to investi - parent 4 - inch ( 10 - centimeter ) plastic tists in Australia . gate more sustainable options . We first disks coated with a thin layer of motor Prerelease psyllid sampling investigated whether any predators oil additive and clipped over a yellow already present in California could pro - backing . At each site , 10 to 12 traps Before the biological control program vide control . Lady beetles ( Hippodamia ) , were hung in eucalyptus trees and began , we gathered detailed information green lacewings ( Chrysoperla ) , minute changed weekly . about red gum lerp psyllid populations pirate bugs ( Orius ) and syrphid flies In 1999 and 2000 , we tested trap ac - throughout California . Beginning in July feed on adult and immature red gum curacy at two sites , one in Northern 1999 , sample sites were established in lerp psyllids ( Erbilgin et al . 2004 ) . California ( Alameda County ) and Alameda , Santa Clara , Monterey , Los However , even when present in large the other in Southern California ( Los Angeles and San Diego counties . By July numbers , these predators did not pro - Angeles County ) . Near each trap at 2002 , we had established 32 sample sites , vide adequate control . these sites , two 12 - inch ( 30 - centimeter ) with at least one site located in every In Australia , red gum lerp psyllid foliage samples were collected every California county in which red gum lerp populations are held in check in large 3 weeks ( 20 to 24 samples per site per psyllid had been reported . part by species of parasitic wasps that sample date ) . We found a good cor - Sampling psyllid populations ac - specifically attack them and their close relation between the mean number of curately can be difficult . The most adult female psyllids per sticky trap relatives . Other parasitoid species im - accurate way of measuring densities and the mean number of psyllid eggs ported from Australia had successfully and damage levels is to count psyllid 2 = 0.82 ; per leaf sample ( P < 0.01 , r controlled earlier outbreaks of other nymphs on leaves . This method , how - Paine et al . [ 2000 ] ) , indicating that the introduced Australian psyllid species ever , is time - consuming and impracti - sticky - trap counts provided a good es - in California , including the blue gum cal for the large number of sample sites timate of psyllid activity in eucalyptus . psyllid ( Dahlsten et al . 1998 ) and the and frequent sampling dates needed to Thereafter , we relied exclusively on the eugenia psyllid ( Dahlsten et al . 1995 ) . follow psyllid and natural - enemy pop - 230 CALIFORNIA AGRICULTURE â?¢ VOLUME 59 , NUMBER 4 Fig . 1 . P . bliteus oviposition success in different host develop - mental stages , as indicated by the percentage egg deposition ( Â± SEM ) of parasitized red gum lerp psyllids , was significantly different ( F = 12.48 , df = 4,25 , P < 0.001 ) . Above each bar , Fig . 2 . P . bliteus lifetime fecundity under glasshouse conditions , as means followed by different letters are significantly different estimated by egg deposition with an overabundant host supply . ( Tukeyâ??s HSD test , P < 0.05 ) . Source : Daane et al . ( 2005 ) . Source : Daane et al . ( 2005 ) . sticky - trap technique to monitor the for oviposition , the parasite larvae did culture and was selected for release psyllids . In addition , we used the same not fully develop until after the host after experiments showed that it specifi - traps to monitor parasitoid populations reached the fifth ( last ) instar . In addi - cally attacked the red gum lerp psyllid after we began releasing them . tion , adult female wasps also occasion - when tested against three other psyllid Initially , we counted both male and ally killed psyllid nymphs by host species ( Eugenia , blue gum and mela - i - female adult psyllids per trap by sample feeding , stabbing them with their ov leuca ) ( Paine et al . 2000 ) . Parasitoid biology . To facilitate in - positors and drinking the body fluids week . However , we noticed strong sectary rearing and field release , we leaking out from under the lerp . Usually seasonal changes in the relative propor - collected basic biological information younger nymphs are attacked but we tions of adult females and males . For on P . bliteus ( Daane et al . 