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1 UC Agriulture & Nturl Resoures Cliforni Agriulture Title High temperture ffets olive fruit fly popultions in Cliforni s Centrl Vlley Permlink Journl Cliforni Agriulture, 65(1) ISSN Authors Johnson, Mrshll W Wng, Xin-geng Ndel, Hnnh et l. Pulition Dte Peer reviewed esholrship.org Powered y the Cliforni Digitl Lirry University of Cliforni

2 REVIEW ARTICLE High temperture ffets olive fruit fly popultions in Cliforni s Centrl Vlley y Mrshll W. Johnson, Xin-Geng Wng, Hnnh Ndel, Susn B. Opp, Kris Lynn- Ptterson, Judy Stewrt-Leslie nd Kent M. Dne Mrshll W. Johnson Olive fruit fly ommonly infests olives in Cliforni s Centrl Vlley. Field studies indite tht trp ounts for olive fruit fly dults in pestiide free sites derese in mid nd lte summer nd then reound from Septemer to Novemer. Prt of this deline is ssoited with het stress tht the flies experiene in mid July nd August. Studies hve shown tht dult flies will die within few dys if they nnot ess dequte mounts of wter nd rohydrtes. Flight ility is drmtilly redued when resoures re unville. Olive fruit fly dults my use lk sle honeydew s rohydrte soure to help them survive hot periods. Het lso ffets the fly s reprodution nd immture stges within olive fruit. Geogrphi informtion system (GIS) mps my e useful for prediting the risk of olive fruit fly infesttion. The disovery in 1998 nd susequent spred of the olive fruit fly throughout the mjor olive-produing res of Cliforni drmtilly ffeted the pest mngement tivities prtied y growers. Prior to its introdution, the mjor rthropod pests trgeted for ontrol in Cliforni olives were olive sle (Prltori olee Colvée) (Hempiter: Dispidide) nd lk sle (Sisseti olee [Olivier]) (Hempiter: Coide) (Dne et l. 25). Olive sle is well mnged with iologil ontrol due to the introdution nd estlishment of the prsitoids Aphytis prmuliornis DeBh nd Rosen, nd Coophgoides utilis Doutt (Dne et l. 25). Blk sle is minly ontrolled in the Centrl Vlley An dult femle olive fruit fly deposits n egg into olive fruit. y pruning infested trees to filitte greter ir movement in the summer, whih results in signifint desition of first-instr rwlers (Dne nd Cltgirone 1989). However, the estlishment of olive fruit fly (Btroer olee [Rossi]) (Dipter: Tephritide) fored mny growers onto weekly tretment regime tht runs from mid-june through hrvest (Septemer to Deemer), using the spinosd produt GF-12 NF Nturlyte Fruit Fly Bit (Dow AgroSienes) (Johnson et l. 26). This mngement protool enles growers to deliver fruit with ner-zero infesttion levels to the tle olive proessors. Olives destined for oil pressing my hve signifint levels of infesttion without n ppreile deline in qulity, s long s the time etween hrvest nd pressing is miniml (Pereir et l. 24; Torres-Vill et l. 23). Adult ehvior nd survivl Olive fruit fly dults my e monitored with flt-pnel stiky trps or As tempertures surpss 84 F, dult flies eome inresingly gitted nd egg lying is hlted, nd ove 95 F they re motionless. MPhil trps (Johnson et l. 26). The numers of dults ptured in the Centrl Vlley deline during the hottest periods of July nd August nd inrese in Septemer s tempertures derese (Rie et l. 23; Yokoym et l. 26) (fig. 1). For most inset speies, deline in trp ounts suggests redution in dult densities in n re. This is not initilly the se with olive fruit fly, whose ehvior hnges s dily tempertures rise. Avidov (1954) reported tht elow 62 F the dults re intive. As tempertures inrese ove the threshold temperture, dult tivity inreses. Norml tivity, flight nd egg lying our etween 73 F nd 84 F. As tempertures surpss 84 F, dult flies eome inresingly gitted nd egg lying is hlted, nd ove 95 F they re motionless. Lortory oservtions (M.W. Johnson, unpulished) lso JANUARY MARCH

