MOSQUITO VECTOR CONTROL and BIOLOGY in LATIN AMERICA a THIRD Symposrum'

Journal of the American Mosquito Contol Association,9(4\:441453, 1993

MOSQUITO VECTOR CONTROL AND BIOLOGY IN LATIN AMERICA_A THIRD SYMPOSruM'

GARY G. CLARK',CND MARCO F. SUAREZ (ORGANIZERS)

San Juan laboratories, Centersfor Disease Control and Prevention 2 Calle Casia, San Juan, PR 00921-3200

ABSTRACT. The third Spanish language symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 59th Annual Meeting in Fort Myers, FL, in April 1993. The principal objective, as for the symposia held in l99l artd 1992, was to increase and stimulate greater partlcipation in the AMCA by vector control specialists and public health workers from l:tin America. this publication includes summaries of 25 presentations that were given in Spanish by participants from 8 countries in Iatin America, Puerto Rico, and the USA. The symposium included the following topics: ecological, genetic, and control studies of anopheline vectors of malaria; laboratory evaluation and pro-- duction of biological control agents for Aedes aegypti) community participation in the prevention of dengue; and studies of other medically important insects (e.9., Simulium and Triatoma).

The American Mosquito Control Association continues to be very good. Special recognition (AMCA) is the leading organization of its kind for generousfinancial support for the I 993 sym- in the world. The AMCA promotes research, posium goes to the following sponsorsand in- neededto understandmosquitoes and other vec- dividuals: Vectec,Inc. (IsaacS. Dyals); the Flor- tors and for control ofthese arthropods by pro- ida Mosquito Control Association (T. Wainwright fessionals.In 1993, a Spanish languagesympo- Miller, Jr.); ZENECA Public Health (Dr. Julian sium was held at the 59th Annual Meeting in Ft. C. Entwistle); Clarke Mosquito Control Products Myers, FL. This session was held becauseof the (John L. Clarke, Jr.)i Taecon, Inc. (Miguel E. enthusiastic participation of vector research and Escobar); Summit Chemical Company (Iaw- control workers from government agencies and rence E. Kase); Beecomist Systems, Inc. (Ed academic institutions in Latin America, the fi- Kutzner); and Sumitomo Chemical America (S. nancial support of commercial sponsors,and the Ohtsuki). This support provided for registration successof similar sessionsheld in New Orleans. fees, partial travel grants to some participants, LA, in l99l and in CorpusChristi, TX, in 1992. and simultaneoustranslation. Mr. Dennis Moore As in prior years,general objectives were to en- provided superb assistance in arranging for the courage colleaguesfrom Latin America to attend translation service and the registration commit- the AMCA meeting, present results of recent teewas very helpful to international participants. studiesand projects,promote greaterinteraction Funds for the publication of this symposium with AMCA members, and stimulate future col- were provided by the Rockefeller Foundation laboration in the resolution ofvector-borne dis- (Dr. Scott B. Halstead) and ZENECA Public easeproblems in the Americas. Health (Dr. Julian C. Entwistle). As a result of Becauseofthe popularity ofthis session,it was the positive response from participants and the not possible to include all of the presentations AMCA leadership,this unique forum will be in- that were submitted to the organizersofthis ses- cluded in future AMCA meetings. sion. As it was, an entire afternoon was devoted to 25 high-quality presentationsthat were made SYMFOSIUM ABSTRACTS in Spanish. Simultaneous translation was provided for personswho attended the program but A study of human factors considered relevant to did not understand Spanish.The enthusiasm of the transmission and control of malaria in two the speakers,spirited discussion,and attendance villages in ffonduras (Estudio de los factores ensuredthat the symposium onceagain achieved humanosconsiderados relevantes en its objectives. la transmisi6n y el control de malaria en The support of AMCA members for this unique dos pueblosde Honduras) and innovative sessionat the Annual Meeting J. C. Stivers and L. A. Rivera University of South Carolina, School of ' Presontedatthe 59tlAnnual Meetingofthe Amer- Public Health, McClellanville, SC, USA and ican Mosquito Control Association, Fort Myers, FL, Ministerio de Salud de Honduras, Tegucigalpa, on April 20, 1993. Honduras 2 Reprints may be requested from Gary G. Clark, Dengue Branch, CDC, 2 Calle Casia, San Juan, PR A study was performed in Guapinol and Sinai, oo92r-3200. Honduras, in 1986 to determine which human 442 Joup.r.rer or nre AvpnrceN Mosqurro Covrnor Assocre,rroN Vou 9, No. 4

