[Mass production of Romanomermis iyengari (Nematoda: Mermithidae) applied to anopheline breeding sites in Boa Vista (Roraima), Brazil]. / Producción masiva de Romanomermis iyengari (Nematoda: Mermithidae) y su aplicación en criaderos de anofelinos en Boa Vista (Roraima), Brasil.

In order to begin mass producing the nematode Romanomermis iyengari Welch, a bioprocessing plant was designed and set up on the grounds of Universidad Federal in the State of Roraima, Brazil, after reaching an agreement with the State's Health Department. The objective of this paper was to establish the basic process for mass breeding the parasite in order to apply it to anopheline breeding sites. Cultures were obtained at a rate of 68 during every seven-day cycle, making for a total of 272 cultures a month. Before treatments were applied in the field, laboratory tests were conducted that showed the great susceptibility of anopheline larvae to infestation by R. iyengari, with parasitism rates ranging from 71 to 98%. In order to assess the parasitizing capacity of R. iyengari in actual field conditions, 12 natural anopheline breeding sites were chosen, each ranging in size between 50 and 450 m2. The species Anopheles albitarsis Lynch-Arribálzaga and Anopheles rondoni Neiva-Pinto were detected there, at densities that ranged from 34 to 66 larvae/m2. The biolarvicide was sprayed in all 12 breeding sites with a domestically manufactured pump set at a pressure of two atmospheres and a dose of 2,000 preparasites/m2. Seven days after treatments were performed, anopheline populations were markedly reduced (85 to 97%). Results obtained point to the feasibility of using R. iyengari to control larval populations of both species of anophelines.

[Susceptibility of Aedes aegypti larvae to parasitism by Romanomermis culicivorax in laboratory and field conditions in Oaxaca, Mexico]. / Susceptibilidad de las larvas de Aedes aegypti al parasitismo por Romanomermis culicivorax en condiciones de laboratorio y de campo en Oaxaca, México.

In June 1996 in the state of Oaxaca, Mexico, larvae of the mosquito species Aedes aegypti were exposed to infective preparasites of the nematode Romanomermis culicivorax, Ross and Smith, in the laboratory and in the field. For the laboratory experiments larvae in instars I-IV were used; they had been collected in natural reservoirs. The laboratory experiments were carried out in triplicate, with 100 larvae of each larval stage per experiment. Three preparasite application dosage ratios were tested: 5, 10, or 15 preparasites per mosquito larva. For the field studies 13 A. aegypti outdoor breeding sites were used, with larvae in instars I-IV and a 15:1 preparasite dosage ratio. With the laboratory experiments, an increase was observed in the average infestation of the larvae as the preparasite application ratio was increased from 5:1 to 15:1. With a 10:1 ratio, the rates of parasitism were 100%, 100%, 85%, and 74% in the larvae in instars I, II, III, and IV, respectively; for the 15:1 preparasite ratio, parasitism rates were 100%, 100%, 90%, and 79%, respectively. The field tests with the 15:1 preparasite dosage ratio in the 13 outdoor reservoirs produced parasitism rates of 80% to 98%, thus demonstrating the susceptibility of this species of mosquito to parasitism by R. culicivorax in Oaxaca, Mexico.

[Pathogenic effect of the nematode parasite Romanomermis iyengari(Nematoda: Mermithidae) in Aedes aegypti mosquito larvae (Diptera: Culicidae) under laboratory conditions in the state of Oaxaca, Mexico]. / Efecto patogénico del nematodo parásito Romanomermis iyengari (Nematoda: Mermithidae) en larvas del mosquito aedes aegypti (Diptera: Culicidae) en condiciones de laboratorio en el Estado de Oaxaca, México.

