J ou rna l of t he Ame r i c an M o s q u i t o C ont r o l A s s o c i at i o n, 2O(4) :3j 6_399, 2O04The copyright of the publication does not extend to this article.

MOSQUITO VECTOR CONTROL AND BIOLOGY IN LATINAMERICA-A FOURTEENTH SYMPOSIUM

GARY G. CLARK',q.NO HUMBERTO QUIROZ MARTiNEZ (ORGANIZERS)

ABSTRACT, The l4th annual Latin American symposium presented by the American Mosquito ControlAssociation (AMCA) was held as part of the 70th Annual Meeting in Savannah, GA, in February 2004. Theprincipal objective, as for the previous 13 symposia, was to promote participation in the AMCA by vectorcontrol specialists, public health workers, and academicians from Latin America. This publication includessummaries of 37 presentations that were given orally in Spanish or presented as posters by participants from 7countries in Latin America. Topics addressed in the symposium included results from chemical and biologicalcontrol programs and studies; studies of insecticide resistance; and population genetics, molecular, ecological,and behavioral studies of vectors of dengue (Aedes aegypti and Aedes albopictus) and other arboviruses, malaria(Anopheles albimanus and Anopheles pseudopunctipennis), leishmaniasis (Lutzomyia), and Chagas disease (Tri-atoma).

KEY WORDS Mosquitoes, West Nile virus, dengue, malaria, mosquito control, bionomics, Aedes, Anopheles,Culex, C uliseta, Oc hlerotatus, Lutzomyia, Triatoma

INTRODUCTION

The American Mosquito Control Association(AMCA) is dedicated to the study and control ofmosquitoes, other vectors, and other arthropods andpromotes cooperation and interaction among pro-fessionals and students in this field both in the USAand internationally. To promote greater and moreactive participation among and with a portion of itsinternational membership, a Spanish-language sym-posium was held lst at the AMCA Annual Meetingin 1991 and at all subsequent meetings. In additionto providing a forum for scientists whose lst lan-guage is Spanish, the session promoted interactionwith mosquito control industry representatives andinteraction with professional colleagues in the USAwho are involved in mosquito vector control, train-ing, and research at the university level, and withstate and federal government officials.

This publication includes summaries of 37 pre-sentations that were given in Spanish by partici-pants from 7 countries in Latin America. Topicsaddressed in the symposium included results fromchemical and biological control programs and stud-ies; studies of insecticide resistance; and populationgenetics, molecular, ecological, and behavioralstudies of vectors of dengue (Aedes aegypti) andother arboviruses, malaria (Anopheles albimanusand Anopheles pse udopunctipennis), leishmaniasis(Lutzomyia), and Chagas disease (Triatoma). Sum-maries of 11 previous symposia have been pub-lished (Clark and Suarez 1991,1992, 1993; Clark1995, 1996; Clark and Rangel 1997, 1998, 1999;Clark et al. 2000; Clark and Quiroz Martinez20O7,2002).

'Dengue Branch, Centers for Disease Control and Pre-vention, 1324 Calle Cafrada, San Juan, PR 00920-3860.

2 Laboratorio de Entomologia, Facultad Ciencias Biol-6gicas, Universidad Aut6noma de Nuevo Le6n, San Ni-col6s de los Garza, Nuevo Le6n, M6xico.

Financial support for this session was providedby the following sponsors: Syngenta, Valent, Well-mark, and the Pan American Health Organization.Funds from these sponsors provided Annual Meet-ing registration and partially defrayed travel ex-penses for many symposium participants. Enthusi-asm and interest for this symposium amongSpanish- and non-Spanish-speaking participantswas high and it will continue to be part of futuremeetings.

SUMMARIES

Epidemiology of West Nile virus in northernMexico in 2003

Armando Elizondo-Quiroga, Ildefonso Fern6ndez-Salas, Juan Francisco-Contreras, J. I. Gonz1lez,Darwin Elizondo-Quiroga, Guadalupe Reyes-Solfs,

Brad Blitvich, and Barry J. Beaty

Laboratorio Entomologia Medica FDC-UANL,Monterrey, Mexico; and Arthropod-borne Infec-tious Disease Laboratory, Colorado State Univer-

sity, Fort Collins, CO

West Nile (WNV) began to disperse in Mexicoin 2003. Here, we report findings of an avian andequine surveillance program conducted in north-eastern Mexico. Bird collections from October2OO2 to October 2003 totaled 737 individuals. Thelst occurrence of WNV-seropositive birds wasmade in February 2OO3 in the northern part of thestate of Nuevo Leon. Two migratory species (Zoon-otrichia leucophrys and Spizella pallida) and I res-ident species (Passer domesticus) tested positive tol1l2c WNV monoclonal antibodies by blockingenzyme-linked immunosorbent assay. In March inTamaulipas State, 3 sampling areas (El Carrizal, inthe city of Matamoros located near Brownsville,TX; San Fernando; and La Pesca) yielded seropos-

376

DeceN.{sen 2004 Moseurro Vecron CoNrnoL lNo Brolocy rN LATIN Avnnlca-A FounrseNrn Svrraposruru 377

itive birds. West Nile virus-positive bird sera alsowere collected in La Escondida in Coahuila Statein May. Again in mid-summer, we found seropos-itive birds in the suburbs of the city of Monterrey(population 4 million). Overall, of 737 birds col-lected in the 3 states of northeastern Mexico, 20(2.7Vo) were seropositive, whereas 6 (54.5Vo) ortt ofI 1 localities yielded seropositive birds. Reportsfrom the Nuevo Leon State Health Departmentyielded only 1 seropositive human case in August2003. Reports of dead and sick WNV-infected hors-es increased in spring and summer of 2003 in Nue-vo Leon State.

Detection of dengue viruses in field-caughtAedes aegyprr- (Diptera: Culicidae) in Maracay,

Aragua State, Venezuela, by type-specificpolymerase chain reaction

Ludmel Urdaneta, Martha Pernalete, NormigZoghbi, Yasmin Rubio-Palis, Roybel Barrios, Jos6

Rivero, Guillermo Comach, Maria Salcedo, andFlor Herrera

Secci4n de Biologia Molecular del Cento de In-ve sti gacione s B iomddicas ( B IOM ED ),

Maracay, Venezuela

In a prospective field study conducted from No-vember 2000 to December 2001, adult female Ae-des aegypti were caught from several municipalitieswith high dengue (DEN) transmission in Maracay,Aragua State, Venezuela, and were tested for den-gue viruses (DEN-I, DEN-2, DEN-3, and DEN-4).Virus detection was carried out by using reversetranscription polymerase chain reaction (RT-PCR).We analyzed a total of 296 pools of Ae. aegypti (n: I,632 mosquitoes). From these, 154 pools (n :

469 mosquitoes) were collected from houses inwhich there were dengue-infected residents ("den-gue case") and 142 pools (n : 1,163 mosquitoes)were from the houses surrounding the dengue case("neighbor"). From the dengue case group, 8 mos-quito pools (5.2Vo) were positive for dengue virus-es, including DEN-I (O.\Eo), DEN-3 (3.2Vo), andDEN-4 (l.2%o). From the neighbor group, 18 mos-quito pools (12.7 7o) were positive for dengue vi-ruses, including DEN-3 (Il.97o) and DEN-4(O.8Vo). From these 26 RT-PCR-positive mosquitopools (containing 1-25 mosquitoes each), 22 pools(84Vo) were positive for DEN-3 virus. The mostprevalent serotype in the 2001 dengue outbreakalso was DEN-3. Virological surveillance of den-gue viruses in natural populations of Ae. aegyptibyRT-PCR could provide a powerful tool to assist inthe control of dengue in this hyperendemic regionin Venezuela.

