Journal of the American Mosquito Control Association,9(3):302-307, 1993 Copyright @ 1993 by the American Mosquito Control Association, Inc. EFFICACY OF TWO FORMULATIONS OF THE INSECT GROWTH REGULATOR, PYRIPROXYFEN G\ryLAR@ OR SUMILARV@), AGAINST NUISANCE CHIRONOMIDAE (DIPTERA) IN MAN.MADE PONDS
ARSHAD ALI, RUI-DE XUE AND RICHARD LOBINSKE
University of Florida, IFAS, Central Florida Research and Education Center 2700 East Celery Avenue,Sanford, FL 32771-9608
ABSTRACT. A juvenoid insect growth regulator, pyriproxyfen (Nylar@ or Sumilarv@), in a l0% emulsifrableconcentrate (10 EC) and a granular (30/osand granules) formulation was evaluatedfor efficacy against natural populations of chironomid midges in man-made ponds in central Florida. Both formu- lations at 0.05 kg Allha induced complete suppressionof adult midge emergencefor I wk. At 0.2 kg AI/ ha, emergenceofadult midgescompletely ceasedfor 2 and 5 wk with the EC and the granules,respectively. The EC formulation was not effective beyond 2 wk, but the granules at both treatment rates reduced midge emergenceby 8l-100o/o for 9 wk posttreatment. The differencesin suppressionof adult midge emergencebetween the 2 formulations and times posttreatment were both highly significant (P < 0.01). No significant difference (P > 0.05) was found between the posttreatment percent inhibition of midge emergenoecaused by the lower and the higher ratesof the granular formulation. Somereductions of midge larvae occurred in the ponds receiving the higher rate of the 2 formulations, but these reductions were statistically not significant.
INTRODUCTION (Marcer et al. 1990), establishesthe importance ofchironomids as urban pestsof seriousconcern. Pyriproxyfen, 2-[ -methyl-2-(4-phenoxy- Reported here is the efrcacy of 2 formulations phenoxy)ethoxylpyridine, is a newly discovered of pyriproxyfen against natural populations of insect growth regulator (IGR) known under the chironomids in man-madeponds. tradenames ofNylar@ and Sumilarvo. This IGR is a juvenile hormone mimic and is highly active againsta wide variety of insectsof public health MATERIALS AND METHODS importance including fleas (Palma and Meola I 990), tsetseflies (Langleyet al. I 990), houseflies The ponds employed are located at the Uni- (Kawada et al. 1987),cockroaches (Koehler and versity of Florida's Central Florida Researchand Pattersonl99l) and mosquitoes(Schaefer et al. Education Center at Sanford. Each artificial pond x 1988, Mulla et al. 1989).Preliminary observa- earthen is 6 4 m and is filled with water tions of Sinegreet al. (1990) and Schaeferand to a depth of 45-50 cm. The water supply to each Miura (1990) indicated that pyriproxyfen was pond is from an underground artesian source, alsoeffective against aquatic chironomid midges. with desired water depth maintained by a float At present,the long-term effectsof the IGR and valve. pyriproxyfen the formulation effects in reducing larval and On July 7, 1992, was applied to ponds granule adult midge populations remain unknown, al- the as a 3olosand and a l0o/oemul- though unpublished results of some field evalu- sifiable concentrate (10 EC) supplied by Mc- ations of pyriproxyfen against chironomids are Laughlin Gormley King Co., Minneapolis, MN. available.t'2The increasingnuisance and eco- Each formulation was applied at 0.05 and 0.2 kg (ponds) nomic problems posed by adult chironomids in Al/ha, with 3 replicates for each rate of ponds recentyears on a global basis (Ali l99la), and treatment. Six were left untreated as con- ponds their worldwide associationwith human allergies trols. Thus, a total of l8 was utilized in this experiment. The ponds were treated in a randomized block design.The required amount of EC for each of the 6 treatment ponds was I Davis, J. A., A. M. Pinder, K. M. Trayler and S. mixed with water in 6 separate0.5-liter squeeze A. Harrington. 