shortlist oftest plants. developed tohelpresearchers chooseasuitable internationally acceptedprocedures has been species inNewZealand, but asetof feasible totesteveryplant plants. Itisnot non-target to to assesstheriskofdamage Researchers rigorously testallproposedagents else? anything won’teat youbesure they How can hostplants. agents andtheir equilibrium forms betweentheabundance of populations reduce accordingly, soanew increasingly lessabun biocontrol issuccessful, plantsbecome them tofindorseverely host plants–thisisbecause itis difficult for to eradicatetheir unable food becausetheyare of Biocontrol agentsrun out areunlikelytoever same).problem isthe risk ofnativespeciesunexpectedly becoming a million, andoneinone-hundredmillion (the has beencalculatedatbetweenoneinten of thishappening change host,andthechance specialisation makes itdifficult to forthem sometimes close This relativesofthatplant. only utiliseallow them thathostplant,and to developed adaptationshave time, and that plants with theirhost These specialistsintroduction. haveco-evolved usually onlyconsiderspecialist feedersfor biocontrol ofweedsresearchers, andthey Safety issues areforemost intheminds of safety recordandhasprovidedmany benefits. In realitybiocontrol ofweedshasanexcellent ecologicaldisasters. leading tofearsoffurther with theintroduction isoftendirectly compared agents forweeds Theintr highly risky. To some peoplebiological control sounds What arethey goingto eatnext? CONTRO THE BIOLOGICAL TE WHAKAPAU TARU TARU TE WHAKAPAU

oduction ofbiocontrol over alongperiodof of rabbitsorferrets, dant andtheagent harm every plant.If harm – HOW SAFEAREBIOCONTROL ISBN 0 – 478 L OFWEEDSBOOK – November 2008 November 2008 09306 AGENTS FORWEEDS? attack plantsunderar can give “falsepositives” whentheagents Oftentests agents. ofcontrol the realhostrange underestimate usually overestimateratherthan unnatural conditions and represent extreme and Some scientists believethatsafety tests choose inreallife. areableto appropriate becausetheagents alternative hosts) areconsidered more or more feeding ontheirhostandone given theoption of choice tests (wheretheyare real life. Foragentsthatactivelydisperse, continually exposedtono-choicesituations in considered appropriate,becausetheyare alternativehostorstarving)are of feedingonan no-choice tests (wheretheyaregiven theoption agents, fungi, such as thatdispersepassively For kindsofteststouse. most appropriate deciding onthe when biology andbehaviour Researchers carefully consider anagent’s representative plantspecies. distributionused toselectthebest maybe biochemistryand plant morphology, many relatedspeciestotest, factorssuch as are established. arepotentially Whenthere species until thelimits ofaspecies’ hostrange followed byincreasingly tobe tested, firstplantspecies the therefore, are and, risk ofnon-targetattack are mostat closely-related weed Plants thatare to thetarget – 3 tificial experimental more distantlyrelated

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( kowhai showed thattheymightdamage immune ( stemminer extremely promising then itisusually reje beneficialplantsagent islikelytodamage other If thetesting suggests thatapotentialcontrol likelihood ofattack. buildmore up comprehensive a picture ofthe carriedoutinorderto outdoors tests may be conditions. Forthisreasonbothindoorsand never colonises field under beanplants dwarf beans( lintearius spider mite( with thegorse was the case real life.This attackin known to actually been conditionshave never thatthey that isoccasionally seenwhen plant-feeding transitory, ‘spill-over’ oftheseattackswereonly (Table 1).Most standards), including twocasesinNewZealand inadequate bymodern(which wasgenerally predicted bysafety-testing priortorelease, not thatwere agents attackingnon-targetplants occurred. Thereareonlyeight reportsofinsect vast majority nounpredicted host change has the agents (, andfor mites, andfungi), 500different species worldwide,usingnearly weed biocontrol programmesformorethan133 than 1000 To datetherehavebeenmore Have theyevergotitwrong? legumes to otherexotic despite thefactmay thatit cause some damage assimilella olivacea leafbeetle( example thebroom For weed. caused bynotcontrollingthe may be moredamage if beacceptable may target attack See ( Sophora microphylla Cytisus proliferus Conflicts ofinterest. ) and broom shoot ( ) andbroomshootmoth ) for broom was abandoned when tests ) forbroomwasabandonedwhentests ), which during), testing laideggson ) wererecentlyclearedforrelease Pirapion immune Pirapion Phaseolus vulgaris ). ). Inothercases some non- cted. Forexample an attack, a phenomenon attack, aphenomenon