Climate variability and dengue in ahyperendemic area of northern Venezuela

Yasmin Rubio-Palis, Ludmel Urdaneta, Jos6 Parra,Hern6n Guzm6n, Vfctor S6nchez, and

Flor Herrera

BIOMED, Universidad de Carabobo, Maracay, Ar'agua, Venezuela; Salud Ambiental y ContralorfaSanitaria, MSDS, Maracay, Aragua, Venezuela;CORPOSALUD, Maracay, Aragua, Venezuela; andInstituto de Altos Estudios "Dr. Arnoldo Gabal-

don," MSDS, Maracay, Aragua, Vene<uela

Dengue is a major public health problem in Ve-nentela. The situation has worsened in recent years(e.g., in 2OOl, a total of 83,180 cases of classicdengue, 6,541 of dengue hemorrhagic fever [DHF],and 5 deaths were reported). To establish the pop-ulation pattern of Aedes aegypti in relation to rain-fall, a longitudinal study was conducted betweenJanuary and December 2001 in the metropolitanarea of Maracay, Aragua State. Adult mosquitoeswere collected monthly inside houses by using abackpack aspirator. Climatological data (rainfall)were obtained from the Venezuelan Air Force Basein Maracay. A total of 845 houses in 87 barrioswere visited, and 8O.4Vo (679) of the houses werepositive for Ae. aegypti. Vector abundance variedfrom 3.6 Aedeslhotse during April (at the end ofdry season) to 14.7 Aedeslhouse during August (thepeak of rainy season). Positive significant correla-tions were found between monthly rainfall and thenumber of Aedes per house (P : 0.01), the numberofclassic dengue cases (P : 0.006) and the numberof DHF cases (P : 0.02), as well as the number ofdengue cases (classic and DHF) and abundance ofAe. aegypti (P : 0.0001). Examination of the re-sults of the Spearman correlation analysis suggest-ed that rainfall positively influenced the abundanceof Ae. aegyptl, which resulted in an increase of thenumber of cases of dengue and DHF Rainfall maybe used as an indicator to apply effective and effl-cient vector control measures in Maracav.

A survey of anopheline species andl Plasmodiuminfectivity in the Peruvian Amazon

Carmen Flores and Jeff Stancil

U.S. Navy Medical Research Unit, Lima, Peru

ln 2OOl-02, 100 localities in the departments ofLoreto, Ucayali, San Martin, and Madre de Dios,Peru, were surveyed for anophelines utilizing hu-man-baited collections. A total of 86,267 anophe-lines were collected from 89 localities, includingAnopheles benarrochi, An. darlingi, An. mattogros-sensis, An. triannulatus s.1., An. rangeli, An. os-waldoi s.1., An. nuneztovari, An. forattinii, An. in-termedius, An. sp. near fluminensis, An. peryassui,

378 Jounxel oF THE AMERTCIN Mosquno CoNrnol AssoctenoN VoL. 20, No. 4

An. nimbus, and An. deaneorum. Of these. 84.654(8,815 pools) were tested by enzyme-linked im-munosorbent assay for the presence of Plasmodiumcircumsporozoite (CS) proteins, but only 2 species,An. benarrochi and An. darlingi, were found to bepositive. In An. darlingi, P. falciparum CS proteinswere found in O.1Vo of the 1,422 pools and P. vivax210 CS proteins were found in O.28Vo of the pools.Of the 6,323 An. benanochi pools, 0.087o werepositive for P. falciparum CS proteins, O.O32Vowere positive fot P. vivax 247, O.Ol6Vo were posi-tive for P. vivax 210/247, and O.Ol6Vo were positivefor mixed P. falciparum and P.vivax 247 CS pro-teins.

Effect of tempertature on the developmentalcycle, life expectancy, and survivorship ofAnopheles albimanus (Diptera: Culicidae)

related to an El Nifto event

Guillermo L. Rfa, Martha L. Quifr6nes, Iv6n D.Velez, William Rojas, Germ6n Poveda, Juan S.

Zuluaga, and Daniel Ruiz

Programa de Estudio y Control de EnfermedadesTropicales (PECET), Universidad de Antioquia,Medellin, Colombia; Corporaci6n para Investiga-ciones Biol6gicas, Medellin, Colombia; and Escue-la de Geociencias y Medio Ambiente, Universidad

Nacional de Colombia. Medellin. Colombia

In Colombia, a strong association has been ob-served between malaria incidence and temperatureduring El Niflo events. Climatic changes might alterthe vector population dynamics and therefore in-crease malaria transmission. To evaluate the influ-ence of temperature on development cycle, life ex-pectancy, and survivorstip of Anopheles albimanus,the following study was performed under controlledlaboratory conditions. The study was conducted at 4different temperatures (i.e., 24, 27, 30, and 33"C).For each selected temperature, the development cy-cle, life expectancy, and survivorship were evaluatedin 4 cohorts of 100 1st instars each. Examination ofresults showed that increased temperatures reducedthe development cycle, but no significant differenceswere observed at the 2 higher temperatures. Similarresults were obtained for survivorship. Life expec-tancy was reduced when mosquitoes were incubatedat 33"C, in contrast to mosquitoes incubated below30"C, where no significant differences were ob-served. Taking these results all together, we hypoth-esize that during El Niflo events, increased temper-atures produce a reduction in the larval developmentwithout affecting the life expectancy. This allows thevectors to live longer in the adult stage, thereforeenhancing the probability of more infective bites andthus increased malaria transmission.

Seasonal study of containers with Aedes aegypti(L.) in Nuevo Leon during 2OO0-02

Juan Francisco Martinez Perales

Laboratorio Entomologia Medica FDC-UANL,Monterrey, Mexico

Breeding sites of Aedes aegypti were analyzedfrom 2000 to 2OO2 in the metropolitan area of Mon-terrey. Containers were classified as "controllable,""destructible," and "controllable with temephos"in order to determine the most permanent breedingsites (deposits) present. During 2000, the percent-age of positive containers was 2.6Vo. When this val-ue was considered as IOOVo and analyzed, 23.37oof the containers were controllable, 25.37o werc de-structible, and 57.3Vo were controllable with teme-phos. In 2001, the percentage ofpositive containerswas 2.5Vo. Of this total, 25.6Vo were controllable,21.67o were destructible, and 5l.4%o were control-lable with temephos. In 2OO2, the percentage ofpositive containers was 2.7Vo. These data include25Vo controllable,23To destructible, and 52Vo con-trollable with temephos. The most common positivecontainers during the 3 years of study were thosewhere larvicide was used.

Comparison of Aedes aegypti density indiceswith the currently used larval indices

Claudia M. E. Romero-Vivas andAndrew K. I. Falconar

Grupo de Investigaciones en EnfermedadesTropicales, Departamento de Ciencias Bdsicas

Mddicas, Fundaci6n Universidad del Norte,Bananquilla, Colombia

The aim of this study was to compare densityindices of Aedes aegypti obtained in a dengue fever(DF) endemic area where the most abundant andproductive vector breeding sites were located in-doors. One hundred twenty premises in an urbanarea of Colombia where DEN-I and DEN-2 virusescocirculated were randomly selected and sampledfor 7 months. The geometric mean monthly num-bers (density index [DI]) of eggs of Ae. aegypti(ODI), 4th-stage larvae (LDI), pupae (PDI), andadults (ADI) were calculated based on the use ofovitraps, nets, and manual aspirators, respectively.A negative temporal correlation was observed be-tween the LDI and the ODI (r = -0.83, df : 5, P< 0.01). Positive temporal correlations were onlyobserved between the LDI and the PDI (r : 0.9O,df: 5. P < 00.5) and the Breteau and house in-dices (r : 0.86, df : 5, P < 0.01). No other cor-relations were found between these indices and anyof the other density indices or the incidence of sus-pected DF cases in residents, the temperature, therainfall, or seasonal fluctuations. Therefore, our re-

Decevsen 2004 Moseuno Vecron Coxrnol AND BIoLocy nq L.a.rrN AvBntcr-A FounrepNttl Svrrlpostulr 379

sults probably were due to the most productrvebreeding sites of Ae. aegypti (large water contain-ers) being located indoors in this study area.

Using ecological niche modeling inentomological supervision of Aedes aegypti

in Mexico

Carmen Martinez Campos, Yoshinori Nakazawa,Enrique Martfnez-Meyer, and

A. Townsend Peterson

Laboratorio de Entomologia, Instituto de Diagn6s-tico y Referencia Epidemiol6gicos (InDRE), Secre-tarfa de Salud, DF, Mexico; Instituto de Biologta,Universidad Nacional Aut6noma de Mdxico (IBUN-AM), DF, Mexico; and Natural History Museum,

University of Kansas, Lawrence, KS

Epidemiological surveillance systems for emerg-ing infectious diseases involve monitoring of bothhumans and vectors. Vector sampling is importantfor determining spatiotemporal dynamics of theirpopulations, with the goal of designing preventionand control strategies or emergency responses. Tia-ditional entomological surveillance programs forAedes aegyptl in relation to dengue and denguehemorrhagic fever include mosquito and larvalsampling in both domestic and peridomestic envi-ronments. Ttris information nevertheless generallylacks wide geographic and temporal coverage,which limits the ability to efficiently respond to po-tential outbreaks. New approaches for modelingdistributions of species based on their ecologicalniches have proven powerful and effective in pre-dicting species' geographic distributions, even withrelatively sparse and scattered occurrence data. Weevaluated the use ofoccurrence datafor Ae. aegyptiobtained from traditional sampling methods, cou-pled with satellite imagery and additional environ-mental data, to produce time-specific distributionalmodels for this species by using ecological nichemodeling to identify areas of potential risk of in-fection of diseases transmitted by this vector inMexico.

