Journal of the American Mosquito Control Association, 15(3):4O0-4O6,1999 Copyright O 1999 by the American Mosquito Control Association, Inc.

DEVELOPMENT OF THE FIRST BLACK (DIPTERA: SIMULIIDAE) MANAGEMENT PROGRAM IN ARGENTINA AND COMPARISON WITH OTHER PROGRAMS

ELMER W. GRAY,' PETER H. ADLER,I CECILIA COSCARON-ARIAS.' SIXTO COSCARON3 EIO RAYMOND NOBLET4

ABSTRACT. In response to increasing pest populations of black , the government of Argentina initiated a pilot program to evaluate the effectiveness of larval control in the irrigation system of the Negro River Valley, an 18,240-km' area in Patagonia. The extensive system of irrigation canals, drainage ditches, and natural wa- terways not only provides water for agriculture and general habitation but also affords habitat for immature black flies. Three species (Simulium bonaerense, Simulium wolffiuegeli, and. Simulium nigristrigatum) are pri- mary pests of humans and in this area. Trials were conducted using Vectobac@ AS in representative irrigation canals, a drainage ditch, and a medium-sized river. Most trials resulted in effective larval mortality and insecticide carry. Based on a comparison with I I black fly suppression programs throughout the world, a suppression program for the Negro River Valley has a projected cost of approximately $1,623,360/year. This study represents the initial steps in development of the lst areawide black fly suppression program in Argentina.

KEY WOR-DS Black flies, management program, Argentina, Bacillus thuringiensis var. israelensis

INTRODUCTION locities and larval habitat of lower quality, with only about 6OVoofthe system producing black flies. In 1991, the government of Argentina initiated a Initial studies identified 3 pestiferous species in program to investigate the ecology and manage- the Negro River Valley: Simulium bonaerense Cos- ment of black fly populations in the Negro River car6n and Wygodzinsky, Simulium wolffiuegeli Valley. This valley includes the Limay (721 m3/sec) (Enderlein), and Simulium nigristrigatum (Ender- and Neuquen (302 m3/sec) rivers that converge to Iein) (Coscar6n-Arias 1997). These species are bit- form the Negro River (1,023 m3lsec). The Negro ing and nuisance pests of residents, workers, and River Valley is in Patagonia, which is characterized livestock. The purpose of our study is to provide as desert, receiving an average of only 20O mm of information on a pilot-management program for rain per year. The valley has about 700,000 inhab- black flies in the Negro River Valley and to com- itants, encompasses approximately 18,240 km2, and pare projected costs with those of similar programs is surrounded by desert plains. In the early 19OOs, in other parts of the world. The establishment of an an extensive canal system was constructed to pro- areawide black fly management program in this vide irrigation for farming. The Negro River Valley valley would constitute the lst black fly suppres- has approximately 87,316 ha of fruit and vegetable sion program in Argentina. production. Substantial numbers of livestock, in- cluding cattle, sheep, horses, and poultry, also are MATERIALS AND METHODS raised in the valley. While providing the water nec- essary for agriculture and general habitation of this Study sites: Five field evaluations, using Bacillus region, the canal system also provides ideal habitat thuringiensis Berliner var. israelensis (B.r.i.), were for larval black flies. conducted February 18-26, 1997 (late surnmer in The system incorporates 2'79 krn of canal in the southern hemisphere): 3 in irrigation canals, I in a middle valley. The area considered the upper valley medium-sized river channel, and 1 in a drainage contains a similar canal structure. Each valley also ditch (Table 1). Irrigation canals in the Negro River has about 150 km of drainage ditches to remove Valley are typically steep-sided, flat-bottomed, and excess irrigation water. The majority (>9OVo) of the straight. Drainage channels have gradually sloped canal system provides suitable black fly habitat. banks and slower velocities and lower discharges However, the drainage system has slower water ve- than canals. Canal VI had a flow of 3.23 m3/sec and was straight, with the exception of 2 45" bends in the I Clemson University, Department of Entomology, evaluation