3 suggest tht dults seek nd remin ner moisture soures s tempertures pproh nd surpss 95 F. Redued dult fly tivity n result in lower trp ounts in the field while mximum dily tempertures remin round 95 F to 99 F nd the flies hve ess to dequte wter nd rohydrte soures (Wng et l. 29). However, s the frequeny t whih dily mximum tempertures equl or surpss 1 F inreses, greter numers of dults will die due to het stress, espeilly when they nnot ess dequte quntities of wter nd food (Wng et l. 29, ) (fig. 2). Although dult femles my ingest liquid from puntures they mke in olive fruit, this seretion does not provide the needed rohydrtes to help them survive het-indued stress (Johnson nd Ndel, unpulished dt). One might ssume tht quisition of dequte mounts of food nd wter would e esy for olive fruit fly dults, whih re strong flyers. Using ustomdesigned flight mill, Wng et l. (29) reported tht dults of oth sexes held for 7 dys t 75 F (onstnt temperture) nd provided with mple food (honey nd hydrolyzed yest) nd wter, were le to fly uninterrupted for n verge of 2,164.8 ± yrds during men period of 1.54 ±.16 hours (fig. 3). Nonetheless, het stress nd lk of wter nd food n ffet flight ility. Olive fruit fly dults tht were sujet to the sme onditions s desried for 7 dys nd then to wter only or no food nd wter in diurnl temperture regimes (65 F t night; 95 F or 1 F during the dy) for 24 hours efore the flight test did not perform s well s the ontrol group (fig. 3). All stressed groups of tested flies flew signifintly shorter distnes ( 42%) thn the ontrol (F 6,252 = 62.7, P <.1). Additionlly, individul flies tht were denied food nd wter from the time tht they emerged s dults nd were held t either 65 F t night nd 95 F, or 1 F, during the dy for 1 to 2 dys, flew signifintly shorter distnes ( 92%) thn the flies provided no food nd wter for 24 hours fter hving ess to food nd wter for 7 dys (fig. 3). In worst-se senrio, n dult fly tht emerges in mid-august in the Centrl Vlley my ommonly experiene mximum dily tempertures over 1 F for 3 onseutive dys (Lynn- Ptterson 26). Without food or wter immeditely ville, n dult will only e le to fly n verge of 16.4 ± 4.4 yrds to lote these resoures in dry nd unexplored lndspe. Men totl flies/trp/week Sites Treted Untreted Men distne (yrds) 2,5 2, 1,5 1, (A) 75 F, food nd wter (B) 95 F, wter, 24 hours (C) 1 F, wter, 24 hours (D) 95 F, no resoures, 24 hours (E) 1 F, no resoures, 24 hours (F) 95 F, no resoures (G) 1 F, no resoures April My June July Aug Sept Ot Nov Fig. 1. Averge olive fruit fly popultions t nine untreted sites (e.g., urn, lndspe nd ndoned ommeril plntings) nd five treted (with GF-12) ommeril sites in Fresno nd Tulre ounties during the 23 growing seson (Johnson, Ndel nd Stewrt-Leslie, unpulished dt). Fig. 2. Mortlity of olive fruit fly dults sujeted to 1 to 3 dys exposure to 95 F nd 1 F, in the sene of food nd with nd without ess to wter (Wng et l. 29). Different letters ove olumns representing the sme temperture/resoure tretment indite signifint differenes (P <.5; Tukey s HSD test) within the exposure durtion. Adult mortlity (%) F, wter 1 F, wter 95 F, no resoures 1 F, no resoures 1 2 Dys of exposure 3 5 Tretment Fig. 3. Men distnes flown y olive fruit fly dults exposed to vrious tempertures nd resoures. Flies (A-E) were preonditioned for 7 dys t 75 F with mple food nd wter prior to tretment. Tretments were: (A) no tretment (ontrol); (B) preonditioned t 95 F, then 24 hours of wter only; (C) preonditioned t 1 F, then 24 hours of wter only; (D) preonditioned t 95 F, then 24 hours with no resoures; (E) preonditioned t 1 F, then 24 hours with no resoures; (F) no preonditioning, held from 1 to 2 dys t 95 F with no resoures; nd (G) no preonditioning, held from 1 to 2 dys t 1 F with no resoures (Wng et l. 29). Different letters ove olumns indite signifint differenes (P <.5; Tukey s HSD test). d d 3 CALIFORNIA AGRICULTURE VOLUME 65, NUMBER 1