Preliminary evaluation of pupal collectingmethods in drums in Maracay, Venezuela

Milena B. Mazzarri and Marco F Suarez

Ministerio de Salud y Desarrollo Social, Maracay,Venezuela; and CPC PAHO0VHO, Barbados

Sampling of aquatic stages of Aedes aegypti trasmade valuable contributions to the development ofvector control methods. Mosquito surveillance hasgreatly improved and there is a permanent concernthat it is necessary to evaluate the productivity ofall containers. Moreover, the pupal survey is an im-

portant tool that helps evaluate containers, reveal-ing important information about the specific riskcontainer as a function of vector abundance. Tomeasure the productivity of containers, samplingmethods for pupal collections were carried out inthe laboratory by using 200-liter drums. Threestrategies for collecting pupae (A, C, and H), eachwith 3 replicates for each method on 5 differentdays were tested. Between 100 and 400 immaturestages were released into full water drums. Signif-icant differences between methods were found (P

< 0.001; Duncan's multiple test). Additionally, thepercent recovery for immature stages for each sam-ple method was determined as 93Va for strategy"Abel" (A),56Vo for "colador" (C), and TlVo for"hamaca" (H). The mean of percent recoveryshowed significant differences among methods Aand H compared with C (P < 0.05). The numberof immersions were counted in I min, with themean of A : 1, of C : 6, and of H : 4. In viewof these results, a survey method involving thecounting of pupae in a field test is needed to eval-uate containers as useful tools for planning vectorcontrol programs.

Estimation of gonotrophic cycle length, survivalrate, and host-seeking behavior of Aedes

albopictus in southern Mexico

M. Casas, A. Ulloa, and M. E Ortiz

INSP/Centro de Investigaci6n de Paludismo, Insti-tuto Nacional de Salud Priblica, Tapachula,

Chiapas, Mexico

Recently, Aedes albopicras (Skuse) was reportedfrom Chiapas, Mexico. The rapid expansion of thenatural range of Ae. albopictus, along with popu-lation growth, has caused concern because of itspotential as an arbovirus vector. Little informationis available concerning the reproductive biologyand behavior of this species in this region. Here,we present an evaluation of a time-series techniqueto estimate the length of the gonotrophic cycle andsurvival of host-seeking populations of Ae. albop-ictus collected in southern Mexico. Diel collectionswere carried out by using human bait over a 2l-day period in a cemetery located along the perim-eter of Thpachula, Chiapas. The gonotrophic cyclewas estimated to be 4 d and the daily survival ratewas estimated vertically to be 0.96 (daily parity rate: 0.85 for a 4-day gonotrophic cycle of 0.961/4),according to Davidson's equation. Further, we de-termined that the host-seeking activity was bimod-al, with the lst peak between 0800 and 1000 h anda 2nd peak between 1400 and 1600 h.

380 Jounrvll op rHE AlranntceN Mosquno CoNrnol AssoctetoN VoL. 20, No. 4

fntegrated control of Aedes aegypti andl Ae.albopictus: a progress report

Juan I. Arredondo-Jim€nez, Norma E. Rivero, andJos6 Ord6ffez-GonzLlez

Centro de Investigaci6n de Paludismo, InstitutoNacional de Salud Prtblica, Tapachula,

Chiapas, Mexico

Current dengue vector control efforts fail to sup-press mosquito populations and cannot prevent den-gue transmission. The causes for this situation in-clude limited resources, defective logistics, poortraining of operational personnel, null communityparticipation, and favorable ecological conditionsthat promote abundant mosquito populations andcirculation of dengue viruses. This ongoing studyaimed to develop and evaluate dengue vector inte-grated control strategies compared to current ap-proaches in several small to mid-sized cities insouthern Chiapas, Mexico. Tieatments were anti-larval measures with no insecticide, including com-munity education and participation (CP) + com-plete adulticide measures, including indoor "fast"

residual spraying with alpha-cypermethrin (Fen-dona@) (FS) of dengue-positive and high-risk hous-es and space treatments with d-phenothrin (Anvil@)(ST); antilarval measures with insecticide (ALI),with CP and temephos (Abate@) pellets (TP) + ST;ALI + FS + ST; and the conventional approach tocontrol, including larviciding with granular teme-phos, elimination of disposable containers, and STwith permethrin (Aqua Reslin@ Super). The out-come of these interventions was evaluated by en-tomological assessments and passive dengue sur-veillance. After 6 months, integrated measuresproved to be effective in reducing 85-987o of mos-quito indicators, whereas no apparent suppressionwas observed where conventional measures (with-out ST) were undertaken. Community participationreduced larval indicators where no temephos wasdistributed.

Influence of the blood-meal source on thedevelopment of Triatoma phyllosoma

(Hemiptera: Reduviidae)

J. A. Martinez-lbara, A. Lucia-Romero, J. C.Trujillo Garcia, and B. Nogueda-Torres

Area de Entomologia Mddica, Centro (Jniversitario

del Sur, Universidad de Guadalajara: LaboratorioEstatal de Salud Prtblica, Servicios de Salud en elEstado de Oaxaca; and Escuela Nacional de Cien-cias Biol6gicas, Instituto Politdcnico Nacional,

Mexico City, Mexico

Triatoma phyllosoma is among the most impor-tant vectors of Trypanosoma cruzi, the causativeagent of Chagas disease, in Mexico because of its

occurrence in houses and high T. cruzi infectionrates in villages of the Pacific Coast of Mexico. Aswith some other Triatominae species, T. phyllosomausually feeds on mammals or birds, depending onthe availability of these hosts. Most studies on Tri-atoma species (e.g., T. infestans, T. brasiliensis, T.sordida, and T. pseudomaculata) have shown thatspecimens fed on mammals (mice) have shorter de-velopmental times and lower mortality rates thanthose fed on birds (pigeons). Thking into accountprevious information on the host preference of T.phyllosoma, the objective of this study was to de-termine the influence of the blood-meal source onthe life cycle, feeding, and defecation patterns of Z.phyllosoma. Specimens were separated in 2 groupsof 150 lst instars, placed in plastic glasses (10 oneach), fed weekly on New Zealand rabbits or leg-horn hens, and checked daily to record molting andmortality. No significant (P > 0.05) differenceswere recorded in the life cycle among the speci-mens fed on hens (mean 192.6 'r 22.7 days) andthose fed on rabbits (2O5.7 -r 34.8 days). Also, nosignificant (P > 0.05) differences were recordedamong the specimens fed on hens and those fed onrabbits related to time for getting a complete bloodmeal, defecation pattems in most stages, and per-cent mortality of each stage. Our results showedthat the nutritional characteristics of blood fromhens were similar to those of blood from rabbitsand different from those found in previous studiesof unrelated species, but similar to results fromstudies on 2 closely related species, T. longipennisand T. picturata. Therefore, these results supportthe idea of an important association of Z. phyllo-soma with domestic birds, as cited in previous ar-ticles for related species.