area. Canal VII had a flow of 3.49 rlr3/ Long Hall, Box 340365, Clemson, SC 29634-0365. sec and was evaluated over a straight, 3,0O0-m sec- 2 Facultad de Ciencias Agrarias, Universidad Nacional tion. This canal supports dense beds ofaquatic veg- Del Comahue, CC 85, 8303 Cinco Saltos, Rio Negro, Ar- etation (Potamogeton sp.) and is typical of many of gentina. the irrigation canals in the Negro River Valley. Ca- 3 Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque S/N, 1900 La nal VIII had a flow of 11.5 m3/sec and originated Plata, Argentina. at the same water-control structure as Canal VI. Ca- a University of Georgia, Department of Entomology, nal VII originated 50 m downstream of the water- 413 Biological Sciences Bldg., Athens, GA30602-2603. control structure that created Canal VI[. All of

400 Snprsi\assn1999 Ble,cr Flv MaNecsN4BNr n AncrNrtNe 401

these canals are in the Lamarque farms area in the middle valley of the Rio Negro province. The Rio Salado is a medium-sized river extend- e Nn$nr) o C.I N ing from the town of Chimpay to the town of Choe- le Choel. This area also is located in the middle valley of the Rio Negro province. The Rio Salado had a flow of 5.58 m3/sec on the date measured. Its flow, however, is directly related to the level of the tr- Negro River and is typically higher than measured during this study. The Negro River Valley was ex- ?l o^- o\ t'..F r) o ol cl c'.1N c.) periencing a dry period, and all rivers were lower 6 -. O than normal during our study. Flow in the Rio Sal- o ado was relatively uniform through the first 1,50O lJ. m. Beyond 1,500 m, no suitable larval habitat was present untll 2,2OO m below the treatment site. The d I area between these 2 sites had slow water, with a \oooor) o -€ u^v 100-m stretch of dense aquatic vegetation. o0 e A-- H N ti c'.1 c.l Drainage Plottier (Neuquen province) represent- 0 * ed a typical drainage channel in the valley region. C) It had a flow of 0.31 m3/sec at the treatment site and 0.40 m3/sec at the most distant evaluation site (2,300 o m). The area betweeh 1,200 m and 2,300 m was virtually inaccessible. A 20O- to 300-m stretch afF-nc.ii of slow flow followed r;+oi+r; the l,2OO-m site. c.l Application and evaluation: a TIte lst field trial z (Canal VI) was conducted with a Vectobac@ AS q F (600 ITU-Abbott Laboratories, N. Chicago, IL) .B.r.1.product (lot no. O9-244-SL) that was produced in September 1995 and had a use-by date of Sep- tember 1996. This product had been stored at room ' iOhr+\O 0) v?\q9q temperature since receipt by the Universidad Na- 20. B cional Del Comahue in Cinco Saltos, Argentina. Vectobac AS (lot no. 2O-628-51) rhat was manu- factured in August 1996 was used in all subsequent a trials. Flow measurements were conducted following the recommendations of Horosko :.; 3 ol \o t-.. \o 00 and Noblet :: €ONoC.l (1986), with the following exception. Velocity mea- zutre-i* -; ...i.: ci d 6l surements on February 18 and 20 were conducted with a Fisons Scientific Equipment velocity meter q)l (MJP-Geopacks, Cornwall, Trinidad). We used corks and a stopwatch to calculate velocity on the remaining treatment days. Surface velocities were 4l 0l multiplied by 0.8 to adjusr for flow velocities ! 0) tsl .E throughout the water column (Colbo 1985, Molloy OI 6 and Struble 1989). ol ; HI o Larval mortality was evaluated using techniques >>>S yo similar to those of Gray et al. (1996). B Mortality evaluations were conducted at various distances :!:o!E I downstream from (Table (.)| udd;t6 the treatment site 2), de- pending on individual waterway characteristics, lar- -l val substrates, and the dose. A minimum of 100 I larvae were collected approximately 5 h posttreat- I I ment by removing pieces of substrate and returning I I them to the laboratory in ice chests. Samples were aerated with aquarium pumps. At approximately 24 ooooV)\o I i N Ol a'.1c.l h posttreatment I each sample was poured in a white I >'>>'>>. EE!EH pan I enamel and the percent mortality was deter- I I ELLHT mined. I Adult monitoring was conducted on I ,9 ,9 .9 ,9 ,9 9 occasions from February 18 to 27,1997, following the pro- 402 JounNer-or rnn AuentcAN MoseulTo CoNrnol AssocrnrroN Vor-. 15, No. 3

Table 2. Larval mortality evaluations in 5 waterways in the Negro River Valley, Argentina, February 1997.

