Application of the pupal/demographic-survey methodology in an area of Havana, Cuba, with low densities of Aedes aegypti (L.).

Between the April and December of 2004, an Aedes aegypti (L.) pupal/demographic survey was conducted in the Playa municipality of Havana. The aims were to identify the key types of container in the production of the adult mosquitoes (and so provide a basis for targeted control) and assess transmission risk in terms of the number of pupae/person. Pupal abundance, as measured in the survey, was compared with traditional Stegomyia indices. The immature stages of Ae. aegypti were only found in 70 of the 15,153 containers that were investigated and the pupae of this species were only seen in 52 of the containers. Ground-level water-storage tanks yielded 74.1% of all the pupae, with a further 19.0% found in miscellaneous small containers. The utility of the pupal/demographic-survey methodology in the evaluation of dengue risk in the study area, and other areas of Cuba with low densities of Ae. aegypti, is discussed.

[Biologic effect of diflubenzuron on Blattella germanica (Dictyoptera: Blattellidae)]. / Actividad biológica del diflubenzuron sobre Blattella germanica (Dictyoptera: Blattellidae).

The Amejeiras strain of Blatella germanica (Dictyoptera: Blattellidae) kept in lab conditions since 1994 and susceptible to arpocarb, malathion and cipermethrin insecticides, was studied. This strain was treated with 4 diflubenzuron (Dimilin OMS 1804) concentrations supplied by feeding nymphs at their first stage of development, with the purpose of determining their effect on the survival, phenotype and period of nynmphal development of this species. The dosage-mortality line of regression was determined and the values of CE50 = 0.042% and CE95 = 0.357% were obtained. Sublethal effects were observed in the nymphs treated with the 4 tested concentrations whereas the morphogenetic effects in adult insects only occurred when they were exposed to higher concentrations (0.25% and 0.4%). The nymph development stage showed a highly significant increase when the diflubenzuron concentration was raised. (F = 11.64; p < 0.001).

[Entomological surveillance over Aedes (S) aegypti and other culicids in Ciudad de La Habana, Cuba 1991-1996]. / Vigilancia entomológica de Aedes (S) aegypti y otros culícidos en Ciudad de La Habana, Cuba 1991-1996.

The results of the entomologic surveillance carried out from 1991 to 1996 in Boyeros municipality, City of Havana within the Program for Eradication of Aedes aegypti were analyzed. Data on mosquitoes fauna collected in the municipality by various sampling methods, larval survey, human bait, capture at rest and larval traps. Culex quinquefasciatus, Aedes mediovittatus and Aedes aegypti species were the most found by the different methods. It was proved that water tanks, man-made deposits, other kinds of tanks and low tanks were the most exploited resources by mosquitoes for their breeding in this municipality whereas larval surveys were the most sensitive method for detecting species since it contributed a greater variety of species. Reference is made to the search for a mechanism that help estimate adult populations from larval indices provided by surveys and the method of capture at rest is stressed as the most sensitive method for adult mosquitoes, particularly for dengue vector within the surveillance system aimed at this species.

[Typing habitats of Aedes albopictus in Cuba and their association with other species of Culicidae, 1995-1998]. / Tipificación de hábitats de Aedes albopictus en Cuba y su asociación con otras especies de culícidos, 1995-1998.

A typing of the habitats of Aedes albopictus in Cuba was made after its detection in 1995. It was observed in suburban areas of the Boyeros Municipality, in Havana City, where a study was conducted from October, 1995, to July, 1998. Most of the positive repositories were found outside the houses. Tins, tires, trees and plants were the places preferred for its breeding. It was found in the breeding places associated with Aedes mediovittatus and Culex quinquefasciatus, dominant species in these places. It was also observed a trend towards an increase of the number of repositories colonized only by the species under study. Reference was made to the phenomenon of competence between this species and the indigenous species present in such places.

[Incidence of Aedes (S) aegypti and other Culicidae in the municipality of Playa, La Habana City]. / Incidencia de Aedes (S) aegypti y otros culícidos en el municipio Playa, Ciudad de La Habana.

An analysis was made on the incidence of Culicidae present in Playa Municipality, Havana City, during the intensive stage of the anti-aegypti campaign from June to July, 1997, according to its requirements. Culex quinquefasciatus was the predominant species with a total of 269 focuses. It was collected in all the People's Councils and in every type of repository, excepting clay repositories. The second most abundant species was the Aedes aegypti with 199 focuses, followed by Aedes mediovittatus with 67. The Almendares-Sierra, Ampliación-Almendares and Miramar People's Councils showed the highest values of Culicidae infestation in the municipality. The Aedes aegypti prevailed in the first and Cx. quiquefasciatus in the second. The artificial repositories, low tanks and other repositories had the highest number of mosquito focuses in the municipality. The Cx quinquefasciatus preferred the artificial depositories, whereas the A. aegypti preferred the low tanks. Most of the positive depositories were colonized by only one species (92.7% of the total). 7.3% corresponded to mixed focuses. It was found that Cx. quinqufasciatus and A. aegypti were the most associated species.