2005 ) . First , observed this host feeding on all stages . example , female psyllids typically had Longevity and fecundity . Adult we determined which stages of the host the highest populations in the summer P . bliteus longevity and fecundity were ( red gum lerp psyllid ) were preferred months and dropped significantly the also determined . Newly emerged and by the female parasitoids ( P . bliteus ) for rest of the year . Because their numbers mated female P . bliteus were individu - oviposition . Potted eucalyptus trees were are most closely associated with egg - ally isolated in clear plastic tubes that infested with 300 to 500 psyllid nymphs , laying ( and thus nymphal activity and each enclosed a single infested leaf with the population composed of all five damage ) , we plotted only the adult on a potted river red gum tree in the nymphal stages in similar proportions , female psyllids caught on the traps . At glasshouse ( 71.6 Â± 3 Â° F ) . Each leaf was and isolated in organdy sleeve cages each monitoring site , we reported the infested with 10 to 30 psyllids , mostly with 15 to 20 adult female P . bliteus . After averages of 10 to 12 traps . third instars . Each female P . bliteus was 24 hours , all psyllids were collected and Finding , importing parasitoids transferred to a new leaf every 2 days cleared in chloralphenol , which makes throughout her lifetime . After each any P . bliteus eggs inside the psyllid To find promising parasitoids , transfer , the parasitoid - exposed psyllids body visible under a dissecting micro - mummified red gum lerp psyllids were cleared in chloralphenol , and the scope . The number of eggs and the psyl - were field - collected and shipped from presence of P . bliteus eggs was recorded . lid stages were recorded . We also used southern Australia to the UC Berkeley Under these conditions , we found that similar methods to investigate P . bliteus Quarantine Facility in August 1999 ( the average female P . bliteus longevity was larval development . â?? mummified â?쳌 psyllid is visibly dead , 60.4 Â± 6.4 days and average lifetime We collected the psyllids every 3 to killed by the internal parasitoid that egg deposition was 125.7 Â± 24.6 eggs 4 days after exposure to female wasps , is nearing completion of its develop - per female ( range 34 to 302 ) . Most eggs cleared them in chloralphenol , and ment ) . This region , near Adelaide , has ( 88.1 % ) were deposited during the ini - then recorded both the presence of P . a Mediterranean climate , with tempera - tial 22 days , although one parasitoid bliteus eggs or larvae and the develop - tures similar to Californiaâ??s coastal re - deposited eggs up to 70 days after emer - mental stages of parasitized psyllids . gions . From the field - collected psyllids , gence ( fig . 2 ) . There were five host preference and we reared eight species of parasitoids in These results have implications for four larval development replicates ; the the genus Psyllaephagus ( Hymenoptera : insectary operations and release strate - treatment means were separated using Encyrtidae ) . Of these , two were hy - gies in classical biological control pro - Tukeyâ??s HSD test . Our results showed perparasitoids ( which attacked the grams . Although adults may survive that P . bliteus can oviposit into psyllid beneficial â?? primary â?쳌 parasitoids ) that for long periods , most egg deposition nymphs of any age , but that they usu - attacked the other Psyllaephagus species , occurs early in the adultâ??s lifetime . ally parasitize third and fourth instars and most others failed to propagate in Insectary colonies should therefore be ( fig . 1 ) . In our studies , regardless of the the insectary . The remaining species supplied with the needed number of stage of the host exposed to P . bliteus ( Psyllaephagus bliteus Riek ) did well in http : / / CaliforniaAgriculture.ucop.edu â?