Percent mortality (r?) Site m down- Drainage stream Canal VI Canal VII Canal VIII Rio Salado Plottier Control (0) 0.3 (307) o.o(127) 0.3(361) 2.4(295) 0.0(158) 500-1,000 100.0(202) 100.0(150x 99.r (2r3) l,000-1,500 99.6 (264)l q{ I /l {7\4 91.s(236) I,500-2,000 71.6(278) 8O.4(224) 9s.2(210) 2,000-2,500 99.s (222) 62.9(3o7) 60.s(778) s.6(199) 2,500-3,000 89.9(139)' 4O.2(r37) 87.9 (2oo) 3,000-3,500 92.7 (42s) 88.8(295)3 3.9(383) 3,500-4,000 61.5(191) 88.7(363)3 4,000-4,700 74.3 (288) rAdditional mortality evaluations were made at 2 sites in a side channel downstream of a water-control structure located 1,100 m below the treatment site: 1,300 m, mortality :98.2Vo (n: 327);1,880 m, mortality -- 92.4E" (a : 238). 2 Additional monality evaluations were made at 2 sites in a side channel downstream of a 2nd water-control structure that was located 1,880 m below the treatment site on the lst side channel: 2,52O m, mortality :77-5Vo (n - 325)',2,580 m, mortaliry :2.8Vo (n: 248). r Additional mortality evaluations were made at 2 sites in a side channel downstream of a water-control structure that was located 3,400 m below the treatment site: 3,450 m, mortality - 2l.2Vo (n - I l3); 3,700 m, mortality - 41.3o/o(n : 189). a Mortality was evaluated 5 h after application; all other samples were evaluated 24 h after application.

cedure of Gray et al. (1996). An individual stood RESULTS AND DISCUSSION at a site for 5 min before making 10 figure-8 Species composition sweeps with an net (38-cm diameter) above the head and shoulders. After the first 5 sweeps, a Simulium bonaerense represented 79-89Vo of tl;ie 15-sec pause allowed the flies to regroup. The same larvae in treated waterways and S. wolfrhuegeli the individual (E.W.G.) dressed in navy blue shirt and remaining lI:2l%o. In addition to the canal and pants performed all sweeps. drainage system, all 3 rivers (Limay, Neuquen, and The initial test was conducted in Canal VI. The Negro) provided larval habitat, although the Limay B.t.i. (4.9 liters) was diluted with an equal amount River had low larval populations (<15 larvae col- of water to enhance mixing, and the mixture was lected/min) upstream of the City on Neuquen. Lar- applied from a 10-liter watering can at a dose of vae of all 3 pest species (5. bonaerense, S. woffi 12.4 ppm. The application was made over a l-min huegeli, ard S. nigristrigatum) were present in the period, 5 m downstream of a water-control structure Limay River, and 84Vo were ,S. bonaerense. The where turbulence aided mixing. Mortality evalua- Negro River near the town of Pomona City had populations (>50 tions in Canal VI were conducted to a distance of heavy larval larvae collected./ min), with S. bonaerense prevalent species 3,850 m downstream of the treatment site. Samples the most (97Vo). also were collected below 2 sets of water-control Adult monitoring indicated that S. bonaerense structures to determine how B.r.i. would flow was the most important biting species. All but I of through these structures that are integral to the ir- 143 females captured were of this species; 1 female rigation system in this region. At 1,100 m below of S. woffiuegeli was captured. An average of 15.9 the treatment site, approximately 0.5 m3/sec of wa- females (range: 6-28) was collected in 9 samples, ter was diverted to a secondary canal. At 1,880 m with wind speeds ranging from 1.6 to 29.0 km/h. from the treatment site on this secondary canal, a Female numbers were well above those warranting 2nd set of water-control structures subdivided the suppression programs in North America (Gray et flow and reduced it to approximately O.25 m3/sec. al. 1996). In addition, the biting, as opposed to nui- On February 20, Canals Vtr and VIII near the sance, activity of S. bonaerense makes these levels ppm town of Lamarque were treated at 5.0 for I less tolerable. min and at 4.5 ppm for 1 min, respectively. Both of these applications (B.r.i. diluted with equal amounts of water) were made with a 10-liter wa- B.Li. treatments tering can from a water-control structure into an The irrigation system in the Negro River Valley area of turbulence. On February 25, tlre Rio Salado is composed of a series of water-control structures near the town of Darwin was treated at 25 ppm for that continuously divides the flows until the irri- 1 min, with a 20-liter container, while crossing the gation water reaches its final destination. It was, cuffent. On February 26, Drainage Plottier was therefore, crucial to test whether the B.t.i. provided treated at 25 ppm for 1 min in an area of swift flow effective larval mortality below the water-control below a water-control structure. structures. In Canal VI, the B.t.i. moved through SePTeN{een1999 Blecr Fr-y MANAcEMENT n AncnNrtNe 403