factors might be relevant to the transmissionand We studied I nophelesdarlingi at the Fernando control of malaria. The study consisted of the Azcona estate, La Ceiba, Atlandida, Honduras administration of a questionnaireto village res- (15"44'24'N, 86"5l'36'W). Mosquitoeswere idents, observations of the living environment captured with human bait and marked with "Dayglo" of the residents,and a blood survey to determine fluorescentpowder. After release,at- malaria prevalence. tempted recapture of marked mosquitoes used In Guapinol, 389 personsliving in 74 houses human bait. In the laboratory, specieswere iden- participated in the blood survey,which identified tified, abdominal appearancewas recorded,and 3l individualsin 2l housespositive for malaria. ovaries were dissectedto determine the physi- In Sinai, 436 personsresiding in 72 houseswere ological age and follicular development. These sampled, with 8 people in 7 housesbeing iden- activities werecarried out between1830 and 2330 tified as positive for malaria. Of the 406 indi- h bimonthly for 6 consecutive days from May viduals surveyedin Guapinol, 46 residing in 28 26, 1989,to May 23, 1990.Of | 1,332Anopheles housesreported a laboratory-confirmed caseof albimanw and 10,187An. darlingi marked, l.l malaria during the preceding 3 years. In Sinai, and 1.37oofthese species,respectively, were re- thesefigures were 437 individuals surveyedwith captured.A significant correlation was found be- 46 previous casesin 27 houses. tween the abdominal appearanceand follicular The information gathered during the survey development for both An. albimanus and An. was analyzed using chi-square to determine if darlingi (x' : 3.58,P < 0.05, df : l; x2 : 4.0O, there was an associationbetween current or past P < 0.025,df : I, respectively).In both species, malaria infections and human habits. The fol- we found that the nullipars had bloodfed 2 or lowing factors were found to be associatedwith more times within the gonotrophic cycle. For either current or past malaria infections at P < both species,the duration ofphase 2 ofthe gon- 0.05. In Guapinol, current infections were as- otrophic cycle was 60.4 + 2O.4h, with a maxi- sociated with the number of inhabitants per mum for the first cycle of 120 h. The second house,with individuals in houseswith more than gonotrophic cycle beganwith the appearanceof 5 residentsbeing at increasedrisk. In Sinai, cur- Christophers' second stage. rent infections were found to be associatedwith an individual's sex,wakeup time, and a previous history of malaria infection. Males, individuals Population dynamics of Anopheles sp. from malaria with a wakeup time before 0400 h, and individ- endemicareas of coastal Colombia (Dinirnica poblacion uals with a previous infection were found to be de lle Anophelessp. de zonas at increasedrisk of malaria infection. In Guapi- costerasend6mica de malaria nol, age group, evening habits or location, oc- en Colombia) cupation, length ofresidence in the village, and R. Valderrama, S. Franco, S. Blair, M. F. Su6rez, per number of inhabitants housewere associated L. Osorio, M. C. Correa and O. Gallo with a history of malaria. Individuals in the age group of 5-14 years, people with mixed indoor Depart ame nto de Microbiologia y Parasit ologia, and outdoor evening activities, students,people Facultad de Medicina, Universidad de with lessthan 2 years of residencein the village, Antioquia y Semicio de Erradicacidn de and individuals living in houseswith more than la Malaria, Medellin, Colombia 5 inhabitants were at a higher risk of having a history of malaria. A history of malaria was as- We analyzed ecological aspects that affect the sociated with evening habits or location, length distribution and population dynamicsofthe most of residence in the village, and number of in- important vectors in a malaria-endemic areafrom habitants per house in Sinai also. The specific coastal Colombia. The objectives were to iden- g,roupsat risk were the same as those in Guapi- tify local speciesand their distribution and den- nol. sities in macro- and micro-ecological habitats, and determine how several ecological variables Observationson the gonotrophic cycle of affectedtheir population dynamics. anophelines(Diptera: Culicidae) in Honduras The area was categorizedaccording to land- (Observacionessobre el ciclo gonotrofico use practices,type of soil, elevation, air temper- de an6felesde Honduras) ature, relative humidity, type of hut (percentage ofwall protection that preventsthe mos- L. Rivera, D. Canalesand M. Nelson entry of quitoes), and number of inhabitants per dwell- Divisidn E nfermedadesTransmitidas por ing. Anophelines were collected between 1800 Vectores,Ministerio de Salud, Tegucigalpa, and 2400 h with indoorand outdoorhuman baits H onduras and Organizaci6n Panamericana and from restingsites inside the hut. The number de la Salud, Panamd of anophelinesper dwelling per day (ADD) and Drcnr,snn 1993 Moseurro Veqron Svvposruu 443

the number of anopheline per dwelling per year anophelines were kept dry over silica gel until (ADY) were calculated. assayedby ELISA. The human and domestic During one yearofstudy, 3,356adult anophe- animal populations in the villageswere censused. lines were collected from 44 dwellings near the The feeding index (FI) (i.e., the observedpro- Uraba Gulf on the Atlantic coast.Anopheles al- portion offeeds on one host with respectto an- bimanus and Anophe les nuneztovari represented other divided by the expectedcomparative pro- 70oloof the collections and l9olowere Anopheles portion offeeds on the 2 hosts [Kay et al. 19791) punctimacula, Anophelespseudopunctipennis, and was calculatedfor the 4 most common species: Anopheles darlingi, all important malaria vec- Anopheles nuneztovari, Anopheles t riannulatus, tors. The remaining I lolowere other anophelines Anopheles oswaldoi, and Anopheles albitarsis, with minor or no epidemiological importance as based on the results of the ELISAs and ques- malaria vectors.The distribution of anophelines tionnaires. and their population dynamics were different in The FI was found to be different for each spe- the 3 ecological subzones(littoral, hills, and in- cies in each village. In Guaquitas, where there termountains).The ADD in the littoral areaswas were 487 bovines arad44 people, the FI for all greater than in the intermountain subzone.The 4 specieswas higher than 1.0 (i.e., there was ap- largest ADY was found in the intermountain parently preferential feeding on humans). These subzone(ADY : I l9), whereasthe ADY in the results contrast to those in Jabillos where there littoral was 74 and in the hills was I 5. The ADD werc 282 bovines and 303 people and whereln. was similar to the ADY in these subzones.The nuneztovari,An. albitarsis, and An. triannulatta' percentageof unprotected dwellings was above apparentlyfed preferentially on bovines. In Caflo 40 but below 60 in subzoneswith higher ADD. Lindo (320 bovines and ll4 people),An. nu- The averagenumber of inhabitants per dwelling neztovari and An. albitarsis fed preferentially on was 5. The outdoor collections of anophelines humans. The contrasting results obtained in these yielded 850/oof the total. These findings reflect a villages may be explained by the larger number high risk for the transmission of malaria in this of cows belonging to the inhabitants of Guaqui- area. tas and Caflo Lindo, kept closer to where the mosquitoes were collected than at Jabillos.

Feeding index of anophelinesin western Venezuela(Indice de alimentacion de Predictive analysis of Anopheles triannulatus anofelinos en el occidentede Yenezuela) abundancein western Yenezuela(Anilisis predictivo de la abundanciade Anopheles Y. Rubio-Palis, C. F. Curtis and R. A. Wirtz triannulatus en el occidentede Venezuela) Divisi6n de Investigaciones, Escuela de M. Oviedo and J. V. Scorza Malariologia y SaneamientoAmbiental, Centro Trujillano de I nvestigaciones "J. Venezuela;Department of Medical Parasitol6gicas W. Torrealba," Parasitology, London School ofHygiene and Trujillo, Venezuela Tropical Medicine, London, UK; and Depart ment of E nto mo logy, For 2 consecutive years, the abundance and Walter Reed Army Institute of Research, indoor and outdoor human biting activity of Washington, DC, USA Anophelestriannulatus was studied monthly between 1990 and 22OOh in western Venezuela The tendency to feed on human blood is a (9'34'N, 7O"37'W).The population of An. trian- useful indicator in determining the relative im- nulatus increasedwith a rainfall of 100 mm dur- peridomiciliary portance of Anophelesspecies as vectors of ma- ing the first half of the year and peaked laria. Thesefeeding patterns could also be useful biting activity between I 900 and 2000 h. Measurements of temperature, relative hu- in the epidemiological assessmentof control ac- midity, and pluvial rainfall were compared with tivities as a comparative measureof the effectof local meteorologicaldata obtained from a station residual insecticideapplications upon the degree located 2 km from the study site. Regression of contact between vector and man. analysis and multiple stepwise regressionwere To assessthe feeding patterns ofanophelines used to compare the biting rates of An. trian- in a vivax malaria endemic areain westernVen- nulatus with the accumulated rainfall: discrim- ezuela,mosquitoes resting on vegetationin 3 vil- inating betweenstrong (PF) and weak rains (PD), lages were collected with an aspirator between taking into account ifthey were above or below 0600 and 0800 h, 4 days per month at each vil- the annual average; the rainfall on the day of lage for 14 months. After speciesidentification, capture (PC); ifrainfall occurred the day before 444 Jounr.ter or nrn AurnrclN MoseulTo Covrnor, Assocrro^rror.t Vor.9,No.4