Laboratory tests with waters from Aedes aegypti Linneaus (1762) breeding places were made to determine the pathogenic effect of the mermithid nematode Romanomermis iyengari Welch 1964 in mosquito larvae of this species. According to the results obtained, the administration of a dosage of 10:1 (10 preparasitics per mosquito larvae) showed levels of parasitism of 90, 93, 91, and 85% in mosquito larvae in the I, II, III, and IV stage, respectively. With the highest dosage of 20:1 (20 preparasitics per mosquito larvae) there were obtained levels of parasitism with values of 98, 97, 93 and 89% among larvae in the I, II, III, and IV stage, respectively. Generally, the values of the physical and chemical parameters such as pH, conductivity, oxygen, and chlorides calculated in these waters did not affect apparently the infective capacity of the preparasitics of R. iyengari.

[The susceptibility of Anopheles pseudopunctipennis larvae to parasitism by the nematode Romanomermis iyengari (Nematoda: Mermithidae), the state of Oaxaca, Mexico]. / Susceptibilidad de las larvas de Anopheles pseudopunctipennis al parasitismo del nematodo Romanomermis iyengari (Nematoda: Mermithidae), Estado de Oaxaca, México.

Mosquito larvae of the species Anopheles pseudopunctipennis Theobald 1901 were studied under laboratory and field conditions to evaluate the level of susceptibility to the parasitism of nematode Romanomermis iyengari Welch 1964. Doses of 5:1 and 10:1 and development stage II larvae collected in natural reservoirs were used for the laboratory assays. A dose of 1,000 preparasitic agents/m2 was applied to field trials. The results of the lab and field tests yielded high levels of infestation in larvae with values ranging from 90 to 100% and from 85 to 95%, respectively. A marked reduction of the larval densities was observed in the 5 treated reservoirs seven days later, which showed an elevated susceptibility of the anopheline species to mermithid parasitism.

Reduction of mosquito larval densities in natural sites after introduction of Romanomermis culicivorax (Nematoda:Mermithidae) in Cuba.

Romanomermis culicivorax Ross & Smith became established in 4 of 6 treated sites and produced high levels of infection in Anopheles albimanus Wiedemann, Culex atratus Theobald, Psorophora confinnis Lynch-Arribálzaga, and Uranotaenia sapphirina Oster-Sacken mosquitoes for 9 wk in 1993. Mean levels of southern house mosquito parasitism ranged from 82 to 83% for Culex quinquefasciatus Say, at 2 sites, from 89 to 95% for An. albimanus at 4 sites, and from 78 to 80% at 2 sites for Cx. atratus, Ps. confinnis, and Un. sapphirina. Results indicated that R. culicivorax has potential use as biological control agent against mosquitoes in several different habitats in Cuba.

Demostración de la actividad biolarvicida de Romanomermis iyengari (Nematoda: Mermithidae) en condiciones de laboratorio / Demostration of the biolarvicidae activity of Romanomermis iyengari (Nematoda: Mermithidae) in laboratory conditions

Se llevaron a cabo pruebas de laboratorio para demostrar la eficacia del mermítido Romanomermis iyengari como agente biorregulador de larvas de Culex quinquefasciatus y Anopheles albimanus vectores de filariasis y de malaria en el área del caribe. Se probaron dosis de preparasíticos a larvas hospederas de 3:1, 5:1 y 10:1, encontrandose que las especies de mosquitos ensayadas se comportaron de manera similar presentando medias de infectación más elevadas a medida que se incrementaba la dosis. Fue demostrando la selectividad de R. iyengari por larvas de los estadíos más jóvenes de ambas esapecies, las cuales mostraron altas tasas de infectación y los porcentajes más altos de parasitismo. Los ensayos realizados para valorar la edad de los cultivos del mermítido con el objeto de determinar el tiempo óptimo de almacenamiento, demostraron que los preparasíticos provenientes de cultivos almacenados durante 6 semanas a temperatura ambiente arrojaron los más altos índices de infectación en larvas de C. quinquefasciatus del insectario. Estos resultados permitieron concluir que R. iyengari puede ser utilizado como agente potecial de control biológico, para poblaciones larvales de mosquitos especialmente de los estadíos más jóvenes

Release of Romanomermis iyengari (Nematoda:Mermithidae) to control Aedes taeniorhynchus (Diptera:Culicidae) in Punta del Este, Isla de la Juventud, Cuba.