1990. Towards moreeffectivecontrol bottles, each containing 300 ml water, and ap- ofnuisance chironomids (midges)in metropolitan wet- plied evenly to the pond surface.The amount of lands, Perth, Western Australia. Unpublished report. granules needed in each treatment pond was Murdoch University, Australia. 2 mixed with 0.5 kg of sterile, clean sand, and the Pinder, A. M., K. M. Trayler and J. A. Davis. pond 1991. Chironomid control in Perth wetlands. Final mixture was dispersedevenly over the sur- report and recommendations. Unpublished report. face. School of Biol. Environ. Sci., Murdoch University, Immediately prior to the treatments, and l, 3 Australia. and 7 days posttreatment and subsequentlyat 302 SsPTErlssn1993 PvnrpnoxvrpN AcuNsr NursANcE CnnoNoutole 303 weekly intervals, one night's emergenceof adult ofChironomini, Tanytarsini and total midgesare chironomids from the treated and control ponds summarized in Table l. Posttreatment data for was assessed.The adult emergencefrom each days 1, 28,42,56, 70 and 84 are not included, pond was sampled with a 30-cm high, metal- but are available. Each rate of both formulations cone, submergedemergence trap (Ali 1980)cov- of pyriproxyfen initially caused complete inhi- ering 0.25 m2 of the pond bottom. Two cones bition of emergenceof Chironomini, Tanytarsini were employed in each pond. Population den- and total midges, but the magnitude and dura- sities of chironomid larvae were also assessedin tion of control varied with the rate of treatment each pond. The larval samples were collected and formulation (Fig. l). The EC formulation at following the adult sampling regime. On each O.05and O.2kg AI/ha causedcomplete inhibi- sampling date, 3 separatemud sampleswere ran- tion of midge emergencefor I and 2 wk post- domly collected from each pond with a 15 x treatment, respectively. The granular formula- 8-cm scoop sampler and composited. The water tion at the samerates was far superior in activity, temperaturewas measureddaily by using a max- causing 50-100, 5l-100 and 5l-100o/oreduc- imum-minimum thermometer placed perma- tions ofadult Chironomini, Tanytarsini and total nently in the middle of one Pond. midges,respectively, for 1l wk posttreatment at In the laboratory, each mud sample was washed 0.05 kg Allha. Overall, the lower rate of the gran- through a 400-pm pore sieve to recover midge ular formulation suppressed 8l-100o/o emer- larvae. The larval and adult samplesfrom each genceof adult midges for more than 2 months. pond were examined for identification and The higher rate of the granular formulation pro- counting. Reductions of midge larvae and adults duced9G-100, 5zf-100 and 8l-1000/oreductions due to the treatments were calculatedby the for- of adult Chironomini, Tanytarsini, and total mula given in Mulla et al. (1971).This formula midges for 9 wk posttreatment, with complete has provisions for adjusting population reduc- inhibition of total midge emergencelasting for tions causedby the treatments in relation to any at least 5 wk posttreatment. In general,the du- simultaneous natural increasesor decreasesof ration of midge control achievedby the 2 appli- populations. The pre- and posttreatment larval cation ratesof the granular formulation was very and adult midge population data were compared similar but the magnitude of control resulting by analysis of variance. A log(n * l) transfor- from the higher rate of treatment was apparently mation was usedon the adult data prior to anal- greater, as indicated by complete inhibition of ysis, because their frequency distribution was adult emergencefor 5 wk posttreatmentachieved highly skewed to the left, reflecting numerous by the higher rate compared to I wk posttreat- zero counts. ment at the lower rate. The differencesin suppressionof adult midge emergencebetween the 2 pyriproxyfen formu- AND DISCUSSION RESULTS lations and times posttreatmentwere both highly The ponds supported populations of Chiro- significant(P < 0.01).Multiple comparisonsre- nomini and Tanytarsini midges. Among