the capture(PA); the relative humidity (HR); and Larvat ecology of the malaria vector, temperature (T"C). Anophcks pseudopunc'tipennis,in the foothills area Multiple regression analysis showed the pos- of Tapachula, southern Mexico (Ecologia de las sibility of predicting with a 76Yoreliability (P : larvas del vector de malaria. 0.05) the number of mosquitoes that bite ac- Anophelespseudopunctipennis, en el area de las cording to the following regression equation: colinas de Tapachula al sur de M6xico) number of mosquitoes: 243.6 + 0.52619PC - 2.644T"C- 4.4373pD- 5.8526pF- 1.2608HR I. Fern6ndez-Salas,D. R. Roberts, M. H. - 4.6661P4 + O.2O23PP.The multiple stepwise Rodriguez and C. F. Marina-Fern6ndez regression suggestedthat under weak precipita- Universidad Aut6noma de Nuevo Le6n, tion conditions, with a reliability of 88% (P : San Nicolds de los Garza, M6xico; 0.05), the number of mosquitoes that will bite Department of Preventive Medicine and follows the following equation: number of mos- Biometrics, Unifurmed Services Universily of -81.5 quitoes: + 5.244PD.This last equation Health Sciences,Bethesda, MD, USA: needs to be confirmed under field conditions. and Centro de Investigaci6nes de Paludismo, Tapachula, M€xico A study of the population dynamics of Anoph- elespseudopunctipennis lawae was conducted in A study ofthe genetic structure ofa population the foothills near Tapachula,Mexico. Systematic of Anopheles nune4,tovari(Estudio sobre la surveillance of wet seasonand dry seasonhab- estructura gen6tica ile Anopheles nuneztova$ itats was conductedin 1990and l99l . Samples were taken along a transect of the Coatan River Y. Rangel and L. E. Munstermann to quanti& habitat availability and population Universidad Central de Venezuela, Caracas, densities of larvae during the dry seasonfrom Venezuelaand Yale University School of December to May. During the wet season(July- Medicine, New Haven, C7', USA November), larvae were most abundant in temporary habitats, such as seepagesprings (25%), Anopheles nuneztovari is the main malaria rain pools ( I 5%),and pools in streams( I 5%) and vector in western Venezuela and northern Co- river margins (15%). These transitory habitats lombia. Some authors have suggestedthat An. produced more than two-thirds (70%) ofthe lar- nuneztovari is a sibling speciescomplex, based vae collected during the wet season.The tem- on cytogeneticstudies, biting activity, and med- porary habitats disappeared during the dry sea- ical importance. The objective of this study was son, concrulent with increasing densities oflarvae to expand earlier isozyme analysesof An. nu- in habitats within the transect. The great abun- neztovari by examining l8 loci from 5 popula- dance of the dry season riverine habitats, viz-, tions in its geographical range. Three of these small pools with filamentous algae, resulted in populations were from [.a kngueta de Barinas peak densities of host-seekingadult populations (western Venezuela, southern Cordillera de los in villages along the river. During both seasons, Andes). One was from [,a Fria (northern Cor- there weresigrrificant associations in the presence dillera de los Andes) and the last was from Be- and abundanceof larvaewith habitatscontaining lem, Par6 State, Brazil. filamentous 6lgae,and secondarily with aquatic The 3 populations from I-a Lengueta de Bari- and semiaquatic plants. There was a significant nas showed little genetic differentiation, as in- correlation between mean number of larvae per dicated by the Fisher's F-statistic (F[ST]) of 0.023. habitat type and mean number of breeding sites Only the electromorphs of hydroxyacid dehy- in the transect.Overall, populations of An. pseu- drogenase (HAD) differed significantly from a dopunctipenrui larvae were very abundant dur- Hardy-Weinberg equilibrium. The La Fria pop- ing the dry seasonand relatively uncommon dur- ulation had striking differencesat the malate de- ing the wet season. hydrogenase(MDH) locus, although the overall F(ST) of 0.066, with respectto the La Lengueta Pilot production oI Bacillus thurtngiensis vsr. populations, was low. The sample from Brazil israclensis using whole coconuts and field was genetically distinct, including a diagnostic applications for biological control of allele at the glycerol dehydrogenase(GCD) locus Anopheles in malaria endemic and high frequency differences with MDH and areas of Peru (Produccion piloto usando HAD isozymes.These were reflected by an F(ST) cocos completos y aplicaci6n en eI campo of O-432.The high degreeofdifferentiation across Bacillus thuringiensis var. israelensrlspara el the range of An. nuneztovari indiates that it is conhol biol6gico lle Anopheles en ireas a complex of cryptic species. end6micas de malaria en el Peru) DecarDER 1993 Moseurro Vpqron Svr,posruu 445

P. Ventosilla, C. Ruiz de Somocurcio, H. Guerra, iciliary spray of lambda-cyhalothrin l0 WP was D. Marin and I. Columbus applied to 30 mg AUm2.In Cachipal, a similar "Alexander application of pirimiphos-methyl 50 EC was Instituto de Medicina Tropical von " made at 2 g Allm'. In de la Nifra, ULV Humboldt, Universidad Peruana Cayetano Quebrada space-spraysof lamMa-cyhalothrin 2.5 EC were Heredia, Lima, Perfi applied weekly at I g Al/haand in El Paujil, both About 56% of the world, 39% of the Latin an intradomiciliary application of pirimiphos- American, and37% of the Peruvian population methyl 50 EC at 2 g AUm2 and weekly space- are at risk to malarial infections. In Peru, malaria sprays of lambda-cyhalothrin 2.5 EC at I g AI/ is distributed in several endemic areas along the ha were carried out. World Health Organization coast and in the jungle. Despite increasedvector cone bioassaysand susceptibility testswere con- resistanceand ecological damage,insecticides are ducted. Human bait counts were also made on still the key tools for malaria control. Conse- a weekly basis, and mosquitoes were examined quently, the use of specific entomopathogens for for parity status- The number of malaria cases the control ofinsect vectors ofdisease is becom- reported was reduced in all 4 villages in com- ing increasingly attractive. Bacillus thuringiensis parison with the previous year. The reduction var. israelensisH-14 (B.t.i.), one of the better was greater in the 2 areas that received space known agents, acts through a cytolytic protein applications, and the most rapid decline of all produced during sporulation, which destroysthe was observed in El Paujil, which had received larval midgut epithelium. both treatment regimes. All the products tested We are developing a simple procedure to be were effective in reducing malaria, especially the used by rural communities for local production space-sprayapplications of lambda-cyhalothrin and application of B.t.i. using resourcespresent 2.5 EC. in malaria endemic areas. I-aboratory studies have demonstrated that artificial media and co- conut water, either in glass flasks or within the Statistical evaluation of the man-biting activity fruit, produced B.t.i- attllle same rate and yielded of Simuliam ochroceum to estimate Oachocerca the same total quantity. Toxic activity against volvulus transmission in a hyperendemic focus both 3rd and 4th instar Culex and Anopheles from southern Mexico (Evaluaci6n estadistica larvae was similar. Field trials showed the pres- de la actividad de picadura de enceofviable 8.1.1.spores in seedednatural ponds Simulium ochraceum para estimar la in endemic areasfor 2l days (Lima) and l8 and transmision lle Onchocerca volvulus, en un foco 25 days in warmer areas(Piura, Yurimaguas). hiperend6micodel sur de M6xico) The ability of local communities in endemic M. A. Rodriguez-P1rezand F. Reyes-Villanueva areas to control malaria through production and use of .B.t.i. appearsto be feasible. Centro de Investigaciones Ecol6gicas del Sureste, San Crist6bal de las Cases, Chiapas and Facultad de Ciencias Biol6gicas, Field evaluetion of pirimiphos methyl and Universidad Aut6noma de Nuevo Le6n, lambda