¢ OctOber â?? December 2005 231 TABLE 1 . P . bliteus releases by California county , 2000 to 2003 , show the widespread collaborative effort to release and establish the imported red gum lerp psyllid parasitoid County Sites Releases Release period Released no . no . no . Alameda 2 5 June 2000 â?? Aug 2001 571 Amador 1 2 Aug 2002 802 Butte 1 1 July 2002 735 Calaveras 1 1 June 2002 1,047 Colusa 1 1 July 2002 408 Contra Costa 1 1 May 2002 654 Fresno 1 2 Nov 2000 , Aug 2001 473 Glenn 1 1 Sep 2001 569 Imperial 2 1 June 2002 998 Kern 1 1 July 2002 245 Kings 1 1 May 2002 522 Lake 1 1 Sep 2002 625 Los Angeles 8 15 June 2000 â?? June 2002 4,016 Madera 1 1 June 2002 752 Marin 1 1 May 2002 571 Mariposa 2 2 Aug 2002 , Jan 2003 728 Merced 1 1 Nov 2001 933 Monterey 2 2 Dec 2000 , Sep 2001 518 Napa 1 1 Apr 2002 650 Orange 3 4 Nov 2000 , Dec 2001 1,846 Placer 2 2 July , Sep 2002 1,514 Riverside 6 7 Nov 2001 â?? Mar 2002 3,910 Sacramento 4 8 Oct 2000 â?? June 2002 3,070 San Benito 1 1 Aug 2002 587 San Bernardino 5 5 Oct 2001 â?? Mar 2002 3,775 San Diego 3 8 Sep 2000 â?? May 2002 1,914 San Joaquin 2 2 Apr , Sep 2002 1,070 San Luis Obispo 1 3 Sep 2001 â?? Jan 2002 2,863 Santa Barbara 2 2 Feb , July 2001 217 Santa Clara 2 1 Sep 2000 50 Santa Cruz 1 1 Aug 2002 610 Shasta 3 2 June 2002 2,002 Solano 1 2 Sep 2001 , July 2002 1,405 Sonoma 1 2 Sep , Oct 2001 1,309 Stanislaus 1 1 May 2002 836 Sutter 2 2 May , June 2002 1,465 Tehama 2 2 Oct 2000 , June 2002 1,048 Tuolumne 2 2 Aug , Oct 2002 875 Tulare 1 1 June 2002 800 Ventura 1 1 Sep 2000 71 Yolo 1 1 June 2002 573 Fig . 3 . Red gum lerp psyllid adult females and P . bliteus parasitoid Yuba 1 1 June 2002 955 adults ( both mean per trap per week ) and parasitoid release dates in a single site each in ( A ) eastern Los Angeles County , ( B ) San Mateo Totals : 78 102 48,582 County ( parasitoids originally released in nearby counties ) and ( C ) southern Sacramento County . June 2000 in Los Angeles and Alameda third - or fourth - instar psyllids for an Angeles County is an example of a site counties . Between September 2000 and oviposition period of 2 to 3 weeks . In with a marked decrease in psyllids and January 2003 , we released a total of addition , first or second instars should an increase in parasitoids ( fig . 3A ) . Peak 48,582 adults in 78 release sites located also be provided because they are used psyllid counts dropped from more than in 42 counties throughout the state for host feeding . Finally , the parasitic 100 in 1999 ( before the wasp release ) ( 1,156 Â± 154 per county , range 50 to wasps can be released to the field to fewer than 20 females per trap per 4,016 ) ( table 1 ) . shortly after emergence and mating , as week in 2003 ( after the second wasp Parasitoids were recovered in sticky high rates of egg deposition begin im - release ) . During the same period , trap traps as early as 8 weeks after initial mediately . catches of P . bliteus increased for 3 years release . Recovery in traps occurred ear - after the initial release in June 2000 and Parasitoid release and impact liest in the Central Coast sites , followed then showed steady seasonal cycles . A by the Southern California , North For field release , most parasitoids similar pattern of psyllid decrease and Coast and Central Valley sites ( table were reared at the CDFA Biological parasitoid increase was found farther 2 ) . Psyllid densities typically peaked Control Facility ( Sacramento ) , with north , in San Mateo County ( parasitoids between August and October , and these smaller numbers reared at the UC were originally released in nearby coun - peak periods were used to compare an - Berkeley Insectary and Quarantine ties ) ( fig . 3B ) . In contrast , P . bliteus has nual changes at each site . Eastern Los Facility . Release of P . bliteus began in to date had less effect on psyllid densi - 232 CALIFORNIA AGRICULTURE â?¢ VOLUME 59 , NUMBER 4 TABLE 2 . Average number of days ( Â± standard error ) between initial P . bliteus release and recovery in traps in four Valley sites lag behind the coastal sites cages were far higher at the Berkeley site California regions ( see fig . 