Chiro- vealed that the effectivenessofthe granular for- nomini, Polypedilum p arvun Townes and Apedi - mulation in suppressingadult midge emergence lum elachistu^sTownes were the most prevalent; was higher than the EC formulation, compared speciesof Chironomzs also occurred consistent- with the controls (P < 0.01). However, no sig- ly, but in low numbers. Speciesof Tanytarsini nificant difference(P > 0.05) was found between were presentin all the ponds at population levels the posttreatment percent inhibition of midge much lower than those of Chironomini' Specific emergencecaused by the lower and the higher identifications of Tanytarsini could not be made rates of the granular formulation. due to the lack of taxonomic keys. In a few sam- Table 2 presentsdata on midge larval densities ples, adult Tanypodinae, Ablabesmyia mallochi in the treated and control ponds. The lower rate (Walley), Coelotanypus concinnus (Coq.) and of both formulations caused no reductions of Tanypus neopunctipennlsSublette were recog- midge larvae, but the higher rate of EC appar- nized and composed < loloof the total adults col- ently causedreductions up to 660lo(range O-66Vo) lected on any sampling occasion.Because of the and the granules at 0.2 kg Allha causedreduc- low numbers of some Chironomini speciesin tions up to 690/o(range G-6970)of larval popu- some samples,the adult chironomine data were lations during 6 wk posttreatment. These reduc- combined under the tribe Chironomini to elu- tions. however, were statistically not significant cidate the efficacy of pyriproxyfen and its for- (P > 0.05). mulations. In this midge tribe, a few Tanypo- The resultsofthe presentstudy are in complete dinae that occurred sporadically were included. agreementwith those reported from Australia,t Data on the effectsof both formulations ofthe showing >800/oinhibition of chironomid (pre- IGR at 0.05 and 0.2 kg Allha on adult emergence dominantly Polypedilum nubifer Skuse) adult 304 JounN,c.Lor rnr AupnrcAN Mosqurro Cowrnol Assocrerrorq Vor,. 9, No. 3
-E ll ie tl trioo - Oc.l ta F-N O o\€ \o - a..l c.l ciln O\ €C{ O\ OO: O\ cO$ O\d - EF II O- a.l .l!a a- O€ O\ $\O O\ SO .n d# ll $ t.-\O O (.) oo o\ sEiill^ o Ytl +t +t +t lt lr ll SE.lII +r+t +t +t +t +l +t +t +l o I 'Xll \o \o rn r H-ll r|\o FAEII ,-, F .! ll wtr tl h(a oo rr.,l _ ll O\ O\ o! ll +l -Ll -Lt fl lt ll +l ll Jl lr 1r al +l +t +l sE ll $\o o 2o ll P(Dll (\l- (-) c! bo tl oO \OS O\ ON * $co c.l F- F- O\i .'- OO OO !aS =o ll C) H rt F6 tl +l +t +t +l +t +t +t +t +t *t *t rr +l +t +t N dl e ll t? \tF- i eiF- O\ €!a cO lai O tO\$ o a-l !a (r) O\: : N an 9) .r: Il a.l a.l bE ll sn () \ar qc'!q("! ii E tl 99 q '95 ll J ;ttr il e vtl .E 'E 'E 'E II t il 6 E 6 E 6 E 6'E \? a o- ll tr.= !q E.r (l d.- Q E.- cB C.i (q .o0 tl 9.E->.;F.E*>-; I.E->.; F.Ei= v.= > ti ,(s " ll .FE::.=EF H€ II EE:-,".--- E =E:: X FHdA 1 vl-t-vt-t-vl't-vFF O t-:F Srrrgunrn PyRrpRoxyFEN ActNsr NursANcE Cttttotntolratoar 305 PV\ EMULSIFTABLECONCENTBATE (10 EC) O.O5KG AI/HA f:l EMULSTFTABLECONCENTHATE (10 EC) 0.2 KG AI/HA m SANDGBANULES (3Yo G) 0.05KG AI/HA I SANDGRANULES (390 G) 0.2 KG AUHA CHIRONOMlNI 100 ao 60 lrJ 40 o = 20 lrJ o tr o ul = TANYTARSINI UI -t I oo of ao 60 lro z 40 o F 20 E I o = F TOTALMIDGES z loo lu o G BO lrl o. 60 40 20 o 3714213549637791 DAYSPOSTTFEATMENT Fig. l. Percent inhibition of emergenceof adult Chironomini, Tanytarsini and total midges due to treatments with 2 formulations of the IGR pyriproxyfen, each applied at 2 rates to man-made ponds at the University of Florida's Central Florida Researchand Education Center, Sanford. emergence for 3 wk and no reductions of midge chitin synthesis in insects, and juvenile hormone larvae by Sumilarv@ application at 0.05 kg AIl analogs have been evaluated against chirono- ha to metropolitan wetlands in Perth. mids under laboratory and field conditions, as In the past 2 decades, numerous IGRs, in- reviewedbyAli(1993).Amongthebenzoylphe- cluding benzoylphenylureas, which interfere with nylureas, diflubenzuron, Bay SIR-8514, UC- 306 JounNlr- op rnp AuunrclN Moseurro Coxrnol Assocreuor Vor-. 