Species diversity and biting behavior of sand-fly fauna in two foci of leishmanisis in Mexico

E. A. Rebollar-T€llez, E. Tun-Ku, P. Manrique-Saide, and F J. Andrade-Narvez

Centro de Investigaciones Regionales "Dr. HideyoNoguchi"; and Facultad de Medicina Veterinariay Zootecnia, Universidad Aut6noma de Yucatdn,

Mdrida, Yucatdn, Mexico

Leishmania mexicana is the protozoan causingcutaneous leishmaniasis in southern Mexico. Pre-vious studies have reported 2 suspected vectors,Lutzomyia olmeca olmeca and L. cruciata. As partof the epidemiology of disease in Campeche, Mex-ico, we conducted an entomological survey in 2allopatric foci in Campeche. We sought to docu-ment the fauna and biting habits of sand-fly speciesin the villages of Dos Naciones and La Guadalupe,Campeche, Mexico, during 1 transmission cycle.We found that both diversity and species richnesswere similar in Dos Naciones and La Guadalupe.However, when comparing Simpson's dominance

DECEMBER 2004 MoseutTo VEcToR CoNrRoL ANp BIoLocY IN LATIN AMERTCA-A FoUR'I-EEN1'H SYMPOSTM 381

index, it was observed that La Guadalupe had a

higher index than Dos Naciones. When comparingthe biting rhythms of sand flies caught in Shannontraps, it was found that regardless of the location,sand flies were more active after dusk from 1800to 2000 h. Lutzomyia olmeca olmeca was the onlyspecies caught in rodent-baited traps. Out of 16species collected in both sites, transmission of theparasite appears to be restricted mainly to L. olmecaolmeca and secondly to L. cruciata. A brief dis-cussion of the impact of deforestation on the sand-fly fauna is presented in special reference to thesuspected vectors.

A description of phlebotomine sand flies fromthe Peruvian Amazon

Roberto Fernandez and Jeff Stancil

Instituto de Investigacion de Enfermedades Tropi-cales de la Marina de los Estados Unidos,

Lima. Perrt

Phlebotomine sand flies were collected from theIquitos region of the Peruvian Amazon. Collectionswere made by utilizing Cor-baited light traps sus-pended at different heights from the forest floorthrough the canopy (0, 1.5, and 8-10 m). A totalof 443 sand flies were collected (35Vo males and65Vo females). Eleven subgenera and 34 specieswere identified, including those in the genera Psy-chodopygus, Nyssomyia and Trichophoromyia,which represented the majority of the collections(22, 24, and 257o, respectively). The greatest di-yersity of species was found in the Psychodopygus(8), Nyssonyia (6), and Aragoi (4) groups. Speciesdomposition often varied based on the collectionheight, and included Lutzomyia saltuosa arrd Lut-lomyia sp. I del Napo (sp. nov.) in the ground-levelcollections; L. davisi artd L. hirsuta were most com-monly collected at 1.5 m, as was the new speciesLutzomyia sp. 2 del Napo; and L. antunesi, L. yuilli,and L. umbratilis were the predominant species inthe collections from 8 to l0 m.

Genetic variability among populations ofOchlerotatus taeniorhynchzs (Diptera:

Culicidae) from Colombia

Bello Felio, Ferndndez Jos6, Escobar Jesris,Ci4rdenas Estrella, Ruiz-Garcia Manuel

Laboratorio de Entomologfa, Departamento deCiencias Bdsicas, Universidad de La Salle, BogottiDC, Colombia; and Laboratorio de Biologfa Evo-lutiva y Molecular, Departamento de Biologia,

P ontific ia Univ e rs idad J av e riana,Bogotti DC, Colombia

Ochlerotatus taeniorhynchzs (Wiedemann) is azoophilic species and a vector of Venezuelan

equine encephalitis virus in Colombia and Vene-

zuela. Its geographical distribution along the Atlan-

tic and the Pacific coasts ranges from Massachu-setts (USA) to Santa Catalina (Brazil) and fromCalifornia to Peru, respectively. In Colombia, it isfound in forests and inside houses along bothcoasts. Genetic diversity was compared amongmangrove-forest populations of Oc. taenio rhync husfrom 7 locations along the Atlantic coast in Colom-bia (San Bernardo del Viento, Coveflas, Cartagena,Barranquilla, Cienaga, Dibulla, and Riohacha) byexamining genetic variation at 10 isoenzyme loci.The mean heterozygosity ranged from 32 to 457o,with 3.4 alleles detected per locus, and the per-

centage of polymorphic loci was 7O%o. Nei's ge-netic distances among populations ranged from0.011 to 0.119. The estimated number of migrants(3.36) based on Wright's F statistic indicated lowlevels of gene flow among mangrove-forest popu-lations of Oc. taeniorhynchzs from the Atlanticcoast from Colombia.

Genetic consequences of events on Anophelesaquasalis island populations

Yadira Raneel

LBV, IZT-UCV, Caracas, Venezuela; and Depart-ment of Systemntic Biology, Smithsonian Institu-

tion, Washington, DC

Islands offer an ideal model to examine the con-sequences of historical and demographic events onevolutionary processes related to genetic variabili-ty. In mosquitoes, the degree of genetic differenti-ation is important for reconstructing phylogeo-graphic histories and for clarifying features ofpopulation biology. Barbados, a young (700,000BP) oceanic island, is set off from the Lesser An-tilles chain. It was presumably colonized by mos-quitoes via natural older invasions from the mucholder volcanic islands in the main Lesser Antilleanarc, through recent human movement, or both.Anopheles aquasalis from the eastern coast of theVenezuelan mainland was used as representative ofa large outbreeding continental population. Popu-lation samples were analyzed for genetic variabilityat 16 enzymatic loci. The degree of genetic differ-entiation was assessed between populations with re-spect to within-population indices of genetic diver-sity and Wright's F statistics. Analysis revealeddifferences in the average number of alleles per lo-cus, heterozygosity, the proportion of polymorphicloci, and allele frequency distribution. However, theflxation index demonstrated little genetic structurebetween populations from Barbados and Venezuela.A tentative hypothesis for explaining these resultsis that the Barbadian population arose from bottle-necks of Venezuelan populations in steps throughthe Lesser Antilles.

382 JounNer or rus AvsnrceN Mosqurro CoNrnol AssocrATroN Vor-. 20, No. 4

Population genetics of Aedes aegypti inOaxaca. Mexico

M. L. Mufloz, F Mercado-Curiel, A. Diaz-Badillo,J. Pascual, K. E. Olson, B. Beaty, and

W. C. Black IV

Department of Genetics and Molecular Biology,CINVESTAV-IPN, Mexico DF, Mexico: and Colo-

rado State University, Fort Collins, CO

Aedes aegypti is the primary urban vector of den-gue and yellow fever viruses. Dengue fever anddengue hemorrhagic fever are public health prob-lems in the tropics and subtropics, and are exacer-bated by urbanization, population movement, andlifestyles that increase the man-made larval habitatsof the mosquito vector. By using random amplifledpolymorphic DNA markers, we have shown thatcollections of Ae. aegypti from the southern PacificCoast of Mdxico had as much genetic variationamong collections 60 km apart as among all col-lections, and that mosquitoes from northeasternM6xico were genetically isolated by distance andgenetically homogeneous within a range of 9O-25Okm. We showed by variation in mitochondrial de-hydrogenase subunit 4 gene (ND4) haplotypes thatnortheastern collections were genetically differen-tiated and had lower genetic diversity than Yucatanand western Pacific coastal collections. Because ofthe importance of this vector and the high frequen-cy of dengue in Oaxaca, M6xico, the aim of thisstudy was to determine the genetic structure andvector competence of Ae. aegypti. We analyzed 1o-cal patterns of gene flow in Ae. aegypti over a totaldistance of 300 km and among 4 populations in acity within a distance of 8 km. Genetic variation inND4 haplotypes was examined in 60 mosquitoesper collection. Ten new haplotypes were detectedand we are currently studying the vector compe-tence of these populations. This research was sup-ported by National Institutes of Health grant G-4632-1.

Mitochondrial DNA variation arnong Aedesaegypti populations in Venezuela

Flor Herrera, Ludmel Urdaneta, Jos6 Rivero,Normig Zoghbi, Pernalete Martha, Yasmin Rubio-

Palis, Elina Rojas, and Omar Cornejo

BIOMED, Facultad de Ciencias de la Salud, Univ-ersidad de Carabobo, Nrtcleo, Aragua, Venezuela;Salud Ambiental y Contralorla Sanitaria, MSDS,Maracay, Aragua, Venezuela; Centro de Investi-gaciones "J. W. Torrealba"-UlA, Trujillo, Vene-zuela; and Instituto Venezolano de Investigaciones

Cient{ficas, Miranda, Vene zue la

We examined the distribution of mitochondrialDNA haplotypes among populations of Aedes ae-

gypti to test for genetic diversity by using an in-dependent genetic marker. A 387-base-pair regionof the reduced nicotinamide adenine dinucleotidedehydrogenase subunit 4 from the mitochondrialDNA (mtDNA) was amplified by the polymerasechain reaction (PCR) in 1,000 mosquitoes collectedfrom 20 locations in different states of Venezuela.The PCR products were tested for variation by us-ing single-strand conformation polymorphism anal-ysis, and 8 haplotypes were detected. Examinationof the results indicated that populations are not iso-lated by distance and that free gene flow occursamong the sites where these collections were made.However, it is clear that mosquitoes in the collec-tion from Maracay (a city in Aragua State) are ge-netically distinct in mtDNA haplotype frequenciesfrom mosquitoes in all other collections. Becausethe Maracay Health Service has implemented astrong insecticide-based vector control programduring the last 6 years, this may provide conditionsfor selection of some haplotypes. It will be inter-esting to determine if these haplotypes are associ-ated with insecticide resistant markers.