sample size required in collection days and hu- Triatomine surveyswere conductedin Mexico man baits, and to estimate the mean number of in I 985-89 and in 199l During the first survey, S. ochraceumfemales infected with O. volvulus 66 Triatoma gerstaeckeri (35 adults and 3l larvae. nymphs) and 14 T. lecticularia (6 adults and 8 The study was conducted at Las Golondrinas nymphs) were found. This infestation occurred village, Acacoyagua(14.8'N, 92.3W) at 800 m in 36 ofthe 46 householdssurveyed in the vil- elevation in the SierraMadre ofChiapas. Month- lages of Vaquerias, Huizachito, La Gloria. and ly collections were made from September 1990 Delicias. Entomological indicators reflected an to September1991. Each samplingincluded 8 infestation index, II : 48; density index, DI : days of collections using 2 human baits (com- 143;crowding index, HI : 300; dispersionindex, munity volunteers): one located in the center of DDI : 100; colonization index, CI : 50; and the village and the other in a coffee plantation natural infection index, NII : 36. The highest located 200 m from the village. Collections were NII for T. gerstaeckeriwas in Delicias (100) and made from 0800 to 1800 h, and only the black for T. lecticulariainl-a Gloria (50). These2 spe- flies that landed during the first 30 min of each cies are included in the list of triatomines that hour were caught. All S. ochraceurnspecimens serveas household vectors ofchzgas'disease in were dissectedimmediately and parity and O. Mexico. Our results support their role as poten- volvulus lawal stageswere determined according tial vectors of Chagas' diseaseand the need to to the method of Porter and Collins (1984). include assessmentof entomological indicators The sampling model of Gerrard and Chiang for better understanding of the epidemiology "presence-absence" of (1970), known as the meth- American trypanosomiasis. od, was applied to the data. This model is in- The purpose ofthe second survey was to de- dependentofthe spatial distribution pattern, and termine the speciesof triatomids present in l0 describes the relationship between the mean villagesof General Teran, Nuevo Leon, Mexico; number of S. ochraceun females infected with their entomological indices; seasonaldistribu- O. volvulus larvae by collection period (5-h in- tion; sex ratio; and degree of association with terval and 24-h period), and the proportion (p) human dwellings. The 2 speciescaptured were of collection periods positive for infected fe- T. gerstaeckeri ( I 92) and T. lecticularia (9). Tria- males. In this relationship, the number of days toma gerstaeckeriwas found in l0 villages (DDI and collection periods, as components of the : 80) and l5 households(II : 24); T. lecticularia samplesize, can be usedto expressthe collection was found in only 4 villages (DDI : 40) and 5 effort required to estimate the mean number of households(II : 5). The Trypanosomacruzi in- tllieO. volvulus-infectedfemales, or the infective fection rates were similar in both species(NII : females(with the L3 stage),at any statistical re- 28 and 33, respectively).The gxeatestnumber of liability level. individuals were trapped during the month of Forty-three days of collections with 2 baits June (90 T. gerstaeckeri and 2 T. lecticularia). yielded a daily mean of 0. 13 infective females Of 192 T. gerstaeckericollected, 124 (650/o)were (mean SE : 0.40). This transmission level was femalesand 68 (35olo)were males; only 8 female equivalent to P : 0. 13 in a preliminary sampling (88Vo)and I male (l lo/o)T. lecticulariawere cap- of 8 days, if there was one infective female (l/ tured. Both specieswere consideredas peridom- 8). This sample size can be used in an oncho- iciliary triatomids, adapted to human dwellings. cerciasiscontrol program with ivermectin, to as- Ofthese, l8l (9790)ofthe Z. gerstaeckeriand 6 sessthe transmissionlevel before and after treat- (670/o)of T. lecticularia were captured around ment. We suggest that 3 collections of S. human dwellings. ochraceumbe made. distributed in the 3 months ofthe year when O. volvulwtransmission is highest in the community. Survey of natural parasites of Culicidae of BuenosAires Province, Argentina (Encuestade parasitos en Culicidoe de la provincia de Distribution of triatomids in two villages from BuenosAires, Argentina) Nuevo Leon, Mexico (Distribucion de triatomineos en dos pueblosde J. J. Garcia, R. E. Campos and A. Macia Nuevo Le6n, M6xico) Centro de Estudios Parasitol6gicos y de Vectores L. C. Galaviz-Silva, C. Lara-Campos, (CEPAVE), La Plata, Argentina M. Ramos-Guerra and F. Segovia-Salinas A survey for parasites of culicids was con- Laboratorio de Parasitologia, Facultad de ducted in the southeasternsector ofa subtropical Ciencias Biol6gicas, Universidad Aut6noma de forest in Punta l-ara, BuenosAires Province. Ar- Nuevo Leon, San Nicolds de los Garza. MExico gentina. Mosquito populations were sampled DBcBr{sBn1993 MosQurro Vscron SYIraPosIuIra 