the initial water-control structures and provided ef- were conducted to 3.2 km from the center of the fective mortality (>9OVo) at distances of at least treatment zone, and adult levels were reduced by 3,00O to 3,500 m (Thble 2). High larval mortality 86Vo at the center. Extensive time and effort were in Canal VI demonstrated the stability and longev- required to treat small (discharge <0.5 m3), not ity of the Vectobac even though it was 5 months readily accessible waterways, adding significantly beyond its use-by date. to the cost of the management program. The use of 5.0 ppm of Vectobac AS did not pro- In 56o Paulo, Brazll, the primary pest species (,S. duce effective larval mortality in Canal VII (Table pertinax Kollar) developed resistance to temephos 2). Larval mortality in Canal VIII, although not as (Neto 1984), and biological control with B.r.i. was high as necessary for an adult suppression program, implemented. In 1992, 1,456 breeding sires were indicated the excellent carry potential of the canal targeted to reduce adult levels to acceptable limits system. At 4,7OO m below the treatment site,i4.3Ea during peak tourist season (January-March) (Ar- mortality was achieved with a dose of only 4.5 aujo-Coutinho 1995). Using the reported monthly ppm. Why higher levels of mortality were not dem- figure of $48,904 and an average of 6 months/year, onstrated at closer evaluation sites is not knownl we projected a cost of $293,426/year to protect the more testing is required to determine an effective affected area (893 km,). dosage under these conditions. Recent expansion of the management program The Rio Salado will pose a challenge to a black for Simulium jenningsi Malloch in Pennsylvania fly suppression program. This waterway is approx- makes it I of the largest in the world. Twenty-eight imately 70 km long and contains areas of larval of Pennsylvania's 67 counties treat the breeding habitat interspersed with pools and dense aquatic waters of this pest, with a major focus on the large vegetation. Aquatic vegetation reduces the carry of Susquehanna River. The total budget for the pro- B.t.i. by lengthening the water path and increasing gram in 1997 was approximately $3.75 million. In the surface area to which the water column is ex- 1995, the year for which the most accurate infor- posed (D. Kurtak, personal communication). None- mation is available, control costs were about $89/ theless, our tests showed that effective larval con- km' (D. Arbegast, personal communication). Adult trol could be achieved at reasonable distances in monitoring is conducted regularly with a technique areas with adequate flow (Table 2).Larval samples similar to that of Gray et al. (1996). Monitoring collected at 2,2O0 and 2,350 m indicated rhat some sessions capturing l0 or more adults indicate a need material moved through the 700 m of unsuitable for addilional larval suppression. larval habitat upstf,eam of these sites. This area in- The South Salt Lake County, Ul Mosquito cluded deep pools and 100 m of dense aquatic veg- Abatement program used Vectobac 12AS in irri- etation. gation ditches and natural waterways to suppress At Drainage Plottier, larval mortality was satis- Simulium vittatum Zetterstedt cytospecies IIIL-1 in factory (>9OVo) through l,2OO m ltable Z;. Stow 199'7 (K. Minson, personal communication). In flow and increasing volume probably contributed to nearby northern Nevada, the average cost to sup- the drop in mortality beyond 1,500 m. An important press black flies (primarily Simulium meridionale consideration in treating drainage channels is that Riley), using methoxychlor and limited B.t.i. appli- the