Effects of sublethal doses of temephos on aCuban strain of Aedes aegypti

Silvia Sur{rez, Domingo Montada, Mayda Castex,Agustin Navarro. and Maureen Leyva

Instituto de Medicina Tropical "Pedro Kouri,"La Habana, Cuba

Temephos has been used in Cuba continuouslysince 1981 to control larvae of Aedes aegypti. Thisinsecticide has been applied in containers for do-mestic use at I ppm,/liter. This dosage may be af-fected when cleaning the containers and because ofoperational mistakes. Sublethal concentrations oftemephos (3OVo lethal concentration [LC3o], LC50,and LCro) were calculated using Probit-log analysisand were applied during 24 h to 4th instars of astrain of Ae. aegypti from Havana City, Cuba.Twenty-five adults of each sex of those thatemerged from the treated larvae, as well as con-trols, were reared in 30 X 30 X 30-cm boxes in thelaboratory and fed a lOVo sugar solution and guineapig blood. A container with water was placed in thecage for mosquito oviposition. This experiment wasreplicated 5 times. The applied concentrations(0.01089 mg/liter [LC.o], 0.01386 mg4iter [LCro],and 0.01764 mglliter [LCro]) increased female lon-gevity. Both the treated and control females had 5gonotrophic cycles, although the treated onesshowed statistically significant less fecundity andegg fertility than the controls. The treated mosqui-toes showed less population growth than the con-trols, as expressed by the finite rate of increase andintrinsic rate of natural increase.

DECEMBER 2004 Moseurro VEcroR CoNTRoL ANp BroLoGy IN LATIN AMERTCA-A FoURTEENTH SYMPoSIUM 383

Larval resistance of three populations of Aedesaegypti to temephos in Trujillo State, Venezuela

Leslie Alvarez, Arelis Briceflo, Elina Rojas, andJ. V. Scorza

(lniversidad de los Andes, Nrtcko Rafael Rangel,Trujillo, Venezuela

The insecticide resistance problem, along withthe absence of a domestic hygiene program in Tru-jillo State, Venezuela, have contributed to the highprevalence of dengue. The most widely used or-ganophosphate insecticides are temephos as a lar-vicide and fenitrothion and malathion as adulticidesfor control of Aedes aegypti. The objective of thisstudy was to determine the level of resistance of 3populations of Ae. aegypri from the localities Ha-tico (HT), Tres Esquinas (TE), and Paramito (PT)in the state of Trujillo to temephos. Fourth-stagelarvae were assayed by using World Health Orga-nization methodology. Resistance to temephos wasfound in all strains when compared with the sus-ceptible Rockefeller strain. Ratios of resistancewere estimated as 9.1 (HT), 9.6 (TE), and 13.3 (PT)for the median lethal concentraton (LC.o) and 13.9,12.7, and 12.7 for the LCr' respectively. Exami-nation of the results indicates that insecticide resis-tance in Ae. aegypti is a serious problem of a focalnature that should be treated independently.

Laboratory and field evaluation ofMacrocyclops albidus for control of larval

Aedes aegypli in Cuba

Zulema Menendez, Silvia Suarez, Israel GarciaAvila, Manuel Diaz, Ren6 Gato, and

Israel Garcia Garcia

SOCZOO, La Habana, Cuba

Predatory capacities of Macrocyclops albidus onlarvae of Aedes aegypti in different containers wereevaluated. Copepods were collected in 3 Cubanprovinces and cultured under laboratory conditionsat 26 + 2"C ard a l2:I2 h light:dark cycle. Petridishes and plastic 7-liter containers in the labora-tory and 200-liter drums in field trials were usedfor predation experiments. A single adult femalecyclopoid, previously held for 24 h without food,was placed in each petri dish with 50 newlyhatched larval Ae. aegypti. Surviving larvae werecounted after 24 h. Plastic 7-liter containers with 5Iiters of dechlorinated water and 3 g of leaf litterwere used to test 3 combinations of predatory den-sities: 25, 50, and IOO Ma. albidus and 300 larvalAe. aegypti. Field trials were conducted in drumswith 200 I of dechlorinated water and 5 g of leaflitter for 2 combinations of predatory densities: 100and 200 Ma. albidus, each with 300 larval Ae. ae-gypti. All experiments were replicated 5 times and

separate controls with no copepods were studied in

similar containers. Surviving larvae and remainingcopepods were counted after 6 days. Analyses of

variance showed a significant reduction of larvae in

all the treatments with copepods.

Predatory capacity of Piona amimitli on larvalCulex restuans

Carlos Humberto Marin Herr'indez, CristinaCramer Hemkes, Humberto Quiroz Martfnez,

Violeta Ariadna Rodriguez Castro, andAnita Hoffmann

Laboratorio de Acarologia; Facultad de Ciencias,Universidad Nacional Aut6noma de Mdxico; andLaboratorio de Entomologia, Facultad de Ciencias

BioI6 gicas, U niversidad Aut6noma deNuevo Le6n, Mexico

Recognition of the importance of members of theCulex pipiens species complex as vectors of differ-ent diseases has been increasing during the last fewyears, mainly because they are involved in thetransmission of West Nile virus. This motivated usto conduct a study on the predatory and searchingcapacities of the water mite Piona amimitli on lar-val Culex restuans, by examining the regression co-efficient. We studied the mite's preference selectionfor the lst 3 mosquito instars and found that thelst instar was preferred by the mite. During the 2ndtest, 5 nymphs, 5 males, and 5 females of the mitewere exposed to 5 densities of larval Cx. restuans.After 3 replicates, the total number of larvae con-sumed after 24 h was recorded and data were an-alyzed by linear regression and by Hollings's andRogers's functional response models. According toregression coefficients, b = O.983 for nymphs, D :

0.953 for females, and b = 0.999 for males. Search-ing capacities were a : 0.O41 for nymphs, a :

0.041 for females, and a : 0.041 for males, withHollings's and Rogers's values of a : O.2852 fornymphs, a : O.3lO9 for females, and a = 0.2821for males.

Field evaluation of Novaluron (OSCAR 100CE) to control larvae of the malaria vector

Anop he Ie s p s e udop unc tip e nnis inMonterrey, Mexico

Darwin Elizondo-Quiroga, Aaron Medina-Sanchez, Armando Elizondo-Quiroga, Adriane E.

Flores-Suarez, and Ildefonso Fernandez-Salas

Laboratorio de Entomologia Mddica, FCb,Universidad Autonoma de Nuevo Leon,

Monterrey, Mexico

Novaluron (OSCAR 100 CE) is an insect growthregulator with great potential as a supplement totemephos for larval control. Increased reports ofte-

384 Jourutar- oF THE AMERIcAN Moseurro CoNrnol AssocrnnoN Vol. 20, No. 4

mephos resistance after decades of use asainst car-riers of vector-borne diseases in endemiJcountriesjustify the need to evaluate new larvicide alterna-tives. Three dosages of Novaluron in water weretested in the field trial: 0.1, 0.2, and 0.3 ml/m3. Fiftylarvae of the malaria vector Anopheles pseudo-punctipennis were placed in 5O 2-gal (7.6-liter)plastic trays. Trays were positioned in a riverbedand exposed to natural ambient conditions. To bet-ter compare Novaluron effectiveness, a commercialformulation of temephos also was tested. Each dos-age was replicated in l0 trays, including controls.Mortality was checked after 24 h, 48 h, 72 h, andweekly for 7 wk. Examination of results showedhigher and similar mortality for doses at 0.1 and0.3 mVm3. Temephos killed 1007o of larvae at alltime intervals up to 7 wk. Residuality of Novaluronwas determined up to week 7. Novaluron may bea good choice for integrated larval control andwhen applied in rotation may delay larval resis-tance to temephos.