4 A B (W) (W) (H) (H) Experimentl setup shows (A) the typil distriution of five olive fruit fly dults (irled) within n oservtion hmer, with otton wiks nd wter (W) nd honey (H) t ool temperture (8 F) nd 2% reltive humidity, nd (B) the ongregtion of olive fruit fly dults (irled) round wter wik (W) when the temperture is hot (99.5 F) nd 37% reltive humidity. Men distne flown uninterrupted (yrds) 2, 1,5 1, F, wter 1 F, wter 95 F, no resoures 1 F, no resoures A C B 1 2 Dys of exposure 3 Fig. 4. Men distnes flown y olive fruit fly dults sujeted to 1 to 3 dys exposure to 95 F nd 1 F, in the sene of food nd with nd without ess to wter (Wng et l. 29). Different letters ove olumns representing the sme temperture/resoure tretment indite signifint differenes (P <.5; Tukey s HSD test) within the exposure durtion. D Suh fly would hve n 84% hne of dying in the first 24 hours, nd of those tht did survive only out 25% would e le to fly (Wng et l. 29). Additionlly, when olive fruit fly dults were held t 65 F t night nd 95 F or 1 F during the dy over 3-dy period with either wter lone or no food or wter, those flies tht survived one dy ould fly signifintly frther thn those tht survived 3 dys (F 2,47 = 18.7, P <.1) (fig. 4). Egg nd lrvl survivl Reprodutive dormny in olive fruit fly susides s greter numers of mture fruit pper within the orhrd, Fly flight is mesured using (A) ustom-designed flight mill setup with omputer; (B) n individul flight mill unit; (C) em tht rottes during inset flight; nd (D) tethered fly fstened to rotting em. ommonly in lte July nd erly August in Cliforni (Burrk nd Zlom 28; Wng et l. 29). During periods of high mximum dily tempertures (3 onseutive dys t 1 F or ove in July nd August) (Lynn-Ptterson 26), mted dult femles my ly their eggs in developing olives prior to morning tempertures rehing 95 F. No eggs re deposited during the night, even when tempertures re ool enough for norml tivity (Avidov 1954; Wng et l. 29). Eggs re deposited just eneth the fruit epidermis nd my e exposed to high tempertures, depending on where n individul fruit is loted on the tree (Wng et l. 29). Lortory studies showed tht dult femles held under different diurnl temperture regimes (65 F t night nd 75 F, 95 F or 1 F during the dy) lid similr numers of eggs when the temperture ws 65 F nd the experimentl hmer ws illuminted (F 2,55 =.2, JANUARY MARCH

5 P =.852). However, under illumintion nd higher tempertures, femles lid signifintly fewer eggs t 95 F (out four per femle) thn t 75 F (out 12 per femle) (F 1,38 = 8.4, P =.6), nd no eggs were lid t 1 F (Wng et l. 29). Even fter eggs re deposited within olive fruit, they re still suseptile to the high tempertures ommon in Centrl Vlley orhrds. Eggs within fruit held t 65 F (night) nd 75 F (dy) developed into first-instr lrve fter 6 dys (Wng et l. 29). In ontrst, eggs within fruit sujeted to 65 F (night) nd 95 F (dy) hd 49% mortlity rte, nd of the first-instr lrve tht did develop, none eme seond instrs. When sujeted to 65 F (night) nd 1 F (dy), no eggs hthed fter 1 dys exposure nd ll died. The overll finding ws tht egg (F 3,57 = 2472, P <.1) nd first-instr (F 3,57 = 2472, P <.1) mortlity inresed s exposure time inresed (Wng et l. 29). Lter field studies showed tht mximum dily tempertures in olive trees in the Centrl Vlley (Prlier) vried depending on whether mesurements were tken within the nopy interior or the est or west perimeter. Men tempertures reorded on the west side of the tree nopy in August 27 were 18 F (nd over 14 F for 26 dys) ompred to 11 F (nd over 14 F for 13 dys) on the est side, nd 96 F (nd never over 14 F) within the nopy interior (F 2,9 = 52.7, P <.1). All of these tempertures re high enough to impose some level of mortlity on olive fruit fly eggs nd lrve. Field studies Olive fruit fly survivl (%) Dys of exposure Honeydew only Honeydew nd wter Honey only Honey nd wter No food Fig. 5. Survivl of olive fruit fly dults when held t 65 F (night) nd 97.5 F (dy) with ess to vrious omintions of wter, honey nd lk sle honeydew, or no food or wter. 4 5 in the sme lolity in mid- nd lte summer 27 nd 28 showed tht less thn 2% of offspring from eggs lid in olives ompleted development