flow volume increases with distance from the cations, was $70lkm, (R. D. Gray, personal com- treatment site. This trend also applies to most riv- munication). This figure is based on the distance of ers, but the smaller flow volumes of the drainage river treated and a 3.3-km band on either side of systems make the percentage of increased flow a the river, the distance at which signif,cant nuisance more significant factor. In the future, flow should levels were observed. In 1992, a low-flow vear be measured at the farthest downstream site where when only B.r.l. was used, the average cost in 2 effective control is to be achieved. This procedure counties was g30/krnr. The difference between low- will expose larvae at the downstream site to the and high-flow years demonstrates that the volume target dose and not underdose them, as in this trial. of water treated is a major determinant of costs for a management program. Flexibility, therefore, must Comparisons with related programs be preserved when determining budgets and the amount of insecticide required. Reduced larval The cost of developing a suppression program mortality after applications of methoxychlor in late for the Negro River Valley is an important issue for 1997 and early 1998 suggests thar resistance to this the government of Argentina. Costs of other black chemical has developed. Increased use of B.t.i. is fly management programs can provide insight into expected. this matter (Table 3). Although adulticiding is an Colbo (1985) developed a management program effective technique .Wa- for mosquito suppression, it is in the Labrador City-Wabush area of Canada. not a cost-effective means of reducing black fly terways in the area had flows of 0.2 to 19.2 mi/sec populations. In the Adirondack Mountains of New and were treated 4 times during the program. This York, larvicide applications g400/ required about program had a proposed goal of at least SOVo re- km2 in the lst year, with $240-380/km2 for subse- duction in adult levels and a treatment radius of 10 quent years (Molloy and Struble 1989). Treatments km. Jouwer- oF THE AMERtceN Mosquno CoNrnoL AssocrarroN Vol. 15, No. 3

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The Metropolitan Black Fly Control Program The cost of a black fly suppression program de- (MBCP) in St. Paul-Minneapolis, Minnesota, op- pends on several factors, most of which are related erated on a budget of $218,000 (Simmons and Sjo- to the ecology of the pest species. One factor is the gren 1984) or $48/km' of area protected. The frequency of larvicide applications relative to the MBCP is part of the Metropolitan Mosquito Con- generation time of the pest species. Colder waters trol District, capitalizing on the insect-control in- produce fewer generations and require fewer lar- frastructure already present in the area. The cost for vicide applications. Programs targeting the multi- the program in 1997 dropped to $39/kmr, with a voltine members of the S. jenningsi species group total budget of $179,600 (J. Sanzone, personal typically require 10 to 15 treatment sessions, re- communication). The 1997 program monitored ap- gardless of location (E. Gray, unpublished data; D. proximately 150 sites on small to mid-size streams Arbegast, personal communication; Smithson for the Simulium venustum Say complex and 24O 1996). The flight range of the pest species is also km of large rivers (Mississippi, Minnesota, Rum, important in determining the size of the proposed and Crow rivers) for Simulium luggeri Nicholson program. For strong flying species (e.g., members and Mickel, Simulium johannseni Hart, and S. mer- of the ,S.jenningsi species group), large areas must idionale Rlley. be treated to avoid immigration from outside the The West Virginia Division of Environmental treatment zone. Prosimulium species, conversely, Protection treats a 48.3-km radius (7,332 kmr) are not such strong fliers, allowing smaller treat- around the city of Hinton, West Virginia, targeting ment zones. Prosimulium species typically inhabit S. jenningsi, with a 1997 budget of approximately smaller waterways, increasing the cost of black fly $250,000 (J. Smithson, personal communication). suppression