4 ) in two measures of parasitoid impact : ( 34.1 % Â± 9.31 % ) than at the Sacramento the time to establishment of parasitoid site ( 1.0 % Â± 1.0 % ) ( 2 - tailed t - test , df = 14 , Region Sites Days Â± SE = 0.003 ) . populations and the overall impact of t = 2.145 , P Central Valley 2 623 Â± 28.0 In a third temperature study , we the parasitoids on psyllid populations . North Coast 5 302 Â± 59.7 compared the longevity of adult fe - Central Coast 5 156 Â± 56.6 To account for these discrepancies , Southern California 13 252 Â± 32.9 male parasitoids held in glass vials at we compared the performance of the the sites in Berkeley and Sacramento parasitoids at coastal and interior sites during summer 2004 . During a period that were paired by latitude using three ties in some interior sites . For example , in June when temperatures were cool measures : ( 1 ) parasitism rates , ( 2 ) the 3 years after parasitoid releases at one in Berkeley but warm in Sacramento , ability of a single wasp to parasitize Sacramento County location , parasitoid the wasps lived significantly longer in psyllids and ( 3 ) the longevity of adult levels were relatively low and psyllid Berkeley ( 14.9 Â± 2.4 days versus 5.8 Â± 0.7 female wasps outdoors . numbers remained high ( fig . 3C ) . days ) ( 2 - tailed t - test , df = 3 , unpaired In the first study , three pairs of To summarize the changes in psyl - t = 3.182 , P = 0.037 ) . During the July and coastal and interior monitoring sites lid density across all 32 monitored September test periods , temperatures were sampled in July 2003 : ( 1 ) Sonoma sites , we compared the average peak were similar at the two sites ( with un - and Sacramento counties , ( 2 ) Alameda densities of psyllids per trap in 2003 to usually cool weather in Sacramento in and Fresno counties and ( 3 ) San Luis those in years before the parasitoid was that part of July ) and the wasps â?? longev - Obispo and Bakersfield counties . Two established ( 1999 to 2001 ) . The results ity was similar at both sites ( averaging 11.8 - inch ( 30 - centimeter ) branch tips of this comparison , grouped by region , 12 to 15 days ) . were taken from each site and up to indicate a postrelease drop in peak psyl - The wasps performed poorly in the 50 nymphs from each sample were lid densities of 78.6 % , 59.5 % and 44.8 % Central Valley compared to coastal ar - dissected to check for parasitism . We in the southern , central and northern eas . Parasitism rates were lower overall found that the average parasitism rate coastal regions , respectively . There was in the field , and individual wasps laid at coastal sites ( Sonoma , Alameda and no change in peak psyllid densities in fewer eggs . A possible explanation for San Luis Obispo counties ) ( 29.7 % Â± 6.6 % ) the Central Valley sites . The postrelease these differences is the shorter lifespan was significantly higher than the average rate of increased parasitoid activity was of the wasps in the summer heat . In parasitism rate ( 1.2 Â± 0.9 % ) at the interior estimated by calculating the average our experiments on the basic biology sites ( Sacramento , Fresno and Kern coun - time from the release to a 50 % or more of the parasitoids , we found that they ties ) ( t - test , P < 0.05 , n = 8 ) . decrease in peak psyllid density on the laid eggs for several weeks in the green - In a second study , three to four mesh monitoring traps . At most coastal sites house , which has mild , cool conditions sleeve cages were fixed to river red ( 18 out of 23 ) the average time to a 50 % similar to the ambient conditions in gums at two paired sites ( Alameda and decrease in psyllid density was 13.2 Â± Berkeley in the summer . However , in Sacramento counties ) in July 2003 . These 1.2 months after the initial parasitoid re - warmer conditions , the wasps did not sites represented the coastal and interior lease . By comparison , at the nine Central live as long and therefore laid fewer temperature regimes at the same lati - Valley sites monitored , there was little eggs over their lifetimes . The relatively tude ; mean average and high