University of Nersk - Linoln Digitlommons@University of Nersk - Linoln Pulitions from USDA-ARS / UNL Fulty U.S. Deprtment of Agriulture: Agriulturl Reserh Servie, Linoln, Nersk 212 Effets of pyriproxyfen n uprofezin on immture evelopment n reproution in the stle fly Steven S. Xu USDA-ARS, Steven.Xu@rs.us.gov Anrew Y. Li USDA, ARS, Anrew.Li@rs.us.gov Kimerly Huthinson Lohmeyer USDA, ARS, kim.lohmeyer@rs.us.gov Alerto A. Perez De Leon USDA, ARS, eto.perezeleon@rs.us.gov Follow this n itionl works t: http://igitlommons.unl.eu/usrsfpu Xu, Steven S.; Li, Anrew Y.; Lohmeyer, Kimerly Huthinson; n Perez De Leon, Alerto A., "Effets of pyriproxyfen n uprofezin on immture evelopment n reproution in the stle fly" (212). Pulitions from USDA-ARS / UNL Fulty. 111. http://igitlommons.unl.eu/usrsfpu/111 This Artile is rought to you for free n open ess y the U.S. Deprtment of Agriulture: Agriulturl Reserh Servie, Linoln, Nersk t Digitlommons@University of Nersk - Linoln. It hs een epte for inlusion in Pulitions from USDA-ARS / UNL Fulty y n uthorize ministrtor of Digitlommons@University of Nersk - Linoln.
Meil n Veterinry Entomology (212) 26, 379 385 oi: 1.1111/j.1365-2915.212.113.x Effets of pyriproxyfen n uprofezin on immture evelopment n reproution in the stle fly S.S. LIU, A.Y. LI, K.H. LOHMEYER n A.A. PÉREZ DE LEÓN USDA, ARS, Knipling-Bushln U.S. Livestok Insets Reserh Lortory, Kerrville, TX, U.S.A. Astrt. The stle fly, Stomoxys litrns (L.) (Dipter: Musie), is one of the most signifint iting flies tht ffet ttle. The use of tritionl insetiies for stle fly ontrol hs only limite suess owing to the inset s unique feeing ehviours n immture evelopment sites. A lortory stuy ws onute to evlute the effets of two inset growth regultor (IGR) prouts, pyriproxyfen n uprofezin, on the evelopment of the immture stges of the stle fly n the effets of pyriproxyfen on oviposition n egg hth. Both pyriproxyfen n uprofezin h signifint inhiitory effets on immture evelopment. The L 5 s of pyriproxyfen n uprofezin were.2 n 18.92 p.p.m., respetively. Topil tretment of ult femles with ifferent oses of pyriproxyfen h signifint negtive effets on oth femle oviposition n egg hthing when 1- n 3-y-ol femles were trete, n the effets were ose epenent. A signifint reution in the men numer of eggs li ws oserve only t the highest pyriproxyfen ose (8 μg/fly) n egg hth ws unffete y pyriproxyfen tretment when 5-y-ol femles were trete. Results from the present stuy inite tht pyriproxyfen hs the potentil to e use s prt of n integrte stle fly mngement progrmme. Key wors. Stomoxys litrns, iossy, egg hth, inset growth regultor, lrvl evelopment, oviposition, su-lethl effet. Introution The stle fly, Stomoxys litrns (L.), is one of the most signifint iting fly pests tht ffet ttle, horses n ogs (Zumpt, 1973; Foil & Hogsette, 1994). The stle fly hs tritionlly een mjor pest ffeting ttle in iries n feelots (Stork, 1979; mpell et l., 1987), n it hs more reently eome mjor pest of psture ttle s result of the inrese use of roun hy les on pstures, the wste from whih is n iel hitt for stle fly lrve (Broe et l., 25). Pinful ites inflite y stle flies n result in reue weight gin n milk proution, n in some ses ontriutes to reproutive filure (Berry et l., 1983; mpell et l, 1987). The overll eonomi mge to the U.S. ttle inustry is estimte t over 1 illion U.S. ollrs (Tylor & Berkeile, 26). Mnure n green wste snittion hs een regre s the primry metho for stle fly ontrol t onfine ttle opertions (Thoms et l., 1996), wheres the use of insetiies hs only hieve limite suess euse of the unique feeing ehviours of the ult stle fly. It is iffiult to pply insetiie to the lower prts of the niml, prtiulrly legs, where stle flies prefer to fee. Seonry exposure of stle flies