for 2 reasons. First, the carry of B.t.i. Based on the area protected, this program is cur- is less in waterways with less flow, requiring treat- rently the 3rd largest in the world. The Kentucky ments at shorter distance intervals. Second, acces- Department of Agriculture has a single treatment sibility often becomes a problem as the number of period during mid-January in 5 counties, targeting treatment sites increases. the univoltine Cnephia pecuarum (Rlley). This pro- Additional developmental work is needed in Ar- gram has an estimated budget of $32,680 (M. Buhl- gentina. For example, little is known about the ig, personal communication). flight range of the primary pest, S. bonaerense. We, The Onchocerciasis Control Programme (OCP) therefore, are not certain what percentage of the in the Volta River Basin of West Africa-the larg- valley would require protection. Howeveq because est vector-control program in the world-manages the canal system is constantly monitored and ad- black flies over 764,0O0 km, at a cost of approxi- justed, treatment and evaluation of canals would be mately $20 million (Philippon 1988). This program easy. In addition, warm water and high flow rates uses chemical and biological control agents, de- characteristic of irrigation canals are conducive to pending on seasonal flow levels. The level of re- B.t.i. efficacy. If the entire valley requires treat- duction for disease vectors is far more critical than ments to reduce adult levels, the program would in nuisance situations where low pest populations become the 3rd largest in the world, on a km2 basis, can be tolerated. The OCP program, therefore, de- after the West African and Pennsylvania programs. mands the highest standards for larvicide effective- Comparing the costs of various management pro- NESS. grams on a cost/km2 basis provides a means of es- In South Carolina, the primary pest species timating possible costs in the Negro River Valley. (members of the S. jenningsi species group) inhabit As a point of reference, projecting the costs of the large streams and rivers in the treatment area, with Sdo Paulo project to the entire area of the Negro the primary waterways having flows of 8 to 14 m3/ River Valley (18,240 kmr) yields a program costing sec (Gray et al. 1996). Members of the S. jenningsi approximately $6,000,000/year. However, the canal species group are strong fliers (Choe et al. 1984), structure and size of the Argentine program should necessitating a treatment radius of 1O km or greateL be more conducive to cost-effective larval control After 3 years of work, the program was expanded than the area in Brazll. Extrapolating from the to an 18-km radius, with development costs spread Pennsylvania program places the cost at about over this period. Adult levels were reduced by 97Vo $1,623,360. The potential size of the program and in 1998 compared with preprogram counts (E. need for governmental involvement make this es- Gray, unpublished data). The large, warm (18- timate reasonable. If it is necessary to treat the 25'C) streams and rivers inhabited by the target large rivers (Limay, Neuquen, and Negro) in the species are conducive to maximum carry and effi- Negro River Valley plus the irrigation system, the cacy of the B.t.i. product, which contributes to low- comparison with the Pennsylvania program might er program costs. The good carry in larger rivers be the most accurate. Based on South Carolina flg- allows treatments and dosages to be adjusted for ures, the cost of black fly suppression in the Negro applications at easily accessible points. In addition, River Valley would be $383,040. Although the the of the pest species was resolved prior South Carolina program is a 2-person operation, to initiation of the program (Moulton and Adler several factors make the estimate reasonable. Tax- 1995). onomic work has been conducted in the Neero Riv- 406 JoURNAL oF THE AMERTCIN Mosqurro CONTRoL AssocrATroN VoL. 15, No. 3 er Valley, the pests have been identified, and rele- S. Krause. This is technical contribution no. 4436 vant larval habitats have been located. Because of of the South Carolina Agricultural Experiment Sta- the small volume of B.t.i. used in