tempera - or no detectable effect of P . bliteus on the poor performance of the wasps in the tures for the cities of Berkeley ( Alameda psyllid population densities during the summer in the Central Valley , when County ) and Sacramento ( Sacramento 2001 to 2003 sampling period . psyllid numbers build up to their sea - County ) , where the study was con - sonal peaks , helps explain why we have ducted , are 63 Â° F and 71 Â° F , and 74 Â° F and Coastal versus interior sites observed longer times for wasp estab - 91 Â° F , respectively . Approximately 100 The differences in parasitoid ef - lishment in the interior and , to date , less psyllid eggs were placed in each cage , fectiveness between coastal and inte - impact on psyllid populations . and the resulting nymphs then settled rior sites were most likely due to the on leaves and began feeding . When the Parasitoid impact great climatic differences between the psyllids had reached the third instar , a two regions . The coastal region has By 2003 , P . bliteus had been recov - single female wasp was released into relatively mild summer and winter ered at 29 of the 32 sites monitored each cage . The cages were removed from temperatures , while the interior val - throughout the season with sticky traps . the field 2 weeks later and all psyllids leys have much cooler winters and Field - produced parasitoids far outnum - inside were dissected to check for para - warmer summers . To date , the Central bered insectary production and , for this sitism . Average parasitism rates in the reason , managed releases were discon - tinued . To provide a geographically The red gum lerp psyllid now appears to be under comprehensive summary of parasitoid control in most coastal regions of California due to establishment , we surveyed 55 former release sites throughout California the introduction of a parasitic wasp . from mid - August through October http : / / CaliforniaAgriculture.ucop.edu â?¢ OctOber â?? December 2005 233 in almost all regions and that parasitoid is Farm Advisor , UCCE Monterey County ; activity appears to be increasing annu - C.A . Ingels is Farm Advisor , UCCE Sac - ally . ramento County ; L.G . Varela is Areawide Farm Advisor , North Coast Region ; M.L . Future biocontrol programs Bianchi is Farm Advisor , UCCE San Luis The red gum lerp psyllid now ap - Obispo County ; and G . Taylor is Entomolo - pears to be under control in most coastal gist , University of Adelaide , Waite Campus , regions of California due to the intro - Australia . duction of P . bliteus . Suppression is best We thank the UC Exotic Pests and at coastal sites and lower in some parts Diseases Research Program , UC Statewide of the Central Valley . Our field and labo - Integrated Pest Management Program , ratory studies suggest that the hot sum - Action Mulch , Disney Corp . , East Bay mer temperatures found in the interior Regional Park District , Los Angeles Zoo , regions may reduce parasitoid impact . Rancho Santa Fe Association , Stanford Still , as psyllid numbers have dropped , University Buildings and Grounds Fig . 4 . Percentage of large lerps with parasit - the defoliation and death of eucalyp - Department , and agencies in the cities of oid emergence exit holes during fall survey , tus trees due to the psyllid have been Huntington Beach , Los Angeles , Torrance 2003 ( Roltsch et al . 2004 ) . California county reduced . Of key importance for future and Redwood City for funding . We thank borders demark the four regional sampling control efforts is the observation that Mike Keller , Kerrie Davies and John zones ( except for the Central Valley ) . P . bliteus appears to be well established Jennings of the University of Adelaide , throughout California , including the in - Waite Campus , and Christine Stone of the terior locations . Therefore , although cur - State Forests of New South Wales facility rent P . bliteus densities and parasitism in the Cumberland State Forest for help rates are low in the interior , their impact with foreign exploration . We thank Larry 2003 ( Roltsch et al . 