to insetiies tht were use to primrily ontrol the horn fly, Hemtoi irritns irritns (L.), n the house fly, Mus omesti (L.) (Dipter: Musie) on ttle or throughout premise ontriute to the evelopment of insetiie resistne in fiel popultions of the stle fly (ilek & Greene, 1994; Mron et l., 1997; Pitzer et l., 21). Reent vnes in stle fly ontrol inlue trete trgets, similr to those use for tsetse fly ontrol, to whih fstting pyrethrois re pplie (Foil & Younger, 26). Firly orresponene: Dr Anrew Y. Li, USDA, ARS, Knipling-Bushln U.S. Livestok Insets Reserh Lortory, 27 Freeriksurg Ro, Kerrville, TX 7828, U.S.A. Tel.: +1 83 792 341; Fx: +1 83 792 314; E-mil: Anrew.Li@rs.us.gov This rtile reports the results of reserh only. Mention of proprietry prout oes not onstitute n enorsement or reommention y the USDA for its use. The USDA is n equl opportunity provier n employer. Pulishe 212. This rtile is U.S. Government work n is in the puli omin in the USA. 379
38 S. S. Liu et l. rpi umultion of n llele tht ontriutes to stle fly pyrethroi resistne evelopment hs een reporte (Olfson et l., 211), suggesting tht it woul e of interest to evlute lterntive insetiies for use on the trete trgets. Inset growth regultors (IGRs), inluing pyriproxyfen n uprofezin, re regre s low-risk insetiies owing to their low toxiity in mmmls n high seletivity ginst trget pest speies (Pener, 22). Pyriproxyfen hs een shown previously to e effetive ginst severl loo-feeing insets, inluing mosquitoes (Mull et l., 1986; Iwng & Kn, 1988), sn flies (Msri et l., 21), tritomi ugs (Lngley et l., 199), tsetse flies (Hrgrove & Lngley, 1993; Lngley et l., 1993) n horn flies (Bull & Meol, 1993). There hs een only one previously pulishe stuy in the literture tht reporte the intertion of pyriproxyfen with the stle fly (Bull & Meol, 1994), n no pulishe work on the effetiveness of uprofezin ginst the stle fly. The ojetives of the present stuy were to evlute the effets of pyriproxyfen n uprofezin on immture evelopment n ult emergene s well s etermine the effets of pyriproxyfen on stle fly oviposition n egg hth. Mterils n methos Flies Stle flies use in the present stuy were from lortory olony mintine t the USDA, ARS, Knipling-Bushln U.S. Livestok Insets Reserh Lortory in Kerrville, TX, U.S.A. The fly olony ws mintine uner ontrolle onitions t 27.8 ± 1 n 6 ± 1% RH with LD 12; 12 h photoperio regime. Ault flies were hel in sreen ge with soli ottom, n fe with ovine loo in otton ps ily. The ovine loo ontine 6.6 g of soium itrte, 264 mg of knmyin sulfte n 264 units of nysttin per liter. Lrve were rere on Purin Fly Lrv Mei (PhrmServ, Frminghm, MA, U.S.A.) overe with penut hull pellets. Insetiies Pyriproxyfen (2-[1-methyl-2-(4-phenoxyphenoxy) ethoxy] pyriine)) (Nylr 1% w/w) ws otine from MGK hemil o. (Minnepolis, MN, U.S.A.). Buprofezin (2-tertutylimino-5-phenyl-3-propn-2-yl-1,3,5-thiizinn-4-one) (4% E) ws kinly provie y Nihino Ameri In. (Wilmington, DE, U.S.A.). Mnure (lrvl iet) iossy To etermine the effets of pyriproxyfen n uprofezin on stle fly lrvl evelopment, mnure (lrvl iet) iossy tehnique ws use (Miller et l., 23). The formulte pyriproxyfen n uprofezin were use to mke seril ilutions in wter. Eight pyriproxyfen onentrtions (,.1,.5,.1,.5,.1,.5 n 1 p.p.m.) n eight uprofezin onentrtions (, 5, 1, 25, 5, 75, n 2 p.p.m.) were prepre in mnure n eh onentrtion ws replite three times. Next, g of ow mnure ws e to 5-mL plsti rinking up. A volume of 5 ml test solution ws e to the mnure in the up n mixe thoroughly with hnhel sptul to generte the esire onentrtion of the IGR in the mnure. Newly eposite stle fly eggs ( 24 h) were ounte into groups of. A group of eggs ws e to the top of the trete mnure. Eh up ws then overe with piee of tissue, n the tissue ws seure