Field trials of Novaluron against Anophelesalbimanus and, An. pseudopuntipennis in

southern Chiapas, Mexico

Juan I. Arredondo-Jim6nez andKenia M. Vald6z-Delsado

Centro de Investigaci6n de Paludismo, Instituto deSalud Publica, Chiapas, Mexico

Biorational agents, which are alternatives to syn-thetic chemical larvicides, are safer to humans,nontarget organisms, and wildlife. Among these,insect growth regulators are products that inhibitmolting or synthesis of chitin. Novaluron, a novelchitin-synthesis inhibitor, recently has been evalu-ated against agricultural pests, but informationabout its effect against mosquitoes is limited. Thisproject aimed to conduct World Health Organiza-tion Pesticide Evaluation Scheme phase II studiesof Novaluron (Rimon l0 EC, Makhteshim, Israel)against the malaria vectors Anopheles albimanusand An. pseudopunctipennis. Studies were conduct-ed during August-October 2003 by using I m2 X0.4-m sun-exposed plots. Resulting 99Vo letl:lal con-centration (LCnn; X : 3.33 mg/liter), 2x, and 3Xdosages were tested in triplicate. Three types ofcontrol plots were prepared: temephos (Abate and#61650; pellets 57o, Clarke, Roselle, IL) at 2O mg/liter; untreated plots where apparent fish predatorsof insects were manually eliminated; and untreated,undisturbed plots. Residual effect was evaluated byplacing floating cages with 25 3rd- to 4th-stage lar-vae (2 per plot) and assessing natural larval popu-lation trends of An. albimanus. Through 5 wk,IOOVo mortality was observed with all concentra-tions of Novaluron and IOOVo reduction of adultemergence of natural populations has been ob-

served. Temephos has also produced the same ef-fect.

Field trials of Bacillus thuringiensis israelensispolymer-based granular formulation with

C u le x quinqu efas ciatu s

Yesika L. M6rquez-Garcia, Cindy GuadelupeMiirquez-de la Rosa, Ariadna Rodrfguez-Castro,

Ma. Guadalupe Maldonado-Blanco, Luis J. GaldnWong, and Humberto Quiroz Martinez

Laboratorio de Entomologia, Facultad de CienciasBiol1gicas, Universidad Aut6noma de Nuevo Le6n,San Nicolds de los Garza, Nuevo Ledn: and De-partamento de Microbiologia e Inmunologia, Fa-

cultad de Ciencias Biol6gicas, UniversidadAut6noma de Nuevo Le6n, Mexico

A polymer-based granular formulation of Bacil-Ius thuringiensis israelensls was evaluated for itsefficacy against larval Culex quinquefasciatus in45-m'� permanent ponds in the Pesqueria River.Treatments included active ingredient (unformulat-ed and formulated) and untreated controls. Larvalabundance for several posttreatment periods wasanalyzed through 27 days. When larval abundanceduring sampling dates was analyzed, statistical dif-ferences were found among treatments after 2ldays after treatment. The formulated active agree-ment was the best treatment. According to our re-sults, the possibility of using polymer-based gran-ular formulation over conventional mosquitocontrol methods is now available.

Field evaluation of Bacillus thuringiensis subsp.israelensis polymer formulations in comparison

with unformulated active ingredient

Erick Iviin Mel6ndez L6pez, Violeta AriadnaRodriguez-Castro, Luis Jesfs Gal6n-Wong,

Humberto-Quiroz-Maftinez, and Maria GuadalupeMaldonado-Blanco

Laboratorio de Microbiologia Industrial, Depar-tamento de Microbiologfa e Inmunologia, and La-boratorio de Entomologia, Departamento de Zool-ogia de Invertebrados, Facultad de CienciasBiol6gicas, Universidad Aut6noma de Nuevo Le6n,

San Nicolds de los Garza, Nuevo Le6n, Mexico

A technical powder of Bacillus thuringiensissubsp. israelensis (Bti) was obtained by fermenta-tion. After the Bti was evaluated against larval Cu-lex quinquefasciatus collected from field, it wasformulated with 2 natural polymers and evaluatedagainst mosquito larvae in 200-liter plastic contain-ers, in a random square design with 3 treatmentsand a control, applied at dosage of 13.7 mg/liter.Total larval population densities were recorded ev-ery 3-4 days after treatment by taking 10 dipper

Decsrr,rssn 2004 Moseurro Vecron Cotrnor- alo Brolocy IN LelN AMERTCA-A Fourrenrm Svrrapostutvt 385

samples from each treatment. Examination of theresults showed significant larval reductions of Ae-des aegypti and Culex sp. with 2 of the Bri polymerformulations compared with the control for morethan 60 days after treatment. In contrast, a treat-ment with unformulated Brl powder showed toxicactivity for only 3-6 days after treatment.

Biochemical characterization of insecticideresistance in a population of adult

Aedes aegypfi (L.) in the Baja CaliforniaPeninsula, Mexico

Adriana E. Flores-Suarez, Walter Abeldaflo-Vasquez, Ildefonso Femandez-Salas, MohammadH. Badii, William Brogdon, William C. Black IY

and Barry J. Beaty

Laboratorio de Entomologia Medica, Facultad deCiencias Biologicas, Universidad Autonoma deNuevo Leon, Monterrey, Mexico; EntomologyBranch, Division of Parasitic Diseases, NationalCenter for Infectious Diseases, Centers for DiseaseControl, Atlanta, GA; and Arthropod InfectiousDisease Laboratory, Department of Microbiology,

Colorado State University, Fort Collins, CO

A discriminant dosage of permethrin active in-gredient at 172 1t"g/ml was used to select individualAedes aegypri. Mosquitoes were collected from 4different municipalities located in northern andsouthern sectors of the Baja California Peninsula.Individuals were selected based on the presence ofsimilar responses to insecticide. We exposed groupsof 90 female Ae. aegypti to a discriminant dose,and after producing 5O7o mortality, individualswere divided into 2 categories: dead and survivors.Members of each of these groups were dissected toseparate the head, thorax, and abdomen. Biochem-ical testing was performed on the head and thoraxto determine enzyme activity, such as that of alpha-and beta-esterases, glutathion-S-transferase, acetyl-cholinesterase, insensitive acetylcholinesterase, andmixed-function oxidases. Final results were com-pared with those from a susceptible New Orleansstrain of Ae. aegypti. All populations that we stud-ied consistently showed presence of alpha-esteras-es. Beta-esterases, the main resistance mechanismin permethrin-selected populations, although pre-sent in high proportions, did not reveal a clear pat-tern of its effect. Activity of glutathion-,S-transfer-ase appears to be the principal mechanism in thesurvivors tested.

Susceptibility of Aedes aegypti (L.) toinsecticides in Nuevo Leon,

northeastern Mexico

Gustavo Ponce-Garcia. Adriana E. Flores.Mohammad H. Badii, Ma. Luisa Rodriguez-Tovar,

and Ildefonso Ferniindez Salas

Laboratorio de Entomologfa Mddica, Facuhad deCiencias Biol6gicas, Universidad Autonoma de

Nuevo Leon, San Nicolds de los Garza,Nuevo Leon, Mexico

Dengue control has become more difficult be-cause of the development of resistance in the vectorAedes aegypti to the majority of the commonlyused chemicals. This has occurred with differentgroups of insecticides (e.g., organochlorines, organ-ophosphates, and pyrethroids). In the state of Nue-vo Le6n, Mexico, there is no information about thehistory of development of resistance of Ae. aegyptito the commonly used adulticides. The aim of thisstudy was to investigate the status of susceptibilityand resistance of Ae. aegypti to organophosphates,carbamates, and pyrethroids in 9 municipalities ofNuevo Le6n. Adults were exposed to insecticide-impregnated papers for a period of 2 h, and mos-quito mortality was evaluated every 5 min, with thefinal reading being taken at the end of 24 h. Probitanalysis was used to generate median lethal time(LTro) values. The insecticides used were O.lVo pro-poxn4 5Vo malathion, O.757o permethin, O.O57odeltamethrin, and O.OSVo lambdacyhalothrin. Del-tamethrin gave the lowest LTro value, ranging be-tween 8.2'7 min (Escobedo) and 16.34 min (Villade Santiago). On the other hand, propoxur pro-duced the highest LTro values, ranging between94.41 milr (Linares) and 139.46 min (Villa de San-tiago).