447 weekly for immature stagesand every 15 days Larvae were placed into l-liter glass containers : for adults from August 1989to August 1991. filled with 750 ml of dechlorinated water (pH Larvae and pupae@: a8,212)of 19 culicid 6.5) and each predator was exposedto l0 larval specieswere examined for parasites. Fourteen densities. In a second experiment, the predator culicid specieswere infected and parasitized by: and Bactimos at the recommended dosage(9.3 4 speciesof fungi (Achlya sp., Coelomomycesre- g/m2) were added. The number of prey con- ticulatw. Geotichum candidum, and Smittium sumed was recorded after a 24 h period, using 5 morbosum\; microsporidia of the genus Am- repetitions per density. Both treatments were blyospora;and a mermithid nematode, Strelko- conducted at a 14:l0 h light : dark photoperiod, vimermis spiculatus.Infection rates of thesepar- with an average temperature of 24"C. Results asites over the 2-year study were 260lofor ^1. were analyzed with a linear regression for the spiculatus, l2o/ofor S. morbosum. and less than first bioassayindicating that Y: 1.83571 + l.5olofor the other 3 parasitescombined. Higher O.532O4X,for the lst and 2nd instars, whereas prevalence of parasitism occurred during the for the 3rd and 4th larval instars Y : 2.01544 spring and fall months when host populations + O.42144X. Using Holling's functional re- were also high. Infectiorswith Amblyospora spp., sponseequation, a searchingcapacity of (a') : C. reticulatus, and S. spiculatus were lethal for 0.034155,and a handlingtime of (th) : 0.23999 host larvae; in contrast, S. morbosum caused were determined for lst and 2nd instars; and a' death in some hosts but not in others. Presence : 0.02589,th : 0. I 6460 for 3rd and 4th instars. of G. candidum was never related to the death On the other hand, using Rogers'sequation, re- ofthe host larva. sults were a' : 0.081822,th : O.442O5for the Female adults of 36 speciesof culicids were lst and 2nd instars, and a' : 0.05348, th : collected; however, only the 6 most abundant 0.44796 for the 3rd and 4th, respectively.Com- species(n: 3,357) were examined for parasites. bined linear regressionfor the predator and Bac- Resting sporangia of Coelomomycessp. (0.4olo) timos indicated Y: 0.35253 + 0-98374Xarld and haplosporidian-like spores(0.29Q were found Y: 1.8256+ O.7546lXforthelstand2nd, and in ovarian tissueofadults. Femalesinfected with the 3rd and 4th instars, respectively;with Holl- Coelomomycessp. showed a massive destruction ing's equation,a' :0.03813, th : 0.03546for of the ovarian tissue. Filarid nematode larvae lst and 2nd instars, and a' : O.O42O4,th : were found in the hemocoel and Malpighian tu- 0.12224 for 3rd and 4th instars. Similarly for bules of 2.4ohof the adults. Also, S. spiculatus Rogers'sequation a' : 0.16313,tll: O.O2ll2 was found in the hemocoel of one female and for lst and 2nd instars,and a' : 0.33180,th : conidia were observed in the hemolymph of 4.4o/o 0.52410 for 3rd and 4th instars. Bactimos alone of the adults. No evidenceof tissue damagewas was also testedon Cx. quinquefasciatuslarvaeto observed in ovaries when haplosporidian-like determine the mean percentage of mortality sporesor hyphomyceteconidia were present.Re- among the treatments.First and 2nd instar mor- searchis being conductedto evaluatethe impact tality for the predator alone was70.6o/o,Bactimos ofthese parasitesas natural biocontrol agentsof and predator 94.5o/o,and Bactimos alone 99.2o/o. culicids. For 3rd and 4th instarsmortality was 57.2,91.2, and 66.20/ofor the predator, Bactimos and pred- Bactimos alone, respectively.Holling's Effect of Bactimos on the predatory capacity of ator, and results indicated that predatory action Buenoasp. upon Culex quinquefosciatuslarvre equation increasedas the larval density increased.In gen- (Efecto de Bactimos sobre la capacidad predator Buenoa sp. and depredadorade Buenoa sp. sobre larvas de eral, the action of the Bactimos combined was more effective than the Cu I * qui n quefasc i at us) other 2 treatments. We observed that Cx. quin- M. Reyna, A. Solis, N. Gorrochotegui quefasciatuslarvae were more susceptibleto the and E. A. Rebollar predatory action of Buenoa sp. when Bactimos was present,perhaps Bactimos reduced Laboratorio de Entomologia Medica, because larval strength and therefore antipredatory re- Universidad Autdnoma de Nuevo Le6n, were San Nicolds de los Garza, Mdxico sponses diminished. The synergetic effect ofBactimos (Bacillus thu- Dengue hemorrhagic fever epidemic in ringiensis var. israelensli) was evaluated on the Bucarananga, Colombia, 1992 predatory capacity of Buenoa sp. (Hemiptera: (Epidemia de dengue hernorrigico en Notonectidae) upon Cul ex qui nquefas c i aha. First Bucararnanga, Colombia, 1992) and 2nd larval instars were used for the first test and 3rd and 4th instars in the secondbioassav. J. E. Luna and G. k6n 448 Jouru.rAl or rxr ArasRIcAN Mosqurro Covrnor AssocrerroN Vor. 9. No.4