with ruer n. The experimentl ups were ple in flyrering room n hel t 25.6 ± 1 n 55 ± 1% RH with LD 12 ; 12 h photoperio for 1 ys. Pupe from eh up were then wshe, ounte n ple in Petri ish for ult emergene. The numer of ult mles n femles ws ounte fter 5 ys. Biossys to etermine the effets of pyriproxyfen on femle oviposition n egg hth To etermine the effets of pyriproxyfen on femle stle fly oviposition n egg-hthing, 5-y-ol ult femle flies were topilly trete with six ifferent oses of pyriproxyfen (.25,.5, 1, 2, 4 n 8 μg/μl) ilute in etone, wheres flies trete with solvent lone were use s ontrol. Eh experimentl n ontrol group omprise of 1 femle n 1 mle ge-mthe 5-y-ol flies, of whih only the femles in the experimentl groups were trete with pyriproxyfen. Ault flies were knoke own riefly with O 2 efore eing ple on ol tle (4 ) to e seprte y sex. ol immoilize flies were trnsferre to ounter top n eh femle in the group ws trete y pplying.5 μl of pyriproxyfen solution (or etone) to the orsl surfe of the thorx using Hmilton repeting ispenser (Moel no. PB6-1; Hmilton ompny, WyReno, NV, U.S.A.). Eh experimentl ose ws replite three times. Eh experimentl group ws trnsferre to smll ylinril fly ge (1 m in imeter 4 m high) n were fe one y y pling 7 m 5 m piee of loo-soke sorent p (Mxim Hygiene Prouts, New York, NY, U.S.A.) on the top of the ge. De mle n femle flies were ounte n remove from eh ge ily. Eggs were ollete from the experimentl n ontrol groups y pling piee of wter-soke sorent p wrppe in lk loth on eh test fly ge in the morning, ily, strting 6 ys post-emergene. The ps were remove from the ges fter 1 h, n the numer of eggs on eh p ws ounte. The sorent p with eggs from eh ge ws trnsferre into plsti Petri ish with wet filter pper n left in the fly-rering room for 48 h efore eggs were exmine to etermine the egg hthing rte. The effet of femle fly ge on its response to pyriproxyfen ws evlute y repeting the experiment using 3- or 1- y-ol flies seprtely. The experimentl protool on 3-yol flies ws extly the sme s for the 5-y-ol flies. However, 1-y-ol flies were highly sensitive to tretment with O 2, ol n etone (1. μl). As onsequene, Pulishe 212. This rtile is U.S. Government work n is in the puli omin in the USA. Meil n Veterinry Entomology, 26, 379 385
Effets of IGR on stle fly evelopment n reproution 381 high perentge (5 7%) of flies ie uring hnling. The experimentl protool ws therefore moifie to minimize fly eth from hnling n tretment. Flies in smll group ( 3 flies t time) were sujet to O 2 nolveryriefly efore topil tretment, n.5 μl (inste of 1. μl) of test solution ws pplie to eh femle fly. The onentrtion of the test solutions ws oule (.5, 1, 2, 4, 8 n 16 μg/μl) in orer to hieve the sme topil ose of pyriproxyfen per fly tht ws use on the other two ge groups of flies (3- n 5-y-ol femles). Dt nlysis POLO-P (LeOr Softwre, 1987) ws use to onut proit nlysis of the osge response of the immture stge of the stle fly to mnure tretment with the two IGRs, pyriproxyfen n uprofezin. To etermine the effets of pyriproxyfen n uprofezin on stle fly evelopment from egg to ult, the t were juste to orret for mortlity in untrete ontrols (Aott, 1925). Perentge inhiition of evelopment ws lulte s follows: I = (1 Nt/N), where I is the per ent inhiition of evelopment; Nt is the numer of ults tht emerge from the trete group; n N is the numer of ults tht emerge from the untrete ontrol group. The men responses mong ifferent tretment groups were sttistilly ompre using the Generl Liner Moels proeure (SAS Institute, 24). Signifint ifferenes were epte t P =.5. Dt were sujete to squre root trnsformtion in orer to stilize vrines efore SAS nlysis. Results Effets of pyriproxyfen n uprofezin on the evelopment of the immture stges The