2004 ) . At each site , may continue to increase there , albeit Costello , David Haviland , Daniel Sullivan , 15 branch terminals ( 11.8 to 15.7 inches more slowly than in coastal regions . We Rod Sime and Marta Yamamoto for labora - long ) were randomly collected from will continue to monitor the red gum tory or field assistance . three or more trees . On each branch , lerp psyllid and the parasitoid popula - 30 leaves were randomly selected and References tions to determine if it will be necessary the numbers of exit holes ( round holes Cockerham ST . 2004 . Irrigation and plant - to import either heat - adapted P . bliteus that the adult parasitoid chews in the ing density affect river red gum growth . Cal populations or additional Psyllaephagus lerp when it exits ) , as well as healthy Ag 58 ( 1 ) : 40 â?? 3 . species to improve biological control in Daane KM , Sime KR , Dahlsten DL , et al . and visibly parasitized psyllids , were 2005 . The biology of Psyllaephagus bliteus Californiaâ??s interior . recorded by life stage . Riek ( Hymenoptera : Encyrtidae ) , a parasitoid Parasitoids were recovered at all of the red gum lerp psyllid ( Hemiptera : Psyl - loidea ) . Biol Contr 32 : 228 â?? 35 . but two of 55 locations ( fig . 4 ) . At Dahlsten DL , Copper WA , Daane KM , several locations , levels of parasitoid et al . 1995 . Parasitoid shows potential for activity , as indicated by the propor - D.L . Dahlsten was Professor ( now de - biological control of eugenia psyllid . Cal Ag tion of large lerps containing exit ceased ) , K.M . Daane is Associate UC 49 ( 4 ) : 36 â?? 40 . Dahlsten DL , Rowney DL , Copper WA , et holes , were strikingly higher than Cooperative Extension ( UCCE ) Special - al . 1998 . Parasitoid wasp controls blue gum those found in 2002 , several months ist , K.R . Sime is Postdoctorate Researcher , psyllid . Cal Ag 52 ( 1 ) : 31 â?? 4 . after the initial parasitoid releases , A.B . Lawson was Postdoctorate Researcher Erbilgin N , Dahlsten DL , Chen P . 2004 . Intraguild interactions between generalist using similar survey techniques . For ( currently Assistant Professor , California predators and an introduced parasitoid of example , while P . bliteus was extremely State University , Fresno ) , D.L . Rowney is Glycaspis brimblecombei ( Homoptera : Psyl - rare at the Solano County site in 2002 Statistician , and J.W . Andrews Jr . is Staff loidea ) . Biol Contr 31 : 329 â?? 37 . ( after two releases prior to this sam - Research Associate , Division of Insect Biol - Paine TD , Dahlsten DL , Millar JG , et al . 2000 . UC scientists apply IPM techniques to pling ) , in October 2003 the parasitoid ogy , UC Berkeley ; T.D . Paine is Professor , new eucalyptus pests . Cal Ag 54 ( 6 ) : 8 â?? 13 . was common there . On average over all Department of Entomology , UC Riverside ; Paine TD , Millar JG . 2002 . Insect pests sites sampled , there were parasitoid exit W.J . Roltsch is Associate Environmental of eucalyptus in California : Implications holes in more than one - fifth ( 22 % ) of Research Scientist , California Department of managing invasive species . Bull Ent Res 92 : 147 â?? 51 . the large lerps . We note that while exit of Food and Agriculture ; J.N . Kabashima is Roltsch WJ , Villegas B , Dahlsten DL , et al . holes in the lerps provide an indication County Director and Farm Advisor , UCCE 2004 . Field establishment of Psyllaephagus of parasitoid activity , this may not be Orange County ; D.A . Shaw is Farm Advi - bliteus for control of red gum lerp psyllid on eucalyptus . In : Woods DM ( ed . ) . Biological as accurate as dissecting live psyllids to sor , UCCE San Diego County ; K.L . Robb Control Program Annual Summary , 2003 . Cal - determine the percentage that are para - is County Director and Farm Advisor , ifornia Department of Food and Agriculture , sitized . Still , the survey confirms that Mariposa County ; P.M . Geisel is Farm Ad - Plant Health and Pest Prevention Services , the released P . bliteus have established visor , UCCE Fresno County ; W.E . Chaney Sacramento , CA . p 17 â?? 8 . 234 CALIFORNIA AGRICULTURE â?¢ VOLUME 59 , NUMBER 4