such astreelucerne Tetranychus was rejected ), althoughit Gonioctena Gonioctena Agonopterix Pirapion biocontrol releases highlightsneed forcross-bordereffects the of moth ( can change. A classical biocontrol isirreversible andvalues important. Thisexample highlightsthefactthat but notconsidered was anticipated inthe1960s potential impactonnativethistles the USA.The conicus weevil Thereceptacle ( agents. target plantspeciesfrombiologicalcontrol potentially significant effects onnativenon- recentexamplesof There appeartobeonlytwo agents. mistaken forbiocontrol agents, Fungicommonly See similar. somethingthatlooks by biocontrolagents,but damage toplants isnotcaused identity where ofmistaken timetocases There arefrom interpretation oftheresultsobtained. reflect real-life situations, andimprove their more sophisticatedteststhataccurately and newstudies torefinebestpractice, develop past experience fromboth knowledge gained researchers arecontinually reviewing the caused.any damage Biocontrolofweeds biological faroutweighed control agentshave Overall thebenefitsgainedfrom releasing non-targetdamage. caused unexpected released forbiocontrol pathogensthathavebeen Of the26fungal caused significant economic losses. have not habitat,and species coloniseanew perhaps onornamental an accidentalintroduction, islands, orwas Caribbean release oftheagentinseveral natural dispersalfollowingthedeliberate Florida eitherby motharrivedin testing. The was alsopredicted byhost- Florida, which attacks endangerednativeOpuntiaspp.in provided additional assurance that current best provided additional assurancethatcurrent best species) havebeen surveyed andresults have fungal agents(including threeself-introduced agentsandfive 20invertebrate Sofar damage. non-target for have beenundertakentocheck In NewZealandextensivefollow surveys up Zealand surveysinNew Non-target Insects commonly mistaken forbiocontrol ) attacksnativethistles ( tobeconsidered. Cactoblastis worldwide none have worldwidenonehave Opuntia Cirsium Rhinocyllus . This example example . This

cactorum spp.) in spp.)in ) Table 1: Predicted andobservedno Table 1:Predicted ragwort ( and fireweeds onto attacknative jacobaeae moth ( Cinnabar and hasbeenseen. cases minor non-target damage wasexpected remainingfour ofeightcases.Inthe four out anticipated target attackwas none wasfound in minornon- been expected(Table1).Where have some might when generally absent,even the field. Non-target attackwas will happenin indicator ofwhat practice host-testing isagood Gall Midge,St John’sWort Lesser StJohn’sWortBeetle, Greater StJohn’sWortBeetle, Ragwort Flea Beetle, Old Man’sBeard LeafMiner, Old Man’sBeard LeafFungus, Heather Beetle, Gorse SpiderMite, Cinnabar Moth, Blackberry Rust, Alligator Weed Moth, Scotch ThistleGallFly, Ragwort Seedfly, Nodding ThistleReceptacleWeevil, Nodding ThistleGall Fly, Nodding ThistleCrownWeevil, Mexican DevilGall Fly, Mist FlowerFungus, Fly, Flower Gall Mist Rust, Hieracium Gorse SeedWeevil, Gorse PodMoth, Californian ThistleRust, Broom SeedBeetle, Alligator Weed Moth, Species Predicted Observed S. biserratus S. ) larvae willoccasionally ‘spill-over’ S. jacobaea S.

Cinnabar caterpillaron Lochmaea suturalis whentheyhave defoliated Tyria jacobaeae Puccinia hieracii Phragmidium violaceum succedana Botanophila jacobaeae ). Eight native ). Eight Tetranychus lintearius Bruchidius villosus Exapion ulicis Longitarsus jacobaeae Entyloma ageratinae Procecidochares alani Procecidochares Arcola malloi Agasicles hygrophila Urophora stylata Procecidochares utilis Procecidochares Puccinia punctiformis Urophora solstitialis Urophora Zeuxidiplosis giardi Senecio minimus Chrysolina hyperici Phytomyza vitalbae Chrysolina quadrigemina Potentially minor Yes Phoma clematidina var. Trichosirocalus horridus None Yes None No Potentially minor No Senecio Senecio Potentially minor No Tyria Rhinocyllus conicus piloselloidarum None Yes S. biserratus None No None No Potentially minor Yes n-target attack in New Zealand attack inNewZealand n-target Potentially minor No None No Potentially minor No species None No None No None No

None No None No Potentially major No Potentially major Yes Potentially minor Yes Potentially minor No