Preparasites of Romanomermis iyengari Welch were applied at the rate of 1,000 preparasites per square meter of surface area in 5 natural breeding sites in carbonate rock depressions to control Aedes taeniorhynchus Wiedeman larvae. Larval parasitism averaged 100, 97, 81, and 80% in 1-4 instars, respectively. Three of 5 sites produced parasitism in excess of 90%. The range of salinity and water depth had little influence on the levels of parasitism. Ae. taeniorhynchus density was reduced from 78 to 96% at the 5 sites 8 d posttreatment.

[Mass breeding of Romanomermis culicivorax (Nematoda: Mermithidae) in the tropical conditions of Cuba]. / Cría masiva de Romanomermis culicivorax (Nematoda: Mermithidae) en las condiciones tropicales de Cuba.

To develop the process of mass production on a large scale of the parasite nematode Romanomermis culicivorax Ross and Smith, 1976, under the control tropical conditions of Cuba, it was taken into consideration the standardization of a certain number of variables, such as: utilization of eggs in the process of infectation, dosage, types of water, types of substrate, temperature, culture methods, and storage methods of culture batches. High performances in nematoda and approximately the same amount of females and males were obtained when mosquito larvae of the species Culex quinquefasciatus Say, 1823, were exposed to parasite's infective larvae.

[An oviposition study of the nematode parasitic on Culicidae Romanomermis iyengari in the laboratory]. / Estudio de la oviposición del nematodo parásito de culícidos Romanomermis iyengari en el laboratorio.

Laboratory studies allowed determine that female Romanomermis iyengari Welch, 1964, had a reproductive potential of 1975, 29 eggs in an average time of 21,76 days in distilled water with pH of 4.5 and a temperature of 25 +/- 2 degrees C. It was found that females of this nematode began oviposition in an average time of 14.65 days from the moment of emersion of postparasites of the host larvae. In studying the embryonic development, it was observed that the time elapsed from oviposition to egg hatching and the emersion of preparasites was 290,74 hours. It was determined that the optimum time to begin the exploitation of cultures and obtain a greater yield of preparasites under laboratory conditions is the sixth week of storage.

[Application of a mermithid nematode for the control of mosquito larvae in natural conditions]. / Aplicación de un nematodo mermítido para el control de larvas de mosquitos en condiciones naturales.

Field tests were carried out with the Romanomermis culicivorax nematode (Ross and Smith, 1976) for the control of 3 mosquito species--Anopheles albimanus (Wiedeman, 1821): Culex nigripalpus (Theobald, 1901); and Uranotaenia saphirina (Oster-Sacken, 1868)--in 10 natural reservoirs. The infective nematodes were disseminated in doses of 1 x 10(3) preparasites/m2 of surface area. Increased infestation indices were observed with values ranging from 1.2 to 3.4; mortality percentages fluctuated between 70 and 97% depending on the mosquito species found in the reservoirs. In those reservoirs containing specimens of the 3 species, anophelines showed more susceptibility to parasite infection; culicines showed a lower susceptibility in general. Mosquito larva populations were significantly reduced in the treated reservoirs.

[Fecundity and embryonal development of Romanomermis culicivorax]. / Fecundidad y desarrollo embrionario de Romanomermis culicivorax.

Romanomermis culicivorax (Ross and Smith, 1976) eggs completed the late preparasite curling phase of their embryo development in an average time of 11 days and at a temperature of 25 +/- 2 degrees C. It was also observed that female R culicivorax specimens laid 312 eggs in 13 days, when male and female specimens were placed in a substrate of distilled water with a pH = 4.5.

[The evaluation of the infectious capacity of the parasitic nematode Romanomermis iyengari (Welch, 1964) (Nematoda: Mermithidae) in natural mosquito larval breeding areas]. / Valoración de la capacidad infectiva del nematodo parásito Romanomermis iyengari (Welch, 1964) (Nematoda: Mermithidae) en criaderos naturales de larvas de mosquitos.

