A Record of Mosquito Species Collected during a Larval Survey in Argentina and Uruguay (diptera, Culicidae)’

Mosquito larvae were collected in 3 provinces in Argentina and 1, in Uruguay, to search for pathogens which might serve as biocontrol agents. In all, 411 larvae belonging to 19 species were mounted and identified. They include 7 new province records for Argentina and a new country record for Uruguay. In Dec. 1984, three of us (JJB, EIH, JJG) collected mosquito larvae in the Provinces of Formosa, Mendoza and Misiones in Argentina and in the Province of Salto, Uruguay, in search of mosquito pathogens which might be useful in biological control. In fact, several organisms were encountered which are being investigated and will be the subject of another paper. Here we are recording the habitats sampled and the species of mosquitoes encountered which will further our understanding of the distribution and bionomics of the species collected. We are reporting 19 species, 14 in Formosa, 5 in Mendoza, 2 in Misiones and 3 in Salto. A total of 411 larvae were collected, mounted and identified. They include 7 new province records for Argentina and 1 new country record for Uruguay. It is interesting to note that species collected during this study in Formosa were not found in Mendoza andvice versa. Some understanding of the geography of the Provinces where the collections were made will help to comprehend the fauna1 differences. The numbers in parentheses after each species name given below indicate the quantity of larvae collected. ‘This study was suppo rted in part by grant No. INT8307889 from the National Science Foundation. 2Research Entomologist, International Center for Public Health Research, University of South Carolina, P.O. Box 699, McClellanville, SC 29458. 3Microbiologist, U.S. Department of Agriculture, Agriculture Research Service, Insects Affecting Man and Animals Laboratory, P.O. Box 14565, Gainesville, FL 32604. 4Entomologist, deceased, U.S. Department of Agriculture, Agriculture Research Service, Insects Affecting Man and Animals Laboratory. 5Researcher, Buenos Aires Provincial Research Commission, Centro de Estudios Parasitologicos y de Vectores, Calle 2, No. 584, (1900) La Plata, Argentina. Formosa Province is between 23 and 27”s latitude. It is in the Gran Chaco area, a vast alluvial plain having poor drainage. It is covered by forests, grasslands and marshes. Formosa City L26.07 S lat.; 58.14 W long.] with an elevation of about 200 m is a river port on the Paraguay River. Six larval habitats, all within a short distance of Formosa City, were sampled with the following results. 1) From a grassy pond with fresh clear water in a broad, shallow ditch in full sun, next to a fallow rice field, were dipped: Cc&x educator Dyar and Knab (1) NEW PROVINCE RECORD, CuZtzpilosus (Dyar and Knab) (1) NEW PROVINCE RECORD, Umnotmia lowii (l), Psorophora Sp. A (3). 2) In a lagoon with clear fresh water, much aquatic vegetation, including water hyacinth and cattails, in full sun were collected the following: Aedeomyia squamipennis Lynch Arribalzaga (lo), Anopheles albitarsis Lynch Arribalzaga (74), An. evansae (Brethes) (33),An. oswaldoi (Peryassu) (4), An. triannulatus (Neiva and Pinto) (5), C&x bastagatius Dyar and Knab (15) Cx. taeniopus Dyar and Knab (1) NEW PROVINCE RECORD, Psorophora Sp. A (3). 3) In a watering trough in a horse corral in full sun containing turbid water only Psorophora cinguZatu (Fabricius) (14) NEW PROVINCE RECORD was taken. 4) In a stagnant ground pool in the same horse corral under trees with turbid water and no vegetation were found Ps. cingulata (14) and Culex mollis Dyar and Knab (1) NEW PROVINCE RECORD. 5) In an open septic tank in full sun and 6) in a treehole 1 m above ground level, about 45 cm in diameter and with dark brown water only Cr.