9, No. 3 62644 anduc-84572 were the most effective in $ t-- F- co \O various chironomid control studies, yielding F-e{ !^ -9.E 9! >900/o suppression of adult midge emergence for ': c) at posttreatment $ +t +t +t +t +l up to 5 or 6 wk in some situations !tr Oa- tarla $ at rates ranging from 0.025 to 0.25 kg Allha. Sr'. F-O € (g.5 N Among the juvenile hormone analogs, metho- nf, prene is the most studied IGR for chironomid control. A more recent evaluation of methoprene (*El F- r-.- o F- c.l in different formulations against chironomids in iO a--\o O oY rC\ S the ponds utilized in the present study showed kti +r+t +t +t +l the superiority of sustained release methoprene n: oo!. r, formulations, such as a granular and Altosid@ lg(! \o c.] \o c..l 00 -.{ N XR briquets and pellets over Altosid@ Liquid @0)>e Larvicide at comparable rates of treatment (Ali rdCg 199 lb). The briquet formulation at 0.82 kg AI/ :$ iO i ha reduced adult midge emergence by 38-980/o o\€ ooo o\ ll for 7 wk, and the pellet formulation at 0.22 kg 6tr oo e.l +t +r +t +t +l Allha suppressed emergence of midges by 64- oss c.r !+ oo O\ N () O\ oo \O O\ 98o/o for 7 wk. The present study showed that : a.l pyriproxyfen was far superior in activity to meth- ;v o oprene against chironomids as evidenced by 8l- k l00o/o suppression of adult midge emergence for $F-- *oo e.l 9 wk posttreatment by the granules applied at a &F d: O\t .-. >'; a o ,.,, rate as low as 0.05 kg Allha. x H:' a.l I! tt tt tt +l TI The longer control of chironomids achieved ;: o\ o o\\ a\ls F- - $rO i-oO by the granular formulation of pyriproxyfen at I \J- ;,.: e o^ 0.05 kg AI/ha (or I I ppb) as compared to the -L e>s OO 0.) :v6 liquid formulation is largely attributable to the *94 E.t < t6 better ability of granules to reach and remain in vc I 9?sn o n< : tc.t E \oo' or near the larval biomass (benthos) where the : -e{ F c.l 5s active ingredient is gradually released to prolong o $ 6 ZE-i +r+rE +r+ro+r control. More regulated release of the active in- OJ 9 o. "- { o..o iEIJ. J.l Or- ! ooca gredient of this IGR through formulations such .1c .E e{ c.t c c.t N s ",'09 qcg'aa as pellets and briquets may provide even longer i E,5 a residual activity against chironomids. The ad- TI sorption of pyriproxyfen onto organic matter in I! O\O\ oOO ^9o A r) O\ a.l (\.l the mosquito larval environment and gradual F-. availability of the compound through larva- :Str +t +t +t +l TI :\' feeding (Schaefer et al. 1991) is another reason o co- @ta) (-- c9 O\cn lf\O for the prolonged activity displayed by this IGR trF s d- against mosquitoes and midges in the aquatic environments. The half-life of pyriproxyfen on El@ matter in a dairy lagoon was7.47 d when eo \tr, O\oO rf, organic 4a] (a v€ €n 0. I I kg Allha; the compound readily ai- 6l applied at OJ +t +t +t+t +l adsorbed onto organic matter where it persisted which the Oc.) \OO s for more than 2 months, during time ana +r.) o\s l'- : c.l a.l concentration decayed at an exponential rate E6\ property E> (Schaefer et al. l99l). The adsorption kh gA of pyriproxyfen onto organic matter is particu- ,VJ Na \o \o c.l <' c.l FT larly advantageous for chironomid control. This oO- $oO oO .o@co is because high densities of midge larvae are gen- vc FF qO +t +t +t +l +t erally encountered in polluted habitats rich in O !Q O\ \c| c.t e{ O\ ,q,)v organic matter and also because of the benthic 0) oo H oo: O\ ts at\o ci@ $ .E9 nature of most chironomid larvae, remaining in o E9 or under organic matter accumulated at the hab- e{O F' itat bottom. o-t Pyriproxyfen is environmentally and biologi- q c'l I e.l 5E and €\ d i:vE cally compatible in the aquatic mosquito t AI/ha, pyriproxyfen had no detectableresidues uation of larvicidal potency of insect growth regu- (<0.05 ppb) after 2 d in treated water (Schaefer lator, 2-[l-methyl-2-(4-phenoxyphenoxy)eth- Musca domestica. and Miura 1990). The compound had low and oxylpyridine, againstthe housefly, Sanit.Znol.38:317-322. limited stability in soil and did not rapidly dis- Jpn. J. P. G. and R. S. Patterson. 