Burlando, Tom M. : T. M. Burlando is Staff Research Associate, Department of Nematology, UC Davis, and is now a research scientist with the USDA, Cornell University, Ithaca, New York.

Kaya, Harry K.

Timper, Patricia : P. Timper was Graduate Student, Department of Nematology, UC Davis, and is now a research scientist with the USDA, Cornell University, Ithaca, New York.

Above : Containerizedlandscapeplantingof kangarooivy in a commercial complex is infestedwith black vine weevil . At left:Healthy larva and pupa are seen , left ; steinernematid - infectedblack vine weevil larva and two pupaeare right . In outdoor planters in co ~ ~ ercciean ~ ters . . . Insect - parasitic nematodes are effective against black vine weevil Tom M . Burlando o Harry K . Kaya a Patricialimper favoredhosts for BVW . A partial list of scribedpreviouslyin CaliforniaAgriculture Insect - parasiticnematodes sup - plants susceptibleto BVW includesaza - ( March - April1984 , January - February pressed black vine weevil larvae in leas , cyclamens , escallonias , euonomyous , 1985 , and May - June1989 ) . planters containingivy vines at a grapes , ivy , liquidamber , junipers , and Briefly , the flightless , parthenogenetic commercialbuilding.After 1 year , rhododendrons.Because all BVWs are fe - females ( malesareunknown in this spe - male , infestationcan start with one adult cies ) emergein early springand feed vating weevil numbers were lower in con - and spread throughoutplantings or by the night on foliage , characteristicallylea tainers treated with nematodes ei - moving of infested plants or soil contain - l smallnotches alongleaf margins.From 20 ther with or without an added alter - ing eggs , larvaeor adults.The nocturna to 30 days after emergence , the females nate host . habit of BVW adultsand the location of start depositingeggs at the soilsurface larvae and pupae in soil make detection near plants . Each femalecan produce up difficult.Once established , an infestation to 500 eggs.Hatchingoccurswithin 10 The black vine weevil ( BVW ) , Otiorhyn - may go undetectedfor severalyears and days at soil temperatures of 24 ° C ( 75 ° F ) . chus sulcatus , has long been recognized as may onlybe noticed when plants start to The white , leglesslarvae feed on the roots ; a seriouspest of container - grownnursery show dieback . under high population densitiesthey plants , ornamentalsin landscapesand BVW infestationsin nurseries , outdoor girdle plants at the soil surface , killing field vine crops.Its larvae cause damageat landscapesand field vine crops can be soil them . BVW larvae overwinterin the by feedingon roots and girdlingstems suppressed , oftenwith chemical insecti - until pupation occursin spring . the soil surface.This univoltinespecies cides , but in commercialareascatering to Many of the plants beauhfymgshop - ( havingone generationper year ) and its shoppersand outdoordinersand sur - ping centersand commercial buildings are associatedfeedingdamagehave been de - 16 CALIFORNIA AGRICULTURE , VOLUME 47 , NUMBER 3 Similar trends were observed with H . biosys ( PaloAlto , California ) and roundedby containerized plants , chemical bacteriopkora , although at a lower level of Bioenterprises ( Roseville , Australia ) , re - is difficult.Biological control , control nematodeinfectioncomparedwith S . spectively.Therewere six treatments : ( 1 ) therefore , is an attractivealternative . feltiae ( fig . 2 ) . Therewas no differencein with Galleria , ( 2 ) without Galleria , ( 3 ) with Alerted to an infestationin outdoor con - nematodepersistence amongplantersr S . feltiae and Galleria , ( 4 ) with S . feltiae and tainerizedplants within a commercial with or without the alternatehost fo the without Galleria , ( 5 ) withH . bacteriophora complex in San Franciscoâ??s Embarcadero , first 70 days.After this period , the percent - and Galleria , and ( 6 ) with H . bacteriopkora we initiateda year - longbiologicalcontrol age of H . bacteriopkora - infected bioassayin - and without Galleria.Each treatment was program against BVW larvaeand pupae , sectsdropped drastically , rebounding replicated three times with fourplanters using insect - parasiticnematodes . slightlybetween 80 and 100days , and per replicate.Plants were watered , fertil - Experiment background ized , and maintained by groundsperson - nel at the center . BVW larvaeand pupae arehighly sus - Steinernemafeltiae and H . bacteriopkora ceptibleto insect - parasiticnematodesin were applied at a rate of 50 nematodes / the fainiliesSteinernematidaeand cm2and74 nematodes / anz ( 327and 474 / Heterorhabditidae.These nematodes , pests , inch2 ) r , espectively.Nematodeswere ap - most useful againstmany soilinsect plied with a hand - held , 8 - liter ( 2 - gal ) possessmany attributes of successfulbio - Hudson sprayeron February 3,1989 be - logicalcontrolagents , includingtheir abil - y tween 6and 8 a.m . The alternatehost wasn ity to activelyseek hosts , their availabilit 2o 1 ; â?