&.x quinquefusciutus Say (40) and (12), respectively, was retrieved. Mendoza Province is between 33 and 38”s latitude. It is a foothill province adjacent to the high Andes Mountains. Much of it is arid or semiarid with an extensive saline basin in the east into which several rivers flow. Agriculture in the province is supported by irrigation schemes. Mosquitoes were collected in the environs of Mendoza City [32.48 S lat.; 68.52 W long.] at an elevation of 761 m. Three larval habitatswere sampled. Because of its dry climate, salt and other minerals are common in the soil and although salinity was not measured, it is assumed that sites 2 and 3 below were saline since larvae dipped from them are known to breed in brackish water (Belkin et al. 1968, Bachmann and Casall962a, b). 1) From rainwater pool among brushy shrubs with algae in full sun were taken Aedesfluviat (Lutz) (1) NEW PROVINCE RECORD, Ae. scapularis (Rondoni) (18), Ae. serratus (Theobald) (18) NEW PROVINCE RECORD. 2) From pools in aqueduct with brownish water devoid of vegetation in full sun were dipped Cule~ brethesi Dyar (17) and Cm tramazayguesi Duret (44). 3) From a roadside ditchwithvegetation in full sun was collected Cm brethesi (6). Misiones Province is located between 25 and 29”s latitude and forms a narrow corridor extending northeast between Paraguay and Brazil. A remarkable landmark is the “Cataratas de Iguazu”, one of the world’s most impressive water falls. It is located at the tricorner where Brazil, Paraguay and Argentina meet. Mosquito collections were made in the nearby town of Iguazu [25.3 S lat.; 54.2 W long.]. Discarded tires under shade in an urban area yieldedAe.fluviatiZis (22) and Culexquinquefasciatus Say (26). Salto Province, Uruguay, located between 30 and 32% latitude, has rolling hills of the “Cuchilla de Haedo” with rocky soil which makes the region well suited for cattle and sheep ranches. Two collections were made north of the capital city, Salto, near a hot springs resort area called “Termas de Arapey” [30.5 S lat.; 57.3 W long]. 1) In a quiet pool at the edge of a stream in full sun were dipped An. albitarsis (4) and An. evansae (6); 2) From a small lagoon containing mineral water, grassy vegetation in partial shade were collected Cr. brethesi (3) NEW COUNTRY RECORD. COMMENTS ON SEVERAL SPECIES Anopheies albitarsis: The albitarsis subgroup of the Albi~ursis group of Nyssorhynchus consists ofAn. albitarsis, An. marajoara Galvao and Damasceno (Linthicum 1988) and a newly described form,An kaneomm Rosa-Freitas (RosaFreitas 1989). Distributionally, An. azbbitarsis is confined to the southern temperate region of South America, An. marajoara [formerly allopha Peryassu] extends from Brazil north to Honduras (Linthicum 1988) and deaneorum is at present known only from the States of Rond6nia and Acre in western Brazil. Cukxquinquefasciatus: Mitchell et al. (1984) showed that true Cm pipiens Linnaeus was present in southern Argentina. They reviewed what was known about the distribution of thepi@ens complex in the country. Also, Brewer et al. (1987) reported that both truep@iens andquinquefasciatus occur in the Province of Cordoba as well as the hybrid, i.e., infrasubspecies C&X pallens Coquillett. We have detected some differences in the specimens from Formosa and those from Iguazu, based on the measurement of the siphon index (SI). Brogdon (1981) supported the use of the siphon index as a morphological tool for separating CX quinquefasciatus [SI = 3.05-3.671 from fi p@iens [SI = 42-4.751 while their hybrids, Cm p&ens had intermediate values [SI=3.724.191. Measurements of 40 larvae from Formosa showed an average SI of 3.42 with a standard deviation of 0.28, while the SI of the 26 larvae from Iguazu, Misiones Province, averaged 4.04 with a standard deviation of 0.23. Based on Brogdon’s concept we speculate that the population in Formosa is true quinquefusciatus while the Misiones population represents the hybrids,