Table l. Survey and collection results. Before clean-up campaign After clean-up campaign Houses House Houses House Adult Neighborhood inspected index inspected index indext Provenza 40 8 20 93 l3 t4 Fontana l6 4 25 20 J l5 Asturias I 20 6 30 26 4 l5 Diamante II l6 2 l2 70 l0 I Percentageof houses inspected with ad\lt Aedes aegypti.

Table 2. Survey and collection results. Before ULV After ULV Houses House Adult Houses House Adult Neighborhood inspected index indext inspected index indexr Provenza 28 t7 60 28 5 l8 Fontana t7 t2 70 t7 J l8 San Luis 3l l5 48 32 l0 3l Diamante II 33 4 t2 JJ 4 t2 ' Percentageof houses inspected with adrdJitAedes aegypti.

Instituto de Salud, Bucaramanga, Colombia infestations. After the DHF outbreak, an action project with community participation was ini- physicians On March 25, 1992, at the Instituto tiated. The objective was to develop an active de Salud de Bucaramanga reported the first case educational program and get greater community of dengue hemorrhagic fever (DHF) in Bucara- participation. We prepared 3 videos: one with manga city that met World Health Organization puppets for children; another with information (WHO) criteria. The metropolitan areaofthe city "co- for the general public; and an educational video has 800,000 inhabitants, distributed in 14 for orientation of the 500 high school students munas," each with a different number of neigh- who visit houses,conduct surveys,and dissem- borhoods. The first DHF casewas reported from inate educational messagesabout dengue pre- comuna 10. From March 25 until late Novem- vention eachyear. This project received support ber,4l2 DHF caseswere reported from the met- from a grant from the Rotary Foundation through ropolitan area. In May and June, 163 and 140 the Rotary Club from San Juan, PR, to the Bu- DHF caseswere recorded, respectively. During caramanga-ChicamochaClub and the Instituto the outbreak the National Institute of Health in de Salud. Bogoti identified dengue 2 as the infecting se- rotype. Immediately after the first DHF case was re- The impact of substandard piped water supply ported, a larval survey was conducted in the 14 on Aedes acgttpti density in Venezuela comunas of the city. The house index ranged (Deficiencia de agua de acueducto y from 2ohin comuna 12, to 2Og6in comuna 10, densidad lle Aedes ocgypti en Venezuela) to 3306in comuna l. After that survey, a clean- up campaign was conducted and an ultra-low R. Barrera, J. C. Navarro, J. D. Mora, volume (ULV) application of 97o/oMalathion@ D. Dominguez and J. GonzirJez was made and evaluated in the neighborhoods Instituto de Zoologia Tropical, of comuna 10. The evaluation included larval Universidad Central de Venezuela, surveysand landing collection with human bait. Caracas and Ministerio de Sanidad y The results are summarized in Tables I and 2. Asistencio Social, Maracay, Venezuela The ULV application and the clean-up campaign were carried out by health authorities from Previous research showed a link between le- the central government level without community des aegypti infestation indices and a defrciency participation. The results showed that control in piped-water supplies in 2 coastal towns in with poor community participation only pro- Venezuela.Here, we extend the analysis to induced a temporary reduction in Aedes aegypti clude 30 towns along the Venezuelancoast, where DncsMBER1993 Moseurro VBcron Svuposruv 449 we sampled 3,000 housesand identified all con- Honduras, began gathering basic information tainers with and without Ae. aegypti. The hy- about the city and its social and entomological pothesis was that a deficient piped water supply characteristics regarding Aedes aegypti. The city was positively associatedwith the infestation in- of Santa Rita about 25 km away was surveyed dices. Along with the entomological survey, we and used as an untreated area. asked the householdersthe following questions The main objective of this project was to test regardingtheir piped-water supply: sourceofwa- the efficacy of participatory methods with the ter (pipesinside house,pipes only outside house, community and to stimulate and mobilize the none),frequency of intemrptions in water service population to eliminate/control Ae. aegypti (never, seldom, bi-weekly, weekly, daily), and breedingsites, reduce entomological indices (i-e', the length of the intemrptions (hours, days, weeks, the houseindex), and producea sustainableeffort months). in the reduction offactors that enhanceAe- ae- The overall house index was 550/o(range;24- gypti infestations(i.e., inefrcient refusedisposal 850/o),the mean Breteau index was l18 (range: or trash accumulations on patios). 38-263),and the mean container index was24o/o Ten neighborhoods(with house indices from (range: I l-39oh). The order ofbreeding site pos- l2 to 5l) were included in the community pro- itivity was: 208-liter metal drums (40%), house motion program. The neighborhoods were plants (379o),discarded tires (3506),concrete wa- mapped, divided in zones,and taken through a ter tanks (2lVd, cans (149o),miscellaneous con- 4-phase promotion plan to stimulate the for- tainers (l2o/o), and animal drinking pans (8%). mation and continuation of volunteers in Inte- Kruskal-Wallis analysesrevealed significant dif- grated Health Groups (GSI). ferences(P < 0.00 l) among mediansofthe num- During the first 6 months of 1992, the GSI ber of total positive containers (xt : 36.7; n: activity resulted in a 32-92o/odecrease in house 2,996) and positive water-storagecontainers (12 indices, compared with Santa Rita (untreated : 67.O: n : 2,996) with regard to the frequency area),a significant difference(P < 0.05). Besides of intem.rptions. Houses with daily and weekly the reduction in houseindices, the GSI have de- intemrptions had greater numbers of positive veloped other activities in theseneighborhoods, breeding places. The statistical analyses also such as clean-up campaigns,a weekly refusecol- showedsignificant differences(P < 0.00l) among lection system, educational material distribu- the medians of total breeding places(12 -- 42.8; tion, and patio inspections among others, as part n: 2,76O)and water storagebreeding places(x2 of their program. : 114.3:n : 2,760) per house,across the duration ofwater supply intermptions. The number Community participation program for dengue ofbreeding placesper house increasedwith the control in the Magdalena River valleg length interruptions. Most ofthe water-storage of Antioquiq Colombia (790lo),and most ofthe positive water- containers (Participacion comunitaria para el control del storagecontainers were metal drums (88o/o).The dengueen 3 municipios del Valle Medio del data showed that most houseshad piped water Magdalena, Antioquia, Colombia) at some time, so that the main problem with the service of piped water seemsto be its unrelia- G. Alvarez, Y.lipez, Y. Montiel, A. Bolivar, bility (frequent and lenglhy intermptions), which J. Velez and J. P. Escobar caused residents to store water and stimulate le. Semicio Seccional de Salud de Antioquia, production. We acknowledge financial aegypti Medellin. Colombia support for this study from PAHO and CONI- CIT. During 1992, 1,329 denguecases were reported in the Department ofAntioquia. Ofthese,44l (33%) were registeredfrom Puerto Berrio, Yon- Advances in the Aedes acgtpti community-based do, and Puerto Nare, 3 municipalities in the control project in El Progreso, Ilonduras Magdalena River valley where the population is (Advances en el proyecto de control de about 28,000. Dengue 2 virus was isolated by Aedes aegypti con base comunitaria en our laboratory from this area.At the sametime, El Progreso, Honduras) l7 casesof denguehemorrhagic fever (DHF) were E. Fernandez,I. Lagos and C. Sherman confirmed in the Department of Antioquia; 2 were from Puerto Berrio. The 55-gallon metal Proyecto Control Integrado de Dengue, drums usually used for water storage were the Ministerio de Salud de Honduras, most numerous breeding sites for Aedes aegypti El Progeso, Honduras mosquitoes. During the outbreak of DHF, den- In June I 99 l, the Integrated Community-based gue surveillance was increased, a health educa- Aedes aegypli Control Project in El Progreso, tion program emphasizingsource reduction was 450 JounNer on rHe Ar\rsRrclN Mosquro CoNrnor AssocnrroN Vol. 9, No.4