쳌 wit ; ; Iternat ; host / ( placed into the soilbefore the applicatio from commercial sources , the safetyin - - t without alternatehost and again on May 26,1989 . Before treat - which they can be used amongnontarget 2 0 , ment , each planterâ??s soil was bioassayed to organismsincludinghumansand their 0 100 200 300 400 determinethe presence of naturally occur - easein application.Free - living , infective - Daysafter application ring nematodes.Three soilsubsamples stagenematodes , applied to the soilfor in - Fig . 1 . Mean percentageof nematode - in - were taken ( about17cm3for each sect control , seek and penetrate a suitable fected bioassay insects ( Galleria ) recov - subsamplefromaround the base of each insecthost , causing deathwithin 48 hours . ered in 1 year from soil treated with Steiner - ivy vine within a planter ) , placed into a The nematodescompletetheir life cycle nema feltiae . ( Arrows indicatetimes when 250 - cc ( 9 - 02 ) plasticcup , transported to the within theinsectcadaver . the alternate host was added to planters . ) laboratory , and baited with six Galleria lar - Previously , we had established that vae that servedas thebioassayinsect tositic without an insecthost in the soil , the infec - detect the presence of the insect - para tive - stagenematode did not survivefor Heterorhabditisbacteriophora nematodes.The cupswere capped and more than 50 days . Because we were un - stored at room temperature.One week able to assessthe initial BVW population - + . - with alternatehost later , the bioassayinsectswere removed densitiesin the containers , we incorpo - - - f without alternatehost from the cups , and the dead larvae dis - rated a nonplant feeding ( nonphyto - sectedand examinedfor the presence of phagous ) alternatehost to enhancetheprog - nematodes.Using this samebioassay tech - nematodesâ??ability to produce viable nique at prescribed intervals ( 2 to 3 weeks ) eny and to survive.Our objective was to after treatment , the soilfrom each planter establishtheseinsect - parasiticnematodes was sampled separatelyfor nematodeper - as long - term controlagents of BVW . sistence.Nematodepersistencein the soil Experimentâ??s design Days after application was measured by the percentage of the bioassayinsectsinfectedwith nematodes . Our approachwas to enhancethe re - Fig . 2 . Mean percentageof nematode - in - Allsoilswere steam - sterilizedand re - ng.At production of these insect - parasiticnema - fected bioassay insects ( Galleria ) recov - turned to planters after each sampli todes ( andtheir long - term control ofoivy ered in 1 year from soil treated with the end of the experimenton February 15 , BVW ) in soilplanted with kangaro Heterorhabditisbacteriophora . ( Arrows in - dicate times when the alternatehost was 1990 , all planters were destructively ( Cissusantarctica ) vines.Fiberglassplant - addedto planters . ) sampledby removingthe soil and count - ers , 18x 61 x 23 cm ( 7x 24 x 9 inches ) ing the number of livingBVW larvaeand deep , with three drainage holesin the bot - pupae . tom , contained three ivy vines and a com - owithout Galleria mercialpotting soil of 79 % sand , 17 % silt Iwith Galleria Results and 4 % clay . The soilconsisted of 25.5 % nd No insect - parasiticnematodeswere organicmatter and had a pH of 4.7a an A found in any plantersbeforenematodes electricalconductivityof 5.6 . To determinect nA were added or from controlplanters with whether the presence of an alternateinse or without the addition of the alternate host would bolster nematodepersistence host after treatment.In the S.feltiae plots , and BVW control , half of the treatments there was no differencein nematodeper - received 10mature Galleriarnellonella lar - , I1 bL sistencebetween planterswith or without vae.These nonfeeding , nonphytophagous the alternatehost for the first 100days af - larvae , which arehighly susceptibleto the Control Steinernema Heterorhabditis ter application ( fig . 1 ) . However , after the nematodes , were buried about 2.5 cm ( 1 second addition of the alternatehost ( 112 inch ) deep and spaced equallyaround the Fig . 