1991. Incorpo- by leaching, Koehler, place from the upper soil strata ration of pyriproxyfen in a German cockroach (Dic- therefore making it unlikely to build up in soil tyoptera: Blatellidae)management progxam. J. Econ. or penetrateto ground water (Schaeferet al. I 99 1). Entomol. 84:917-921. At 0. I I kg Allha, pyriproxyfen had no residues Iangley, P. A., T. Felton, K. ltatrord and H. Oouchi. (<0.005 ppm) after 3 d in the fish Lepomis mac- I 990. Formulation of pyriproxyfen, a juvenile hor- rochirw(Schaeferand Miura 1990),and was also mone mimic, for tsetsecontrol. Med. Vet. Entomol. safe to a variety of aquatic nontarget organisms 4:127-133. (Schaeferet al. 1988,Schaefer and Miura 1990). Marcer, G., B. Saia,C.Zfiretti, C. Giacomin, F. Aciet- D'Andrea. 1990. Aspetti These attributes and the prolonged activity of to, S. Della Sala and F. sanitari dell'infestazione da Chironomidi, pp. 89- pyriproxyfen against chironomids warrant fur- 99. In: F. D'Andrea and G. Marchese (eds.)' Chi- ther investigations of this IGR (especially for- ronomidi, Culicidi, Simulidi-aspetti sanitari ed mulation research)for chironomid control. An ecologici. Regione Veneto, ULSS 16, S. I' P., Ve- IGR such as pyriproxyfen that has minimal or nezia, Italy. no decimating effects on midge larvae, an im- Mulla, M. S., H. A. Darwazeh and E. T. Schreiber. portant component of the aquatic food chain, is 1989. Impact of new insect growth regulators and highly desirable in aquatic midge control pro- their formulations on mosquito larval development grams. in impoundment and floodwater habitats. J. Am. Mosq. Control Assoc.5:15-20. Mulla. M. S., R. L. Norland, D. M. Fanara, H. A. ACKNOWLEDGMENTS Darwazehand D. W. McKean. 1971. Control of chironomid midges in recreational lakes. J. Econ. This is Florida Agricultural Experiment Sta- Entomol. 64:300-307. tions Journal SeriesNo. R-03006. Gratitude is Palma, K. G. and R. W. Meola. 1990. Field evalu- expressed to Mclaughlin Gormley King Co., ation ofNylar@ for control ofcat fleas(Siphonaptera: Minneapolis, MN, for providing pyriproxyfen Pulicidae)in home yards.J. Med. Entomol. 27:1045- formulations. t049. Schaefer,C. H. and T. Miura. 1990. Chemical per- sistenceand efects of S-31183, 2-[l-methyl-2-@- REFERENCESCITED phenoxyphenoxy)ethoxylpyridine,on aquatic organ- Ali, A. 1980. Diel adult eclosionperiodicity of nui- isms in field tests.J. Econ. Entomol. S3:1768-1776. sancechironomid midges of centralFlorida. Envi- Schaefer,C. H., E. F. Dupras, Jr. and F. S. Mulligan ron.Entomol. 9:365-370. III. 1991. Studiesontheenvironmentalpersistence Ali, A. l99la. Perspectiveson managementof pes- ofS-31 183 (pyriproxyfen): adsorption onto organic tiferousChironomidae (Diptera), an emerging global matter and potential for leaching through soil. Eco- problem.J. Am. Mosq.Control Assoc. T:260-281. toxicol. Environ. Saf. 2 | :207-21 4. Ali, A. l99lb. Activity of new formulationsof Schaefer,C. H., T. Miura, E. F. Dupras, Jr., F. S. methopreneagainst midges (Diptera: Chironomi- Mulligan III and W. H. Wilder. 1988. Efficacy, dae)in experimentalponds. J. Am. Mosq.Control nontarget effects, and chemical persistence of Assoc.7:6 I 6-620. S-31183, a promising mosquito (Diptera: Culicidae) Ali, A. 1993. Nuisanceand economicimpact and control agent.J. Econ.Entomol. 8l:1648-1655. possibilitiesof control.In: P. D. Armitage,L. C. v. Sinegre,G., M. Babinot, G. Vigo and J. N. Tourenq. Pinder and P. S. Cranston (eds.).Chironomidae: bi- 1990. Sensibilit6 de trois espEcesde Chironomus ology and ecology of non-biting midges. Chapman (Diptera) i huit insecticides utilis6s en d6mousti- and Hall, London (in press). cation.Ann. Limnol. 26:65-71. Kawada.H.. K. Dohara and G. Shinio. 1987. Eval-