"clean-up" implemented,periodic campaignsand ative for Ae. aegypti larvae. Mosquito surveil- recycling activities were conducted, and ULV lance associatedwith educational messagesand Malathion@ was applied. The objective of this application of sand to the containers is an ex- study was to develop and initiate an action plan cellent strategy for Ae. aegypti control with min- for dengue control with community participa- imal personneland without use of insecticides. tion. To involve the community in the control strategies,residents were invited to assistin several workshops where they learned to minimize The turtle, Pseademysscripta, as a biological their contact with Aedesaegypti. The community control agent for Aedes ocgypti in El Progreso, cooperated in different activities and an action Honduras (La tortuga, Pseudemysscripta, c!,mo group helped design educational materials. En- agente de control biologico de Aedes acgypti en tomological surveys were used to evaluate this El Progreso,Honduras) program. We expect that these strategies will break denguetransmission in the area. If so, we C. Sherman, E. Fern6ndezand H. Portillo will review and evaluate theseinterventions for Proyecto Control Integrado del Dengue, Divisi6n use in other areas. This project has been sup- de Enfermedades Transmitidas por Vectores, ported by a Rotary International Grant through Ministerio de Salud, El Progreso, Honduras the Rotary Clubs from SanJuan, PR, and Medel- part project lin, Colombia, and the ServicioSeccionalde Salud This study was ofa conducted by de Antioquia. the Honduran Ministry of Public Health on the effectivenessof biological control methods for Aedesaegyptl, the principal vector ofdengue fe- Aedesocgypti control without chemicals in ver. Following previous observations of turtle cemeteriesin Puerto Rico (Control de (Pseudemysscripta) predation on Ae. aegypti lar- Aedesaegypti en cernenteriosen Puerto vae, field trials were begun in March 1992 to Rico sin usar insecticidas) study turtle survival, predatory effect on mosquito F. Medina, M. F. Su6rezand G. G. Clark larvae, social acceptability,and turtle presence in treated containers through September Puerto Rico Department of Health, Caguas; 1992. Turtles were introduced into cement cis- Centerfor I nternational Community-based terns ("pilas") usedto store water for household Health Research, Johns Hopkins University, purposesand laundry and into 55-gallon metal Baltimore, MD, USA; and Dengue Branch, drums used for storageof nondrinking water in NCID, CDC, San Juan, PR 3 communities. The predatory activities of tur- procedures Cemeteriesare important foci of Aedesaegypti tles and for basic care of turtles in production and often have many larval breeding these containers were explained to the house- sites.The traditional strategyfor control in these wives. areasin Puerto Rico has been the application of The average survival time of turtles in these temephos in the vases by local environmental containers during the 7-month observation pe- health inspectors.During recent years, the bud- riod was 10-63 days. Of the 79 turtles intro- get for mosquito control programs has been reduced, 73% disappeared;the majority were lost duced and has diminished the availability of in- becausethe householdmembers had insufficient secticidesand operational personnel. information about their management.Only 23% were still present Twenty-six cemeteriesin 7 municipalities in at the end of the observation period and 4o/ohad died. With the high degree Caguas,PR, were monitored from June 1988 to of Jrtly 1992- Each cemetery was visited every 4 acceptability of the turtles by residents,there is a need to achieve more participation months by 2 inspectors. During the visit, the on the part in importance of various containers in producing of the community the distribution and maintenance of turtles in these containers. Ae. aegypti was emphasizedwith the cemetery administrator, including the elimination of water for fresh-cut flowers. All vases flower pots and Laboratory trials of prey selectivity of were inspected and each container with water Macrocyclops albidus anll Mesocyclops was filled with sand. During the last 2 years, the longisetus (Copepoda: Cyclopoidae) number ofcontainers that needed have to sand (Selectividad de presas lle Macrocyclops albidus reapplied was minimal and the level of enthu- y Mesocyclops longisetus en siasm for this control strategy by cemetery au- ensayosde laboratorio) thorities was high. Some cemeteriesnow have a sign at the entrance explaining how to prevent S. M. P6rez-Serna,N. Ornelas-Navas, dengueand promoting the use ofsand. Through H. Quir6z-Martinez, M. H. Badii and July 1992, 25 cemeterieswere completely neg- V. V6squez-Carre6n I

Decelrnrn 1993 Moseurro Vscron SYuposruu 45t

Facultad de Ciencias Biol6gicas, Life tables with nauplii of the same cohort UniversidadAut1noma de Nuevo Le6n, were prepared.Nauplii were introduced individ- San Nicolds de los Garza. M€xico ually in assaytubs witt. Paramecium caudatum as food, a 12 h:12 h light : dark regime, and reg- Although the searching capacities of Macro- ulated temperature, and mortality was recorded cyclops albidus and Mesocyclops longisetus as every 24 h. When copepods reached the adult mosquito predators have been evaluated, their slage,2 pairs were separatedand their progeny preferencesin complex prey systems have not werecounted daily until the last femaledied. The beenanalyzed. The objective ofthis researchwas results were analyzedby life tables,survivorship to evaluate the selectivity or preferenceof2 co- tables, and fecundity tables. pepod speciesin systemswith 2 prey speciesto The survivorship value (l-) was higher in adults obtain important information about their poten- between l0 and 27 daysofage and the fecundity tial as biocontrol agents. value (m.) was higher in copepods 18 and 55 Individual femalesof M. albidus and M. lon- days of age, with 34.7 nauplii per female. The gisetuswere exposedto l, 2, 4, 8, 16, and 32 lst total progeny per female per day (1,'m*) was instar Aedes aegypti or Culex pipiens mosquito higher in l8-day old females (2.1 nauplii). The larvae. The tests were performed in small glass life expectancy(e-) was 34.1 days and the per- containerswith 750 ml of nonchlorinated water, centageof mortality (q-) was greatestin the early with 5 replicates. After 24 h of exposure, the stagesof development. The stable age distribu- number of prey still alive was recorded. tion (C-) was l7oloin time zero at the beginning Resultswere analyzed by Functional Response of the test. The net reproductive rate (\) was models of Holling (1959), Romaya (1971),and 2 1.3 nauplii per generationand the finite rate of Rogers(1972); Ivlev's Index ofElectivity (196l); increase(tr) was 1.2nauplii per day. The intrinsic and Index ofSelectivity (1974\. The best Jacob's rate ofincrease(r-) was 0.15 nauplii. "selectivity" value was the higher value of searchingcapacity and lowest handling time between copepod species. Life expectancyand habitat quality requirements According to Functional Responsemodels, M. for mass production and storageof albidus showed preference for Ae. aegypti, but Mesocyclops longisetus (Expectativa de vida y selectivity and electivity indices were near 0 (no calidad del habitat requerido para la produccion clear preference) and for Cx. pipiens larvae the masiva lle Mesocyclops longisetus) indices were negative (no preference).The sec- A. Valdez, Montemayor, J. Lewis and ond speciesstudied, M. longisetus,had no clear J. M. I. Abdo de la Parra preference in functional response models, although it favored Cx. pipiens, whereaselectivity Facultad de Ciencias Biol6gicas, and selectivity indices were higher toward,Ae. UniversidadAut1noma de Nuevo Le6n, aegypti. San Nicolds de los Garza. Mexico Copepods have been recognized as a potential for gltpt lawae. However, Life tables of Mesocyclops longisetus (Copepoda: control agent Aedesae i little information mass rearing of cope- Cyclopoidae)in the laboratory (Tablas de vida about pods de Mesocyclops longisetus bajo has been reported. A study to better un- production condicionesde laboratorio) derstand the key factors for copepod was conducted in l99l-92 at the Universidad B. Gonzalez-Rodriguez,M. H. Badii, Autonoma de Nuevo [r6n. Parametersstudied H. Quir6z-Martinez and were life expectancy,life history, induced qui- G. A. Rodriguez- Almaraz escence,and use of Parameciun in their diet. Facultad de Ciencias Biol6gicas, Mesocyclops longisetus lived up to 60 days, producing progeny, UniversidadAut6noma de Nuevo Le6n, 74-228 most during the first San Nicolds de los Garza, MExico l0 days ofadulthood. At 2l-28"C, it took l0- 17 days for them to mature to the adult stage. Life tablesprovide a graphic representationof Production of copepodswas density-dependent, population dynamics (survivorship and repro- varying with the number of females. With 25, duction of an organism) and the optimal time to 50, 7 5, and 200 femalesin I gallon of water, an managea population with biological control pro- averageof 1.9, l. 5, 1.0,and 0.3 individualswere grams. In the last 2 years,we have tested cope- produced per day, respectively. pods to control Aedesaegypti. Mesocyclopslon- Paramecium caudatum,an alternative diet for gisetwhas&en evaluated in laboratory and under copepodmass rearing, was cultured in 6 different field conditions but quantitative information food sources:lettuce, beet greens,nonfat pow- about its biology and reproduction is rare. dered milk, wheat, oats, and Maseca@lcorn flour). Jounxar, or rnn Avrnlcen Moseurro Comnol Assocrlrrol Vor. 9, No.4