Assessment of damage caused by Tapinomamel.onocephalum (Hymenoptera: Formicidae)

on eggs of Aedes aegypti underlaboratory conditions

Omayda P6rez-Insueta, Rafl Gonz6lez-Broche,Juan A. Bisset-Lazcano, Agustin Navarro-Ortega,

and Zulema Menendez-Diaz

Instituto de Medicina Tropical "Pedro Kouri,"La Habana, Cuba

In Cuba, few studies have been conducted onTapinoma melanocephalum, an ant that apparentlydamages cultivated sugar cane, citrus fruits, andcoffee trees. The present study evaluates, for thelst time, this ant's behavior in the insectary. Paperstrips containing 100 eggs of Aedes aegypti wereplaced in 3 randomly selected sites along whichants passed (right floor, left floor, and on mosquitocages), with 3 replicates. Eggs belonged to 2 dif-ferent oviposition times (i.e., those laid within theprevious '24h and those stored in the laboratory for8 months). The latter group of eggs was collapsedand dehydrated. After 24 h, tlre egg-containing pa-per strips were collected and examined with a ste-reoscopic microscope and the eggs were counted.Data were analyzed and results confirmed that antspreyed on eggs from both groups but caused moredamage to the recently laid eggs. Chi square andKruskal-Wallis tests were conducted for the vari-

386 JounNar- oF THE AMERTCAN MoseurTo CONTROL AssocnnoN Vor-. 20. No. 4

able "site" and its replicates. No significant differ-ences were observed. A Z-test was calculated tocompare proportions for the variable "age ofeggs," which showed a marked preference for re-cently laid eggs regardless of the site where theyhad been placed.

Mosquitoes (Diptera: Culicidae) fromOaxaca, M6xico

Jorge Pascual Martinez Mufloz, Josefina CeciliaTrujillo Garcia, and Gloria Isabel Flores Martinez

Laboratorio Estatal de Salud Publica,Oaxaca, Mexico

From a medical point of view, mosquitoes arevery important because several species take bloodmeals from vertebrates, including humans, andmembers of several genera (e.9., Anopheles, Aedes,and Culex) transmit diseases, including dengue,malaria, and encephalitis. Our objectives were toidentify and prepare a checklist of the mosquitoesof Oaxaca State in southern Mexico. All identifl-cations were made of larval mosquitoes that hadbeen collected from July 1997 to July 2003 duringthe entomological surveillance program conductedby vector control personnel from the State Secre-tary of Health. Mosquito larvae were preserved inlOVo ethyl alcohol and sent to the Oaxaca State Pub-lic Health Laboratory for identification. We identi-fied 28 species in the following 10 genera; AedesMeigen, Ochlerotatus Lynch-Arribalzaga, CulexLinnaeus, Anopheles Meigen, Limatus Theobald,U ranotaenia Lynch-ArribaIzaga, Psorophora Robi-neau-Desvoidy, Toxorhynchite s'fheobald, H aema-gogas Williston, and Wyeomyia Theobald. Aedes ae-gypti, Ochlerotatus epactius, and Culexquinquefasciatus wete the species with the broadestdistributions in Oaxaca.

Aquatic Diptera as a potential pathological riskin three recreation parks along the "La Silla"

River in Guadalupe, Nuevo Le6n, M6xico

Alejandra Pefra-Estrada, Jorge Abraham Flores-Mellado, Humberto Quiroz-Martfnez, Ariadna

Rodriguez-Castro, Pedro Garza Tievifro, RodrigoEscobedo, and Horacio Garcfa Quezada

Laboratorio de Entomologia, Facultad de CienciasBiol6gicas, Universidad Aut6noma de Nuevo Le6n,San Nicolds de los Garza and Presidencia del Mun-

icipio de Guadalupe, Nuevo Le6n, Mexico

Knowledge of aquatic Diptera in public parksgives several benefits. One of these is informationabout the entomological risk to public healthcaused by the Diptera that transmit diseases of hu-mans. This work was focused on determining thediversity of Diptera and locating the possible breed-

ing sites of vectors in 3 recreational parks along theLa Silla River in Guadalupe, Nuevo Leon, Mexico.Samples were collected every 15 days betweenMay 22, 2OO2, and September 18, 2003. Sampleswere obtained by using a triangular net by intro-ducing it into the river and removing I m, of sub-strate. The samples were placed in a plastic bag andpreserved in 96Vo ethyl alcohol and transported tothe laboratory for identification and counting. From30 field collections, we obtained a total of 4,365dipterans in 5 families (Chironomidae, Culicidae,Ceratopogonidae, Dolichipodidae, and Empididae)and 5 genera (Beardius, Culex, Hemerodromia,Atrichopogodon, and Glutops). The highest densitywas that of Beardius, with 4,350 specimens col-lected. A single larvae of Culex was collected,which was the only species with a potential risk tohumans as a vector of West Nile virus.

Predictive value of environmental variablesand mosquito abundance over malaria

morbidity in Bolivar State,southeastern Venezuela

Jorge Moreno and Yasmin Rubio-Palis

Instituto de Altos Estudios "Dr. Arnoldo Gabal-d6n," Maracay, VeneTuela; Centro de Investiga-ciones de Campo "Dr. Francesco Vitanza," Tum-eremo, Venezuela: and Bolivar and BIOMED,

Universidad de Carabobo, Maracay, Venezuela

During 2OOO,29,887 cases of malaria, which wasconsidered an epidemic level for this disease, werereported in Venezuela. This phenomenon seemed tobe linked to local climate changes, which princi-pally increased temperature and affected rain pat-terns. The municipality of Sifontes in Bolivar Statein southeastern Venezuela is considered a high-riskmalaria area. To identify malaria-predictive envi-ronmental variables at the local level in a definedperiod of time, all-night human-landing catcheswere made in this area monthly from January 1999to April 2000. Multiple regression analysis ofmonthly mosquito abundance plus environmentalvariables obtained at local stations indicated thatthe predictive variables of relative humidity 1P :

0.036) and mosquito abundance (P : 0.049) hadsignificant statistical effects on variability in themonthly parasite index (MPI). Likewise, the P-val-ue suggested that rainfall (P : O.I52) and meantemperature (P : 0.174) variables did not have pre-dictive value for the MPI in this area. Additionally,variance analysis (F : 4.14, P : 0.031) supportsthe regression analysis between the environmentalvariables and MPI. The importance of these cli-matic variables over the malaria morbidity is dis-cussed. This study was supported by project VEN/96102l-023 and Inter-American Institute for GlobalChange Research (IAI-CRN).

DecsMgsn 2004 Moseurro VEcroR CoNrnor- eNo Brolocy IN LAIN AMsRrce-A FoURTEENTH Svuposrurra 387

Anophelines in the municipality ofVillavicencio, Department of Meta, Orinoquia

Region, Colombia

H. L. Brochero, L. S. Buitrago, G. Rey, G. Fl.Mosquera, and V. A. Olano

Laboratorio de Entomologia, Instituto Nacional deSalud, Bogota, Colombia; Unidad de Entomologia.Secretaria de Salud de Meta, Meta, Colombia; andFacultad Ciencias de la Educaci6n, Universidad

Francisco Josi de Caldas, Bogota, Colombia

Collections of adult and immature anophelineswere made to study their behavior and habitat pref-erences at 11 locations in the municipality of Villa-vicencio, Department of Meta, Orinoquia Region,Colombia. Urban and rural areas were sampledfrom August to November 2OO2 and in April 2003.Adult mosquito collections were made between1800 and 2100 h by using human bait, Shannontraps, animal bait, and resting sites and stored untilisofamilies were obtained for their correct identifl-cation. In order of abundance, the species collectedwere Anopheles marajoara, An. rangeli, An. bra-ziliensis, and An. darlingi. Biting rate peaks oc-curred in the peridomiciliary area for An. mara-joara between 1900 and 2000 h and for An.darlingi between 18OO and 1900 h, whereas for An.rangeli and An. braziliensis, the peak of extradom-iciliary biting activity occurred between 1800 and1900 h. We characterized 44 breeding sites by tak-ing into account the distance of the site to the near-est house, its physical and chemical aspects, its pe-rimeter, and the species captured. These includedfish ponds (65.9Vo), flooded grazing Iand (6.8l%o),and water drainage canals (6.817o). The remainingsites included streams, water springs, cistems, ex-cavations, ponds, small pools, and swamps withtropical palms ("moriche"). The immature speciescollected at these sites were the same as those col-lected as adults. The most abundant species was An.marajoara, which adapted better to breeding placescharacteized by total exposure to sunlight, by sur-rounding vegetation, and by neutral pH in clear orturbid water. Anopheles marajoara bites inside andoutside human dwellings and was in much greaterabundance compared with the presumed vector ofmalaria in this region, An. darlingi. This behavioris due to adaptations to land-use alterations, irreg-ular control strategies, and invasion of its habitatby human immigrants because of civil unrest. Al-though this species has not been considered a ma-laria vector in Colombia, it has been found infectedwith human sporozoites of Plasmodiun sp. For thisreason, we think that An. marajoara and, An. dar-lingi maintain malaria in this region, the lst as anancillary vector and An. darlingi as the main vector.Control strategies should be directed at developingprimary prevention activities with the community

in order to clear the borders of fish ponds, as wellas alternatives for personal protection.