to the dult stge (Wng et l. 29). Sle honeydew nd het stress This informtion suggests tht it is diffiult for olive fruit fly dults to survive the high summer tempertures in the Centrl Vlley. Wter my ommonly e found within or ner most orhrds from vriety of soures, suh s morning dew, reeks, ponds, irrigtion wter (dithes nd nls), sprinklers, drip tpe nd fn jets. However, fly dults lso need rohydrtes to survive het stress. Honeydew (fresh or dry) produed y lk sle is ommon rohydrte soure in olive orhrds. Our lortory tests hve shown tht fly dults provided with honey nd wter, or lk sle honeydew nd wter, survive tempertures of 65 F (night) nd 97.5 F (dy) with miniml mortlity ompred to dults only provided honey lone, honeydew lone, or no food nd wter over 5 dys (F 4, 36 = 189.9, P <.1) (fig. 5) (M.W. Johnson nd H. Ndel, unpulished dt). The rohydrte soure lone did not redue the impt of het on survivl. Flies tht hd food resoures (honeydew or pure honey) ut no wter suffered mortlity similr to those flies without food or wter. There ws signifint intertion etween rohydrte soure nd dys of exposure (F 2, 18 = 33.3, P <.1). These results re similr to wht we hve oserved in our lortory nd field studies on olive fruit fly when 5% honey wter ws used s rohydrte soure. These findings re signifint euse they suggest tht olive fruit fly dults ould use lk sle honeydew to help them survive periods of high temperture in the Centrl Vlley. The mngement of lk sle popultions vi ulturl ontrols suh s the pruning of interior nopies my lso ontriute to the mngement of olive fruit fly dults. Temperture mps nd fly tivity Geogrphi informtion systems (GIS) enle the exmintion of temperture trends over speifi res sed on defined riteri, suh s temperture levels for speifi time intervls. The exmintion of temperture trends in olive-produing res in the Centrl Vlley over 1 yers ( ) reveled tht it ws quite ommon for tempertures to e greter thn 1 F for 3 onseutive dys during mid-july nd August (fig. 6) (Lynn-Ptterson 26). On the Cliforni ost, these trends were rrely oserved. Over this time period, tempertures greter thn 1 F for 3 onseutive dys were more ommon in the southern (Sn Joquin Vlley) thn the northern (Srmento Vlley) Centrl Vlley (see By Septemer, most of the Centrl Vlley rrely hd 3 onseutive dys greter thn 1 F (fig. 6).; in 23, olive fruit fly surpssed one dult per trp per week t the end of August nd ontinued to inrese into Novemer (fig. 1). Growers nd onsultnts my wish to use these mps to determine if they n temporrily hlt insetiide tretments for olive fruit fly dults during July nd August. However, there re mny ftors other thn temperture tht influene whether olive fruit fly will e prolem in prtiulr olive orhrd. Olive fruit fly dults with ess to dequte soures of wter nd rohydrtes n survive het stress in lrge numers nd will e le to fly long distnes (more thn 1, yrds) even when stressed. Growers who onsider hlting their ontrol progrms, espeilly in the Sn Joquin Vlley, should tke under onsidertion the irrigtion shedules nd infesttion levels of lk sle nd other insets tht might produe honeydew within their own nd neighoring orhrds. Also importnt is the proximity of irrigtion nls, reeks, ponds nd rivers, s well s ndoned orhrds or untreted olives trees used for lndsping, whih n serve s n infesttion soure of olive fruit fly. Morning dew in the orhrd my provide moisture soure for flies, nd weedy undergrowth in the orhrd or neighoring rops n fford some relief from the het. Perhps the most useful informtion tht one n otin from the GIS mps is knowing when tempertures historilly hve dropped to low levels tht would e onduive to olive fruit fly tivity nd survivl in prtiulr re. As tempertures deline t the end 32 CALIFORNIA AGRICULTURE VOLUME 65, NUMBER 1