evelopment of the immture stges ws signifintly ffete y pyriproxyfen tretment of mnure (lrvl iet), n the effets were onentrtion epenent (F = 74.1;.f. = 7, 8; P<.1; Fig. 1A). The puption rte ws signifintly reue t pyriproxyfen onentrtion s low s.5 p.p.m. in mnure (Fig. 1A). The tretment of mnure with pyriproxyfen further signifintly reue the rte of ult emergene from the pupl stge (F = 88.6;.f. = 7, 8; P<.1; Fig. 1). No ults emerge t pyriproxyfen onentrtion of.5 p.p.m. or higher (Fig. 1). ompre with the untrete group, pyriproxyfen t onentrtions of.5 n.1 p.p.m. use 3.% n 5.3% reutions in puption rte. Aitionl 83.9% n 91.9% reutions in emergene of ults from pupe were lso oserve for the sme tretment groups (Fig. 1A, ). Buprofezin lso h signifint effets on the lrvl-to-pupl stge of evelopment (F = 4.3,.f. = 7, 22; P<.1) n pupl-to-ult stge of evelopment (F = 12.5;.f. = 12.5; P<.1; Fig. 1B, D); however, ompre with tht of pyriproxyfen, the effet of uprofezin ws reltively wek. A signifint effet of uprofezin on lrv-to-pup evelopment ws oserve t 25 p.p.m., n the formtion of pupe ws ompletely loke t 2 p.p.m. uprofezin. Similrly, signifint reution in ult emergene from the pupl stge ws lso oserve for uprofezin in the rnge of 75 2 p.p.m. Puption rte (%) Emergene rte (%) 8 6 4 2 8 6 4 2 A.1 e.5.1.5.1 Pyriproxyfen (p.p.m) e.5 e 1 e 5 1 25 5 75 Buprofezin (p.p.m) Fig. 1. Effets of pyriproxyfen n uprofezin on puption rte (lrvl-to-pupl evelopment, A n B) n ult emergene rte (pupl-to-ult evelopment, n D) in the stle fly, s ssesse y tretment of the lrvl iet (mnure). Mens with ifferent letters re signifintly ifferent (LSD test, P <.5). Pulishe 212. This rtile is U.S. Government work n is in the puli omin in the USA. Meil n Veterinry Entomology, 26, 379 385 B D e f f 2
382 S. S. Liu et l. % Inhiition % Inhiition A 8 6 4 2 8 6 4 B.1.5.1.5.1 Pyriproxyfen (p.p.m).5 1 responses of the stle fly to the two IGRs, evlute s per ent inhiition of egg-to-ult evelopment, re summrize in Tle 1. The L 5 n L 9 of pyriproxyfen were.2 n.6 p.p.m., respetively, n the L 5 n L 9 of uprofezin were 18.9 n 187.5 p.p.m., respetively. Effets of pyriproxyfen tretment on femle fly oviposition Femle stle flies were topilly trete with ifferent oses of pyriproxyfen t 1, 3, or 5 ys post-emergene. The men numers of eggs eposite per femle uring the first 5-y perio in oth the ontrol (etone only) n pyriproxyfentrete groups from ll three ge groups evlute re shown in Fig. 3. In omprison to the ontrol group, pyriproxyfen tretment of femle flies h signifint effet on the men numer of eggs eposite per femle for the test perio for ll ge groups teste (F 4.6;.f. = 6,14; P <.86), ut signifint effet of pyriproxyfen on the oviposition rte of 5-y-ol femles ws oserve only t the highest pyriproxyfen ose (8 μg/fly). Effet of pyriproxyfen on egg hth of trete femle flies 2 5 1 25 5 75 Buprofezin (p.p.m) 2 Fig. 2. Totl per ent inhiition of the stle fly from egg to ult evelopment s result of tretment of the lrvl iet (mnure) with ifferent onentrtions of pyriproxyfen (A) n uprofezin (B). Mens with ifferent letters re signifintly ifferent (LSD test, P <.5). Egg hthing rtes for 1-, 3-, n 5-y-ol femles trete with vrying onentrtions of pyriproxyfen re presente in Fig. 4. A reution in the egg hth rte ws oserve in eggs li y 1-y-ol pyriproxyfen-trete femles t ose s low s.25 μg/fly (F = 27.4;.f. = 6,14; P<.1). A similr ose-epenent eline in egg hthing ws oserve for the 3-y-ol femle group (F = 4.1;.f. = 6,11; P =.218). No signifint reution in egg hthing (F = 2.4;.f. = 6,13; P =.929) ws oserve in 5-y-ol pyriproxyfen-trete femles. The overll inhiition of egg-to-ult evelopment of the stle fly s result of treting with mnure using the two IGRs is shown in Fig. 2. Pyriproxyfen t s