Larvicidal activity of essential oils on Aedesaegypti (Diptera: Culicidae)

Lucita Aguilera, Juan E. Tacoronte, AgustinNavarro, Maureen Leyva, Marfa T. Cabrera, and

Omar Fuentes

Instituto de Medicina Tropical "Pedro Kouri,"In Habana, Cuba

Dengue and dengue hemorrhagic fever, the mostimportant arboviral disease for humans in theworld, are on the increase in most countries in theAmericas. For many decades, the strategy for con-trol of mosquito vectors was based on the use ofchemicals; however, in recent years alternative con-trol approaches that are more ecologically safe andsustainable have been sought. Essential oils derivedfrom certain plants exhibit toxic effects on manyinsects, including mosquitoes. In this study, weevaluated the larvicidal activity of essential oils iso-lated from leaves of Piper ossanum and Curcumalonga agaitst Aedes aegypti, the principal vector ofdengue in the Americas. Three laboratory bioassaysper essential oil were carried out by following stan-dard World Health Organization methodology. Re-sults were analyzed by probit-log software anddemonstrated that these essential oils exhibited lar-vicidal activity against this mosquito. The medianlethal concentrations (LCros) were 0.057 and0.O257o, and the LCn.s were 0.0076 and 0.OO43Vofor P. ossanum arrd C. longa, respectively. The di-agnostic concentration for each essential oil alsowas calculated. The results were compared withthose obtained in previous studies of essential oilsfrom Eugenia melanadenia and Psidium rotunda-tum agarnst the same strain of Ae. aegypti. The pos-sible implications and future perspectives for theuse of essential oils against field populations arediscussed.

Susceptibility of larval Aedes aegypti toinsecticides in La Antigua, Veracruz, M6xico

Maria Cristina Bobadilla-Utrera, Adriana E.Flores, Ildefonso Fern6ndez-Salas, Javier

Herniindez-Illescas, Ma. Teresa Martinez-Cazares,Aurora Parissi-Crivelli, Alejandro Escobar-Mesa,

and Mauro Loyo-Varela

Laboratorio Estatal de Salud Publica, Servicios deSalud de Veracruz, Veracruz, Mexico; Laboratoriode Entomologia Medica, Facultad de CienciasBiologicas, Universidad Aut6noma de Nuevo Lton,Monterrey, Mexico; Sertticios de Salud de Vera-

cruz, Xalapa, Veracruz Mexico

The insecticide resistance problem along with the

388 Jount.lel or tHe AventcaN Mosquno CoNTRoL AssocrATroN Vor. 20, No. 4

absence of a domestic hygiene program in VeracruzState contributes to the high prevalence of denguecases there. The objective of this study was to de-termine the level of susceptibility of Aedes aegyptifrom several municipalities to DDT, temephos, mal-athion, permethrin, cypermethrin, and biphenthrin.We used World Health Organization (WHO) bio-assay methodology. The results were analyzed bymeans of probit analyses by using WHO and max-imun likelihood methods. Median lethal concentra-tions (LCros) for DDT werc O.7O44 and 0.7O42 ppmfor La Antigua and Cardel municipalities, respec-tively, and LCn, values were 25.9938 and 26.7568ppm for Salmoral and San Pancho municipalities,respectively. The LC.o values for temephos were0.003716 ppm for Cardel and O.OO3773 ppm forSalmoral, whereas the LCr. values were 0.018506and 0.018383 ppm for Salmoral and San Pancho,respectively. The LC.o values for malathion were0.160403 and O.l7l23O ppm for populat ions ofAe.aegypti from Cardel and San Pancho, respectively,and the LCr. values for Cardel and San Panchowere 0.36114 and 0.429544 ppm, respectively. TheLCro values for permethrin were 0.000044 ppm forSalmoral and San Pancho and 0.000045 ppm forCardel. The LCr. values were 0.0003 ppm for Car-del and 0.000306 ppm for La Antigua. The LCrofor cypermethrin was 0.00002 ppm for La Antiguaand Cardel and 0.0001 1 ppm for San Pancho,whereas the LCn, was 0.000106 ppm for San Pan-cho and 0.000112 ppm for Salmoral. The LC.o val-ues for biphenthrin were 0.000041 ppm for Cardeland 0.000044 ppm for Salmoral and San Pancho.The LCn, values were 0.00021 and 0.000239 ppmfor Cardel and Salmoral, respectively.

Preliminary observations on thesusceptibility of Lutzomyia evansi to

fenitrothion and lambdacyhalothrin in TrujilloState, Venezuela

L. Alvarez. Y. Duran. M. Oviedo. and L. Villareal

Universidad de los Andes, Trujillo, Venezuela

Lutzomyia evansi is considered an alternativevector of visceral leishmaniasis in Colombia andVenezuela. In Trujillo State, Venezuela, a study onthe bionomics of this species has revealed that itappears to be associated with the main focus ofvisceral leishmaniasis, with rates of natural infec-tion of O.237o. This species is anthropophilic withcharacteristic intra- and peridomestic behavior. Byusing this information, we studied the susceptibilityof this species to selected insecticides under exper-imental conditions to establish the baseline suscep-tibility to fenitrothion and lambdacyhalothrin. Lut-Tomyia evansi was collected in Pajones (9"30'28"N,70"33'19'TV), where no insecticides are used. Thebioassay was carried out by residual exposure. Theresults revealed that these insecticides have a hish

toxicity against this species; with a diagnostic con-centration of O.Ol8Vo for fenitrothion and O.OO63Vofor lambdacyhalothrin. The median lethal concen-tration (LC.o) and LC* were 0.012 and O.OSVo, re-spectively, for fenitrothion, and were 0.0004 andO.0Ol77o, respectively, for lambdacyhalothrin.These results are important because this is the lsttime that lethal concentrations have been deter-mined for L. evansi and they can be used to estab-lish comparisons with other populations of L. evan-si originating from areas of high insecticidalpressure.

Aedes aegypli in Brazil:eradication really happens?

Jos6 Eduardo Bracco, Margareth de Lara Capurro,Ricardo Lourengo-de-Oliveira, and

Maria Anice Mureb Sallum

Faculdade de Sartde Prtbhca, USP, Brazil

The mosquito Aedes aegypti was introduced intoBrazil for the lst time during the lTth and 18thcenturies with the slave traffic from Africa. In the1950s, there was an eradication campaign in SouthAmerica and Ae. aegypti was considered eradicatedin many countries, with Brazil among them, but in1959, the speices was reported to be present in Bra-zil again. We analyzed data on 153 American mos-quitoes sequenced for a 361-base-pair fragmentfrom the mtDNA NADH4 gene. Molecular varianceand nested clade analysis indicated the presence of2 major groups, separated by 8 mutational steps(95Vo confidence limit). One of these groups (groupl) is related with Senegal populations (Africa),whereas the other group (group 2) is related to oth-er African, Asiatic, and American populations. Theanalysis showed that group 2 was 2-fold more poly-morphic (F1 : 0.8131) than group 1 (H : 0.4033)and from analysis of variance, it was found that72Vo of the variability occurs between these 2groups. Examination of these data suggests thatthere were at least 2 introductions of Ae. aegyptiinto South America, with the former from Senegalthat was supposed to be eradicated and a later onefollowing the Africa-Asia-North America route.

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