These diets yielded from 0-1,030 Paramecium/ populations in the lowest and low categories,that ml. The highest production was obtained with is G-5 or 6-10larvae per drum. 18 g lettuce/liter. Greatest production was obtained from day 4 (856 Parameciumlml) to day I 2 (500 Paramecium/ml). Comparative study of susceptibitity and residual and air-borne effect of fenihothion 40 WP After quiescencehad been induced, 80-10006 on Anopheles albimanus in two Nicaraguan villages survival was achieved witlr M. longisetus that (Estudio comparativo sobre la susceptibilidad y had been stored in a moist environment for 6 el efecto residual de fenitrotion 40 WP weeks.To date, this rearing systemhas produced sobre Anopheles albimanus en dos poblados de more than 100,000M. longisetusfor use in local mosquito researchprojects. Nicaragua) P. Rivera, S. Vargas,M. Picado and M. Mercado Field releases of Mesocyclops longisetus (Copepoda:Cyclopoda) for control of Centro Nacional de Higiene y Epidemiologia, Aedes aegypti larvae in 55-gallon Managua, Nicaragua metal drums in Monterrey, M6xico The effect of fenitrothion 40 WP 2 rng/rn2 was (Liberaciones de carnpo de evaluated during l99l in 2localities in 2 differ- Mesocyclops longisetus para el control de ent geographicand climatic regionson the north- Aedes acgypti en tambos met6licos ern and Pacific coastof Nicaragua.Susceptibility de 55-gal en Monterrey, M6xico) as well as bioassaytests were performed. The air- H. Quiroz-Martinez, C. Solis-Rojas and borne effect of residual applications was also M. L. Rodriguez-Tovar evaluated. Results indicate that air-borne fenitrothion 40 WP was effective and controlled Facultqd de Ciencias Bioldgicas, Anophelesalbimanw for up to 60 days after ap- UniversidadAut6noma de Nuevo Le6n, plication. San Nicolds de los Garza. Mexico The biological control of Aedesaegypti is a new Evaluation of the juvenile growth regulator control strategy in Monterrey, Nuevo kon, pyriproxyfen ($3lf83) against three speciesof Mexico. After laboratory evaluation of its pred- mosquitoes in Panama (Evaluacion del regulador atory capacity and becauseofits high searching de crecimiento pyriproxyfen confa capacity, Mes ocyclops longisetus was selectedfor [$311831 tres especiesde mosquitoesen Panama) evaluation under field conditions. We studied the impact of this biological con- E. Adames and J. Rovira trol intervention on the larval Ae. aegypti pop- Universidadde Panama and Ministerio de Salud. ulation in the "Unidad Pedreras" neighborhood Seccionde Entomologia (SNEM), Panama of Monterrey. Three hundred copepods were placed in 60 55-gallon metal drums and 20 55- Ecdysone,ajuvenile and cerebral hormone that gallon metal drums had no copepods.For eval- regulates the cellular functions of growth and uation, samples were taken every l0 days with metamorphosis, has been isolated and chemi- an aQuariumnet, which was moved in a circular cally and functionally characterized (Kopec, pattern 5 times in each drum. Samples were Wigglesworth, Roller, Williams, Fukuda, and placed in small plastic containers to collect and Slama). Subsequently, chemical compounds count mosquito larvae and copepods. analogousto ecdysone(Ecdysoides) and juvenile The resultswere analyzedby linear regression, hormones (Juvenoides),known as insect growth correlation coefrcient, and percent of positivity. regulators(IGRs) or the "third generationof in- When a drum appearedwithout copepodstwice, secticides," were synthesized and evaluated. it was reseededwith 300 copepods.If the drum These compounds are excellent candidates for appearedwithout copepodsa secondtime, it was the control ofarthropods; becausethey act at low excluded from the study. concentrations(e.g., ppb), the evolution ofresis- Ten days after copepod application, 48o/oof tance is slow in comparison with other insecti- the drums were positive but this dropped to 8o/o cides; and they are very safe when used around 12 weeks after treatment, with an overall mean invertebrates,vertebrates, and humans. Several of 2196. The best statistical value was obtained IGRs have been approved by the U.S. Environ- betweencopepod settlement and the larval pop- mental Protection Agency and include: metho- ulation category, which was the lowest through prene, cyromazine, difluomuron, fenoxicarb, and the sampleswith a slope b : -O.44 and a cor- recently pyriproxyfen (5-31183 produced by relation coefficientr : - 0.42.The copepodscould Sumitomo Chemical, Co. Ltd.). have kept Ae. aegypti lst and 2nd instar larval Field and laboratory studies of pyriproxyfen DrcnrnEn 1993 Moseurro Vpcron SYloosruu 453 were conducted againstAedes aegypti, Anopheles days posttreatment).In all cases,the mosquitoes albimanus, and Culex quinquefascialrzsin Pan- were exposed to these concentrations of pyri- ama. Pyriproxyfen (granulated,0. 506 AI) applied proxyfen for 5-6 days. at concentrationsof 0.025 and 0.050 ppm (mgl Similarly, under field conditions, water treated liter), inhibited between 82 and l00o/oof mos- after I day and after 2l days (with 5-l I days of quito emergence,with much mortality during the exposure), tllle 25 ppb concentration produced pupal stageand as the adult attempted to emerge. an EI of 98-1000/oin Ae. aegypti and of l00o/oin Under laboratory conditions, I and 2l days An. albimanus and Cx. quinquefasciatas.The 50 after the water had been treated with concentra- ppb treatment produced 100% EI in Ae. aegypti tions of 25 and 50 ppb, the emergenceinhibition and Cx. quinquefasciatusand 95-99o/oEI in An. (EI) values were l00o/o(25 ppb), l00o/o(50 ppb, albimanus. one day posttreatment),and 87-960lo(50 ppb, 2l