[Ecologic indexes in the surveillance system of Aedes aegypti (Diptera: Culicidae) in Cuba]. / Indices ecológicos en el sistema de vigilancia de Aedes aegypti (Diptera: Culicidae) en Cuba.

The ecological indexes called diversity (H') and equitability (J') of the mosquito species were determined in six of the most common reservoirs of the urban ecosystem in the Plaza de la Revolución municipality, City of Havana. Data analysis showed that according to the values of these indexes, the most dangerous reservoirs were tyres, larvitraps and artificial reservoirs in general. Reference is also made on the use of larvitraps in the surveillance system of Aedes aegypti and the detection and stabilization of mosquitoes such as Aedes mediovittatus and Culex migripalpus in the urban ecosystem. The variety of species ranged from 2 to 7 in the studied reservoirs which showed differences in the patterns of use of the resources in the urban ecosystem.

[Proportional abundance of culicidae in the urban ecosystem of Havana City]. / Abundancia proporcional de culícidos en el ecosistema urbano de Ciudad de La Habana.

Proportional abundance of the four most common mosquito species was determined in six types of breeding places located in Plaza de la Revolución municipality, City of Havana from 1993-1996. Culex quinquifasciatus exhibited values over 0.60 except in tyres and larval traps in 1993 and 1994 whereas Aedes mediovittatus showed similar values in low tanks and artificial reservoirs in 1994 (0.43 and 0.56 respectively). It was also observed that this species prefers larval traps. Aedes aegypti and Culex migripaplpus had the lowest abundance values (0.01). These results allowed us to state that there is a sort of shared use by these species of those reservoirs where they breed and that Culex quinquefasciatus is the predominant one.

[The incidence of Culicidae in an urban area of Ciudad de La Habana during 1995]. / Incidencia de culícidos en una zona urbana de Ciudad de La Habana durante 1995.

In the present paper it is made an analysis of the incidence of culicides in the municipality of Marianao, Havana City, during 1995, after following the requirements of the National Program for the Eradication of Aedes aegypti. 6 species of mosquitoes were found in the municipality, with a predominance of the Culex quinquefasciatus and Aedes mediovittatus species. 4 focuses of Aedes aegypti were detected during this period. It was found that the groups of deposits preferred by the culicides for their breeding in this municipality were other deposits, low tanks, artificial deposits and larva traps. The People's Councils 4 and 5 (Libertad and Pogolotti) had the highest number of focuses (967 and 1,240, respectively, and therefore, they need more attention. It is analyzed the influence of the deficiencies of the public services, such as the collection of solid, wastes (garbage) and the existence of leakages and sewing overflows, on the proliferation of mosquitoes in the municipality.

[The effect of 2 diets on the biological aspects of Blattella germanica (Dictyoptera: Blattellidae) under laboratory conditions]. / Efecto de 2 dietas sobre aspectos biológicos de Blattella germanica (Dictyoptera: Blattellidae) en condiciones de laboratorio.

It was conducted a study of 2 colonies of Blattella germanica (Dictyoptera: Blattellidae) kept since 1994 in the laboratory at 29 +/- 1 degrees C, 70-75% of relative humidity and with different foods: one on a diet without proteins, consisting in portions of potatoes (Solanum tuberosum, L.), ripe banana (Musa paradisiaca, L.) and a sugary solution 10%, and the other with a protein content of 20.45% composed of pulverized and dry laboratory food for rats and a source of water. 6 nymphal stages were found with both types of food. There were determined the times of interchanges and the time of nymphal development, which were much shorter among the nymphs fed with proteins. The longevity of each sex showed no significant differences in connection with the type of food used. The times of appearance and eclosion of the oothecae of each oothecal cycle were determined with both foods. It was found that the females deposited up to 5 oothecae during their lives with the 2 types of diet. The average of nymphs per ootheca among the females fed with proteins was much greater (t = 5.33; p < 0.001). The results of this study show that when the food for B. germanica contains proteins, its nymphal development is faster and its reproductive capacity increases, which means that protein is a necessary nutrient for the diet of this species.

[Life tables of Blattella germanica (Dictyoptera: Blattellidae) under laboratory conditions and their importance for its control]. / Tablas de vida de Blattella germanica (Dictyoptera: Blattellidae) en condiciones de laboratorio y su importancia en el control.

A study of the life tables of Blatella germanica (L.) 1767 was conducted under laboratory conditions. 3 treatments were used a according to the number of individuals in each breeding flask (A = 9 flasks with 20-25 individuals, B = 17 flasks with 30-35 individuals, and C = 30 flasks with a newly hatched nymph each). The main parameters of the population growth were calculated by the TABVID software . The respective values for treatments A and B were the following: net reproduction rate (Ro 2.23 and 2.37), natural increase finite rate (lambda = 1.06), natural increase intrinsic rate (r = 0.06), and mean generational time (T = 13.89 and 15.64). The behaviour of the survival probability by age, the fertility rate, and the mortality rate were graphically registered. Life expectancy for treatment C was 16.47 and the survival rate for this treatment was represented by a graph. Graphics of the growth curve of this species and of the survival rate for treatments A and B were shown. The latter was concave, which means that mortality is higher during the young stages. This study provides esential cuantitative basic date that allow to carry out a more efficient control if fight is directed to the period where the highest natural mortality was found, that is, at the step from nymph 6 to adult in treatments A and B.