3 . The mean number of black vine wee - days after nematodeapplication ) , the per - perimeter of eachplanter . vils per planter in control , Steinernema centage of bioassay insectsinfectedwith feltiae , and Heterorhabditisbacteriophora The nematodesused in the experi - in the nematodeswas usually higher treatmentswith and withoutthe addition of ments , Steinernemafeltiae ( = bibionis ) FN an alternatehost . Bars with the same letter planterswith the alternatehost than in strainand Heterorkabditis bacteriopkora NC1 are not significantlydifferent at the 5 % level . those without the alternatehost . strain , were obtainedcommerciallyfrom CALIFORNIA AGRICULTURE , MAY - JUNE 1993 17 then droppingto less than 10 % between 100and 140days.In planters with the sec - ond addition of the alternatehost , there was a marked increasein bioassay insectsys infectedwith the nematodefrom 160da onward.Planterswithoutthe alternate host remained at a low level ( lessthan 15 % bioassayinsectsinfected ) until 240 days when the percentage of infectedbioassay insectsincreasedto 50 % . Both S.feltiaeand H . bacteriophoratreat - er ments with the alternatehost had a high nematodepopulation thantreatments withoutthe alternatehost , suggestingthat the nematodesused them to reproduce . Yet , the long persistence of S.feltiaeand H . bacteriophorain treatmentswithoutthe al - ternatehost suggestedthat they , too , were BVW larvaeand pupae . In - reproducingin deed , upon destructivesampling of all planters at the end of the experiment , BVW larvaeand pupae were recovered fromall treatments ( fig . 3 ) . Controlplant - ershad sigruticantlyhigher BVW popula - tions than did the nematodetreatments , but no sigruficantdifferenceswere ob - Almond orchard being irrigated with sprinklers . servedamongnematode treatmentswith or without the alternatehost . Conclusions Our experimentdemonstrated that S . feltiae and H . bacteriophoracan reproduce Uniformity in pressurized when suitablehosts arepresent in potted soil.More significantly , the nematodesre - duced BVW infestationsto a very low irrigation systems depends level.The periodicaddition of alternate hosts to boost nematodepopulationsis not practicalfor these commercialbuildings on design , installation where largenumbers of planters aremain - c tained for severalyears . Rather , a periodi check for BVW as previouslysuggested Gordon E . Little CI David J . Hills R Blaine R . Hanson ( CaliforniaAgriculture , January - February 1985 ) may be a more prudent method for managing this insect . If BVW arefound , this total , 258 reportspertain to pres - Of Of 258 irrigation systems evaluated nematodescanbe applied and then aug - surized irrigationsystemsfor orchards - by mobile field laboratoriesin five mented , asneeded , to bolster the existing 189micro - spray , 56 drip and 13 sprinkler . Southern Californiaresource con - nematodepopulation in suppressingthis The orchards , deciduous , citrusand avo - servation districts , average unifor - pest . Because they aresafeto use and their cado , are alllocated in Kern , Ventura , Riv - mity in distribution of water was potentialfor long - term controlis evident , ersideand San Diego counties.Farmsvary insect - parasitic - nematodesare preferable in sizefrom a few acresup to 400 and in relatively low . Generally , farms to chemical controlin managing BVW in agebetween 1year and 30 . larger than 700 acres had systems buildingswith containerizedlandscapes . Field teams collected data on hardware with higher uniformityin distribu - size , type and location , and on water pres - ~ tion . Age of a system did not nec - suresand dischargeflowrates at strategic T.M . Burlandois Staff Research Associate , H . essarily account for poor distribu - points in the system.Informationon K . Kaya is Professor , and P . Timperwas chemicalinjection , filtrationand lateral tion . What did account for it was Graduate Student , Department of Nematol - flushingwas also obtained.Teams evalu - variationin pressures due to inad - ogy , UC Davis , and is now a researchscientist ated singleirrigationeventsand the irriga - equate system design or to instal - tion systemâ??s water distributionunifor - with the USDA , Cornell University , Ithaca , lation of incorrect hardware . New York . mity.Using these data and information gainedfrominterviewswith growers , the Theauthors thankMark Buttner , grounds teams also estimatedeach farmâ??sannual supervisorof the San Francisco commercial To encourage conservation of agricultural building complex where the researchwas con - irrigationefficiency . water , the Mobile Field Lab Program , ducted ; A1 Hom of biosys , Palo Alto , Califor - sponsoredby the CaliforniaDepartment Background nia , and Bioentevprises of Australiafor their of Water Resources and local resource con - Primaryemphasiswas on each assistance , aswell as the Elvenia J . Slosson En - servationdistricts ( RCDs ) , has evaluated systemâ??sdistributionuniformity ( DU ) , a dowmentFund for itsfinancial support . 1,200farm irrigationsystems since 1985 . CALIFORNIA AGRICULTURE , VOLUME 47 , NUMBER 3 18