Nn No None Potentially major No Nn No None Nn No None Old man’s beardleafminer ( omission ofkeytestplan revolutionised host-plantselection making such testing. Molecularplant speciestouse forhost- and inappropriate plants tobequitedistantly related toragwort shownthese using moleculartechniqueshave adva recent in 1929,but wasreleased were testedbeforecinnabarmoth and ornamental and ornamental native damaging found fungi have shownthat closely-related ornamental old man’s beardfungus ( predictedforthe was Minor non-targetdamage dispersal abilities ofthisagent. such ‘spill-over’ attack, expectfor wouldnormally you further than beard( 4 kmofoldman’s occurred within attackmostly This nontarget C. forsteri native Clematis( will occasionally ‘spill-over’onto aspeciesof ) but thedamage isnotsignificant. Clematis C. foetida owing to theexceptional owing nces inphylogenetics phylogenetics hassince arenotthefungus ts unlikely nowadays.ts unlikely Phoma clematidina C. vitalba ) (and on one occasion ) (andonone Clematis. Phytomyza vitalbaePhytomyza ), whichis Studies ) on )

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that gorse pod moth activityinNewZealandis that gorsepod ( closely-related legumes including Scotchbroom trefoils ( monspessulana Australia andsuggestednative that releasedin was carried outbeforetherust self-introduced toNewZealand. Testing ( Blackberry rust is still presentinNewZealand. and infactthereisnoevidence thatthisfungus deliberately releasedagainstoldman’s beard ( gorse podmoth choice’ situation toarise.The included nowwhenis potentialforsuch a‘no more choice’tests useful. ‘No arealways considered‘choice’ tobe testsat thetimewere was nottestedinpre-releasefeedingtrials, as choice’scenario pods beforebroom.This‘no Zealand, treelucerneproduces plant. InNew thisisnotsignificanttothe although again ( attacking treelucerne native on the once onbushlawyer( been observed ‘spill-over’ only damage has minor some However, attacked. be here might some cultivated thornlessblackberry species Broom seedbeetles( occured. understand thereasonswhythis New Zealandandwenow other plantsin attacked haveunexpectedly Only twoagents now. happen which wouldnever New Zealandplantsbeforehand, any testingof the 1940swithout introducedin This agentwas ison-going. determine theimpactofthisattack ( beetle be true.ThelesserStJohn’swort mayhave sofarconfirmed onecasewherethis occured withtheseagents had becauseofwhat John’s wortagents, wasexpectedwiththeSt non-target attack wherepotentiallymajor Of thethreeinstances Cydia succedana Chrysolina hyperici Fax (09) 574 574 4101 (09) Fax (09)Ph 574 4123 Email: [email protected] NEW ZEALAND 1142 Auckland 92170 Bag Private Landcare Research Paynter Quentin contact: information For further spp). Fieldstudies spp). haverevealed Hypericum japonicum ), treelupin( ) isattackingseveralintroduced Phragmidium violaceum ), French broom ( ), Frenchbroom ) isfeedingandlayingeggs Bruchidius villosus R. cissoides R. Cytisus proliferus Cytisus in the USA, inthe surveys Lupinus arboreus Lupinus ). . Work to . Work Genista Rubus ) are ) are ) has ) seed,

and ) and ) and podmoth Gorse beetle, seed man’s beard fungus, leaf Blackberry rust, Broom often poorlysynchronised See the samespecies. thoroughly tested,evenifitis hadnotbeen released fromapopulationthat ever be would noagents aresult As . UK widerhost-rangethatthe moths haveaslightly Testing hassincerevealedthat thePortuguese New Zealandtoimprove geneticdiversity. Portuguese provenancewerealsoreleased into moths sourced from original specificity testswereperformed on Although gorse flowersandpodswereabsent. attack wasmostprevalentwhen and nontarget reduction intheproblem weed. restoration ofnativehabitatsas aresultof caused bybiocontrolag indirect effect Thelargest reported globally. this hasoccurred, andithasbeenrarely Zealand where inNew noexamples know of we replacement byaworseweed.However, negative outcomeifitledtosoilerosionor Successfully could controlling bea aweed future. allow predictive models tobedeveloped inthe into foodwebsisbeingundertakenmay and before biocontrolagents of ecosystemfunction, levelofknowledge to assessgiven the current intricate andoftensubtle effectsareimpossible thatsuch negative. Currentlymanybelieve ‘downstream’ effectsandmaybepositiveor These arealsoreferredtoas‘ripple’or diseasecompetitor, or vector. a foodsource, ecosystems whenthebi could beindirect non-targeteffectson damages anotherplant)itispossible thatthere As wellasdirect effects(thebiocontrolagent Downstream effects Cinnabar moth, Oldman’sbeardleafminer, Cinnabar moth, England, moths of but theyareconsidered ocontrol agentbecomes ents is likely to be the ents islikelytobethe are released. Research are released. with gorse flowering with gorseflowering

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