[Biological aspects of Blatella germanica (Dictyoptera: Blattellidae) in laboratory conditions]. / Observaciones sobre aspectos biológicos de Blattella germanica (Dictyoptera: Blattellidae) en condiciones de laboratorio.

In a study of Blatella germanica (L) 1767 (Dictyoptera: Blattellidae) carried out in laboratory conditions, 6 nymphal stages were found in a period of 114.71 days, at 29 +/- 1 degrees C and 80-90% of relative humidity. Times of appearence and eclosion of every ovipositted ootheca, as well as the offspring average of each one, were determined. Females ovipositted up to 5 oothecas during their life. The maximum average of eggs found per ootheca was 29.22. The average longevity of males was lower that that of females (77.23 and 98.40 days, respectively) (t = 2.21; p < 0.05).

Effects of three organophosphorus insecticides in the reproductive potential of Culex quinquefasciatus.

A Culex quinquefasciatus Say 1823 strain with resistant genes to organophosphates was tested in the laboratory to know the reproductive potential after exposure, as larvae, at the LC30 and LC70 (mg/l) of three organophosphorus insecticides: malathion, chlorpyrifos and methyl-pirimiphos. Data showed that fecundity was decreased significantly by malathion at LC30 = 0.0025 and LC70 = 0.0075, whereas fertility has a no significant decrement by chlorpyrifos and methyl-pirimiphos at the LC70 (0.000016, 0.00043). The sexual index was affected by chlorpyrifos and methyl-pirimiphos showing a greater number of adult females.

[Effect of cypermethrin on some reproductive factors in Culex (C) quinquefasciatus Say 1823]. / Efecto de la cipermetrina sobre algunos factores reproductivos en Culex (C) quinquefasciatus Say 1823.

An experiment was carried otu with a Culex quinquefasciatus strain with resistance genes called "Quibú", and with a susceptible strain provided by the WHO; they were pressured with different lethal doses of cypermetrine. Time-mortality regression lines of the 2 strains were estimated following WHO methodology and the "Quibú" strain showed tolerance to the insecticide. TL30 and TL70 were selected to test their effect on fecundity, fertility, sexual index, and egg eclosion time. A significant reduction in fecundity and fertility was observed in the "Quibú" strain after it was pressured, no effect was detected on the sexual index and egg eclosion time in this strain.

[Effect of 3 organophosphates on the reproduction of Culex quinquefasciatus Say 1823]. / Efecto de 3 organofosforados sobre la reproducción de Culex quinquefasciatus Say 1823.

An experiment was carried out with a Culex quinquefasciatus strain with resistance genes called "Quibú", this strain was pressured with 3 organophosphorous insecticides: malathion, chlorpyriphos, and pyrimiphos-methyl. The most toxic for this species was the chlorphyriphos (LC50 = 0.000009 mg/L), followed by pyrimiphos-methyl (LC50 = 0.00026 mg/L), and malathion (LC50 = 0.0035 mg/L). Larvae surviving the effects of the LC30 and LC70 of the three insecticides were selected to test their effect on fecundity, fertility and sexual index. Fecundity was not affected by the employed doses of chlorpyriphos and pyrimiphos-methyl, while a significant decrease was observed with the LC30 and LC70 of malathion. The employed doses of malathion did not affect fertility but there was a slight decrease with the LC70 selections of chlorpyriphos and pyrimiphos-methyl. The proportion of adult females showed a significant increase with the doses of chlorpyriphos and pyrimiphos-methyl; sexual index was not affected by malathion.

Presence of Aedes (Gymnometopa) mediovittatus in Cuba: a new factor to be considered in the national campaign to eradicate dengue.

To assess the presence of the potential dengue vector Aedes mediovittatus relative to other mosquito species, data were examined from 44,199 larvitraps operating between January 1984 and December 1987 in the town of Mariel, Cuba. Of 1,068 larvitraps containing mosquitoes, 626 (58.6%) were positive for Ae. mediovittatus. Its relative presence increased each year except 1986, going from 37.9% of the positive traps in 1984 to 70.2% in 1987. More larvitraps were positive for Ae. mediovittatus than for Culex quinquefasciatus, which typically dominated breeding sites at the end of the intensive phase of the national campaign against Ae. aegypti in the early 1980s. The results appear to reflect Ae. mediovittatus' gradual infiltration into areas covered by the campaign, a factor that may need to be considered in efforts to control dengue in the Americas.

[Comparison of 3 methods for collecting adult anophelines in a risk area of malaria transmission]. / Comparación de 3 métodos de captura de anofelinos adultos en una zona con riesgo de transmisión palúdica.

Three methods of collecting adult anophelines were comparatively studied in a rural town in Havana Province, during the period comprised between June and September 1986. The methods of capture used were as follows: in resting sites, in human bait and through lactic acid CDC light traps. A greater number of anophelines (F = 6.86; p less than 0.01) was collected on human bait. The capture of 11 species of culicines was reported.