low s.5 p.p.m. in mnure le to 89.8% reution in ult emergene n % reution ws hieve t the onentrtion of.5 p.p.m. (Fig. 2A). Buprofezin use 31.1 49.8% reution in ult emergene t the onentrtion rnge of 5 5 p.p.m., with totl inhiition hieve only t 2 p.p.m. (Fig. 2B). The results of POLO-P nlysis of onentrtion Disussion The results of the present stuy inite tht pyriproxyfen ws highly effetive ginst the immture stges of the stle fly when lrve evelope in pyriproxyfen-trete mnure, with n L 5 of.2 p.p.m. or 2. p.p.. Bull & Meol (1993, 1994) previously reporte the L 5s for pyriproxyfen ginst the immture stge of the horn fly (9.3 p.p..) n the stle fly (12.8 p.p..) using similr mnure iossy. The pyriproxyfen L 5 (.2 p.p.m. or 2 p.p..) for stle fly otine Tle 1. Results of the proit nlysis of ose responses of the stle fly to IGR tretment of mnure (lrvl iet). IGR n* Slope ± SE χ 2 (.f.) L 5 (95% I) L 9 (95% I) Pyriproxyfen 26 2.98 ±.29 14.65 (19).2 (.2.3).6 (.5.7) Buprofezin 3 1.29 ±.15 238.49 (23) 18.92 (1.59 39.47) 187.48 (96.89 1275.64) *n = totl numer of eggs use for mnure iossys. L 5, lethl onentrtion (p.p.m.) tht use 5% immture mortlity. L 9, lethl onentrtion (p.p.m.) tht use 9% immture mortlity. IGR, inset growth regultor; I, onfiene intervl. Pulishe 212. This rtile is U.S. Government work n is in the puli omin in the USA. Meil n Veterinry Entomology, 26, 379 385
Effets of IGR on stle fly evelopment n reproution 383 Eggs per femle Eggs per femle Eggs per femle 2 A 15 5 2 15 5 2 15 5 B.25.5 1 2 4 8 Pyriproxyfen (µg/fly) Fig. 3. Effet of topilly pplie pyriproxyfen on the oviposition of 1-, 3-, n 5-y-ol femle flies, s presente in (A), (B) n (), respetively. Femles were trete with ifferent oses (μg/fly), n the men numer of eggs li per femle uring the first 5 ys of oviposition is presente. Mens in the sme pnel with ifferent letters re signifintly ifferent (LSD test, P <.5). from the present stuy ws six-fol lower thn previously reporte y Bull & Meol (1994). This oul hve een use y ifferenes in experimentl onitions. Nevertheless, results from the present stuy suggest tht pyriproxyfen n potentilly e use for the ontrol of immture stle flies, possily using fee-through formultion n other formultions n elivery methos. As pyriproxyfen is juvenile hormone nlogue tht inhiits inset egg hthing, molting of lrve n ult emergene (Ishy & Horowitz, 1992), we mesure the effets of pyriproxyfen on oth puption (lrvl-to-pupl evelopment) n ult emergene. Pyriproxyfen ws more effetive in inhiiting ult emergene thn preventing the formtion of pupe. The previous stuies y Bull & Meol (1993, 1994) i not ifferentite the effets on puption n ult emergene of horn flies when pyriproxyfen-trete mnure ws teste for reution of ult emergene. Although puption n ult emergene were lso signifintly reue t the higher onentrtions of uprofezin in the present stuy, onentrtions neee were onsierly greter thn the effetive onentrtions for pyriproxyfen. The Egg hthing rte (%) Egg hthing rte (%) Egg hthing rte (%) A 8 6 4 2 B 8 6 4 2 8 6 4 2 Pyriproxyfen (µg/fly).25.5 1 2 4 8 Fig. 4. Effet of topilly pplie pyriproxyfen on the egg hth rte of 1-, 3- n 5-y-ol femle flies, s presente in (A), (B), n (), respetively. Femles were trete with ifferent oses (μg/fly), n the hthing rte of eggs proue y the trete femle flies uring the first 5 ys of oviposition is presente. Mens in the sme pnel with ifferent letters re signifintly ifferent (LSD test, P <.5). uprofezin L 5 (18.92 p.p.m.) ws 946-fol higher thn tht of pyriproxyfen. As result, muh more uprofezin woul e require to hieve the sme level of immture ontrol of pyriproxyfen when use to tret lrvl reeing sites. Topil tretment of femle flies with pyriproxyfen h signifint negtive effet on oth the men numer of eggs