Field tests were carried out with the nematode parasite Romanomermis iyengari (Welch, 1964) to fight 3 species of mosquito larvae Anopheles albimanus (Wiedeman, 1821); Culex nigripalpus (Theobald, 1901); and Culex quinquefasciatus (Say, 1823) in three ecologically different natural mosquito reservoirs. The release of the nematode embryos (infective stage) in the above-mentioned reservoirs was carried out with a Holder-planta 5 manual sprayer, at 2 atm, and an application dose of 1000 parasite embryos/m2. The parasite embryos were obtained from 6 nematode cultures, soaked in distilled water. Results showed that mosquito larvae were parasitized by R. iyengari as follows: 100% of the A. albimanus and 85% of the C. nigripalpus, in the first reservoir; 85% of the C. nigripalpus, in the second reservoir; and 80% of the C. nigripalpus and 75% of the C. quinquefasciatus in the third one. Thus, the potential use of the nematode parasite Romanomermis iyengari as a biological control agent of mosquito larvae was shown.

[Infective capacity of the parasitic nematoda Romanomermis iyengari (Welch, 1964) (Nematoda: Mermithidae) in mosquito larvae in natural conditions]. / Capacidad infestiva del nematodo parásito Romanomermis iyengari (Welch, 1964) (Nematoda: Mermithidae) en larvas de mosquitos en condiciones naturales.

The effectiveness of the parasitic nematoda Romanomermis ivengari (Welch, 1964) was proved in 3 breeding sites of Anopheles albimanus (Wiedman, 1821) and Culex Nigripalpus (Theobald, 1901) and 2 spillways for 2 oxidation ponds with Culex quinquefasciatus (Say, 1823) larvae, in the Isle of Youth. The results of the experiments showed the infesting capacity of this nematoda species with 80-100% parasitism in A. albimanus and C. nigripalpus larvae, and 75-80% mortality for C. quinquefasciatus. Besides, the recycling capacity of R. invengari, after its introduction, was proved, confirming its possible use in the control of mosquito larvae of medical-epidemiological importance in the Cuban tropical conditions.

[The infective capacity of the nematode Romanomermis culicivorax Ross et Smith, 1976 (Rhabditida: Mermithidae) in mosquito larvae of the species Anopheles albimanus Wiedemann, 1821 (Diptera: Culicidae) under natural conditions]. / Capacidad infestiva del nematodo Romanomermis culicivorax Ross y Smith, 1976 (Rhabditida: Mermithidae) en larvas de mosquitos de la especie Anopheles albimanus Wiedemann, 1821 (Diptera: Culicidae) en condiciones naturales.

An experimental study was carried out in two natural breeding sites of Anopheles albimanus Wiedemann, 1821 in Havana City, in order to test the effectiveness of the nematode Romanomermis culicivorax Ross and Smith, 1976. In one of the breeding sites fresh preparasiticals from eggs recently hatched in cultures were applied at a 10:1 dose, a mean infestation rate being found of mean = 3 with a 97 +/- 0.86% mortality. The second breeding site was treated with preparasiticals 30 hours after their obtention, and a decrease was seen in the larva infestation levels mean means = 1.1 and 76 +/- 0.76% mortality rate.

[The introduction of the larvivorous fish Poecilia reticulata (Peters, 1895) (Cyprinodontiformes: Poeciliidae), a bioregulator of culicids in oxidation ponds and contaminated drainage ditches on the Isla de la Juventud]. / Introducción del pez larvívoro Poecilia reticulata (Peters, 1895) (Cyprinodontiformes: Poeciliidae), agente biorregulador de culícidos en lagunas de oxidación y zanjas contaminadas en la Isla de la Juventud.

The larvivorous fish Poecilla reticulata, internationally known as mosquito larva bioregulators, was introduced in 2 oxidation ponds and 2 ditches containing polluted waters (sewage) without the presence of other fish species, in Isle of Youth, Cuba, in order to control the larva populations of the Culex quinquefasciatus mosquito Say, 1823 in these its main breeding sites. After 2.5 months, such reservoirs were free of mosquito larvae. The fish settled within one year, reaching enough density to be used in other aquatoria.