6 July 15 Aug. 15 Sept. 15 Ourrenes Fig. 6. Men temperture ptterns in Cliforni over 1 yers ( ), showing numer of yers (ourrenes) with mximum tempertures greter thn or equl to 1 F for 3 onseutive dys ending on July 15, Aug. 15 nd Sept. 15 (Lynn-Ptterson 26). of August, olive fruit re inresing in size nd mturing (Mrtin nd Siett 25). Olive fruit fly dults prefer to ly their eggs in the lrgest olives ville (Neuenshwnder et l. 1985). As flies return to norml tivity in lte summer, the olives remining on the trees re t greter risk of infesttion thn t nytime during the summer, nd proteting the fruit then is of prime onsidertion. Future diretions Reserh on the eology nd mngement of olive fruit fly is ontinuing. A etter understnding of the ilities of olive fruit fly dults to disperse mong orhrds in the summer would e helpful. Given tht olive fruit fly dults need rohydrte soures to survive het stress, it my e est to ontinue treting with GF-12 in July nd August. The dults re ttrted to the sweet fruit fly it in the GF-12. If stressed flies seek rohydrte soure in summer, it my e ssumed tht they would then seek out ville it residues in GF-12. If this is true, the GF-12 my e hving greter impt thn relized. This needs to e determined. Also of importne is the impt of summer het either diretly or indiretly on prsitoid nturl enemies tht re now eing relesed s prt of lssil iologil ontrol progrm for olive fruit fly ontrol (see pge 21). M.W. Johnson is Coopertive Extension Speilist nd Entomologist, Deprtment of Entomology, UC Riverside; X.-G. Wng is Assoite Speilist, Deprtment of Environmentl Siene, Poliy nd Mngement, UC Berkeley; H. Ndel is Supervisory Entomologist, U.S. Deprtment of Agriulture Animl nd Plnt Helth Inspetion Servie, Plnt Protetion nd Qurntine progrm, Buzzrds By, MA; S.B. Opp is Assoite Vie President, Ademi Progrms nd Grdute Studies, Cliforni Stte University, Est By; K. Lynn- Ptterson is GIS Ademi Coordintor, UC Kerney Agriulturl Center, Prlier; J. Stewrt-Leslie is Mnger, Consolidted Centrl Vlley Tle Grpe Pest nd Disese Control Distrit, Exeter, CA; nd K.M. Dne is Coopertive Extension Speilist, Deprtment of Environmentl Siene, Poliy nd Mngement, UC Berkeley. Referenes Avidov Z Further investigtions on the eology of the olive fly (Dus olee, Gmel.) in Isrel. Ktvim 4:39 5. Burrk HJ, Zlom FG. 28. Olive fruit fly, Btroer olee (Gmel.), ovipositionl preferene nd lrvl performne in severl ommerilly importnt olive vrieties in Cliforni. J Eon Entomol 11:75 8. Dne KM, Cltgirone LE Biologil ontrol of lk sle in olives. Cl Ag 43(1):9 11. Dne KM, Rie RE, Zlom FG, et l. 25. Arthropod pests of olive. In: Siett GS, Ferguson L. Olive Prodution Mnul (2nd ed.). UC ANR Pu p Johnson MW, Zlom FG, Vn Steenwyk R, et l. 26. Olive fruit fly mngement guidelines for 26. UC Plnt Protet Qurt 16:1 7. Lynn-Ptterson K. 26. Intertive limte mps for olive fly mngement deisions. uk.edu/cimis. Mrtin GC, Siett GS. 25. Botny of the olive. In: Siett GS, Ferguson L. Olive Prodution Mnul (2nd ed.). UC ANR Pu p Neuenshwnder P, Mihelkis S, Hollowy P, Berhtold W Ftors ffeting the suseptiility of fruits of different olive vrieties to ttk y Dus olee (Gmel.) (Dipt., Tephritide). J Appl Entomol 1: Pereir JA, Alves MR, Csl S, Oliveir MBPP. 24. Effet of olive fruit fly infesttion on the qulity of olive oil from ultivrs Cornos, Mdurl nd Verdel Trnsmontn. Itl J Food Si 16: Rie R, Phillips P, Stewrt-Leslie J, Siett S. 23. Olive fruit fly popultions mesured in Centrl nd Southern Cliforni. Cl Ag 57(4): Torres-Vill LM, Rodriguez-Molin MC, Mrtinez JA. 23. Olive fruit fly dmge nd olive storge effets on pste miroflor nd virgin olive oil idity. Grss Aeites 54: Wng X-G, Johnson MW, Dne KM, Ndel H. 29. High summer tempertures ffet the survivl nd reprodution of olive fruit fly (Dipter: Tephritide). Env Entomol 38: Wng X-G, Johnson MW, Dne KM, Opp S. 29. Comined effets of het stress nd food supply on flight performne of olive fruit fly (Dipter: Tephritide). Ann Entomol So Am 12: Yokoym VY, Rendon P, Sivinski J. 26. Psyttli f. onolor (Hymenopter: Bronide) for iologil ontrol of olive fruit fly (Dipter: Tephritide) in Cliforni. Env Entomol 37: JANUARY MARCH