li per femle n the egg hthing rte; however, fly ge plye role in the oserve effets. Pyriproxyfen ws effetive in reuing oth the numer of eggs femles proue n the egg hthing rte when 1-y-ol femle flies were trete t ose s low s.25 μg/fly. Pyriproxyfen i not use signifint reutions in egg numer n hthing rte in 3-y-ol femles t pyriproxyfen oses lower thn 2. μg/fly, n the tretment h no effet on 5-y-ol femles, tht my hve fully evelope eggs, exept signifint reution in the numer of eggs li y femles t ose of 8. μg/fly. The t suggests tht pyriproxyfen my inhiit emryogenesis t the erly stge of emryo evelopment, leing to oth e Pulishe 212. This rtile is U.S. Government work n is in the puli omin in the USA. Meil n Veterinry Entomology, 26, 379 385
384 S. S. Liu et l. reue egg proution n egg mortlity fter oviposition. This oservtion onurs with previous finings tht treting freshly li stle fly eggs with pyriproxyfen solution i not hve ny verse effets on egg hth (Bull & Meol, 1994). Lngley et l. (199) previously reporte tht topil ose of.2 μg of pyriproxyfen use ult femle tsetse flies to proue non-vile offspring for her entire life, quntity tht is 1-fol less thn the lowest ose effetive ginst the stle fly. The ifferene oul e ttriute to vrying sensitivities of the two fly speies to this ompoun, or it my lso result from ifferent formultions use n lotions of pplition. Lngley et l. use rpesee oil e to etone solutions of pyriproxyfen t 1 : 4 v/v rtio, n 1 μl of this solution ws pplie to the ventrl omen of the femle tsetse flies. The oil my filitte pyriproxyfen penetrtion of the inset utile n iret pplition of pyriproxyfen to the ventrl omen of the flies my lso help pyriproxyfen iretly reh the trget orgn (ovries). Results from the present stuy emonstrte the effiy of pyriproxyfen ginst stle fly lrve t low onentrtions (L 9 = 6. p.p..) when lrve were expose to trete mnure. Therefore, pyriproxyfen hs the potentil to e use for treting stle fly lrvl hitts. Results of the topil pplition experiment lso illustrte the etrimentl effets of pyriproxyfen on oviposition n egg hth, initing tht iret pplition to reently emerge femle flies my e useful in reuing feunity. Further stuies re neee to evlute the utility of pyriproxyfen s n IGR for the ontrol of the immture stges n s hemil sterilnt for use on trete trgets in n integrte stle fly ontrol progrmme. Aknowlegements The uthors woul like to thnk Drs Pi Olfson n Yu heng Zhu n two nonymous reviewers for ritil review of the mnusript, Mtthew Wlon for mintining the stle fly olony n helping with lrvl iet iossys, n Dri Burhers n DeEst Hytt for their ssistne in iossys. S.S.L. ws supporte y USDA Postotorl Reserh Assoite Progrm wr to A.Y.L. Referenes Aott, W.S. (1925) A metho of omputing the effetiveness of n insetiie. Journl of Eonomi Entomology, 18, 265 267. Berry, I.L., Stge, D.A. & mpell, J.B. (1983) Popultions n eonomi impts of stle flies on ttle. Trnstions of the Amerin Soiety of Agriulturl Engineers, 26, 873 877. Broe, A.B., Hogsette, J. & Pisley, S. (25) Winter feeing sites of hy in roun les s mjor evelopmentl sites of Stomoxys litrns (Dipter: Musie) in pstures in spring n summer. Journl of Eonomi Entomology, 98, 237 2312. Bull, D.L. & Meol, R.W. (1993) Effet n fte of the inset growth regultor pyriproxyfen fter pplition to the horn fly (Dipter: Musie). Journl of Eonomi Entomology, 86, 1754 176. Bull, D.L. & Meol, R.W. (1994) Intertions of the inset growth regultor pyriproxyfen with immture n ult stges of the stle fly. Southwestern Entomologist, 19, 257 263. mpell, J.B., Berry, I.L., Boxler, D.J., Dvis, R.L., lnton, D.. & Deutsher, G.H. (1987) Effets of stle flies (Dipter: Musie) on weight gin n fee effiieny of feelot ttle. 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