South Carolina, tion, Clemson University, Clemson, SC. standard distributor pricing is used. The large vol- ume of B.t.i. that would be required in the Negro REFERENCESCTTED River Valley might offset the additional distribution Araujo-Coutinho, C. J. P C. 1995. Biological control pro- costs for international work through bulk purchas- gram against simuliids in the State of 56o Paulo, Brazil. ing. Finally, the cost of quality labor in this region Mem. Inst. Oswaldo Cruz 90:131-133. of Argentina should be less than in the United Choe, J. C., P H. Adler, K. C. Kim and R. A. J. Taylor. States. To project the cost of any black fly sup- 1984. Flight patterns of Simulium jenningsi (Diptera: pression program, the delivered cost of the insec- Simuliidae) in central Pennsylvania, USA. J. Med. En- ticide and operational costs must be included in the tomol. 2l:474-476. final figure. In addition, large-scale suppression Colbo, M. H. 1985. Development of a field protocol for projects require substantial technical infrastructure ground application of Bacillus thuringiensis var. israe- lensis as to be implemented and operated effectively. a black fly larvicide in northern Canada. Final report for DSS contract 8SU82-O0283. Future work will require additional evaluation of Coscar6n-Arias, C. 1997. Estudio bioecol6gico de Simu- larval black fly populations in the rivers of the Ne- lidos (Jejenes) en las provincias de Neuquen y Rio Ne- gro River Valley. Because the cost of treating rivers gro para la determinaci6n de m6todos de control ra- of this magnitude will be substantial, we targeted cional. Convenio AIC-FUNYDER 1997. the smaller, more workable larval habitats as an ini- Gray, E. W., P H. Adler and R. Noblet. 1996. Economrc tial step in developing a management program. Our impact of black flies (Diptera: Simuliidae) in South Car- trials represent the beginning of the task of delin- olina and development of a localized suppression pro- eating the carry characteristics of all breeding sites gram. J. Am. Mosq. Control Assoc. 12:676-678. Horosko, S. and R. Noblet. in the region. The basic structure of the canal sys- 1986. Local area control of black flies in the Southeast with Vectobaco-AS and tem, however, should enable effective treatment of Vectobac@-l2AS. Agric. Exp. Sta. Bull. 658:1-9. the waterways. In South Carolina, effective control Molloy, D. P and R. H. Struble. 1989. Investigation of (>95Vo mortality) can be achieved in natural river the feasibility of the microbial control of black flies systems (6-14 mr/sec) for over 10 km. Excellent (Diptera: Simuliidae) with Bacillus thuringiensis var. is- carry in irrigation canals is evident from our trials. raelensis in the Adirondack Mountains of New York. Considering the size, economic-impact potential, BuII. Soc. Vector Ecol. 14:266-276. and benefits of a black fly management program in Moulton, J. K. and P H. Adler. 1995. Revision of the j the Negro River Valley of Argentina, rhis srudy Simulium enningsi species-group (Diptera: Simuliidae). Tians. Am. Entomol. Soc. 121:1-57. should provide some useful perspectives to the sci- Neto, A. L. R. 1984. Avaliacao do uso de temephos para entiflc and business communities of both North and o controle de simulideos no Rio Grande do Sul. B. Sau- South America. de ll:27-31. Philippon, B. 1988. Problems in epidemiology and control of West African onchocerciasis, pp. In: K. ACKNOWLEDGMENTS 363-3'73. C. Kim and R. W. Merritt (eds.). Black flies: ecology, pop- We thank Autoridad Interjurisdiccional de Cuen- ulation management and annotated world list. Pennsyl- cas de los rios Limay, Neuquen, and Negro for sup- vania State University, University Park, PA. Simmons, K. R. and R. D. Sjogren. 1984. Black fly (Dip- porting this work, including an on-site visit by tera: Simuliidae) problems and their control strategies E.W.G. We also gratefully acknowledge the infor- in Minnesota. Bull. Soc. Vector Ecol. 9:21-22. mation provided by D. Arbegast, M. Buhlig, R. D. Smithson, J. E. 1996. A report on the 1996 Black Fly Gray, D. Kurtak, K. Minson, J. Sanzone, and J. Control Program. Division of Environmental Protec- Smithson and the assistance of J. W. Amrine and tion. Nitro. West Virsinia.