Vital Statistics of Panstrongylus geniculatus (Latreille 1811) (Hemiptera: Reduviidae) under Experimental Conditions

Abstract

A statistical evaluation of the population dynamics of Panstrongylus geniculatus is based on a cohort experiment conducted under controlled laboratory conditions. Animals were fed on hen every 15 days. Egg incubation took 21 days; mean duration of 1st, 2nd, 3rd, 4th, and 5th instar nymphs was 25, 30, 58, 62, and 67 days, respectively; mean Panstrongylus geniculatus (Latreille 1811), is widely distributed in America; it is found from southern Mexico to northern Argentina. It has epidemiological importance since it has been found naturally infected with Trypanosoma cruzi from the beginning of this century (Chagas 1912).In Venezuela, it has been captured in many states (Ramírez Pérez 1987). Pifano (1986) studying the urban Chagas' disease in the valley of Caracas reported individuals of P. geniculatus in human dwellings, apparently associated to the marsupial Didelphis marsupialis.It is attracted by light and has been collected in human dwellings, but it does not colonize them (Miles et al. 1981); it is a sylvatic species (Lent & Wygodzinsky 1979, Zeledón 1983.It has been little studied because of the difficulties for rearing and maintenance, and for the low number of collected specimens (Miles et al. 1981, Ramírez Pérez 1987; therefore, very little literature has been published on its biology, ecology and epidemiology. Barreto (1967) studied some ecological aspects and indicated a close association with some mammals like armadillo. Lent and Jurberg (1969) Here we present the results of a study of P. geniculatus fed only on hen, under controlled constant environmental conditions, with special emphasis on its demographic characteristics, in order to contribute to the kwowledge of the population dynamics of this species. MATERIALS AND METHODSThe population of P. geniculatus used in this experiment was obtained from a colony founded by a single female collected in a human dwelling in the area of San Jacinto, located in the city of Trujillo, Trujillo State, Venezuela. The colony was kept in a climatic chamber at 26±3°C and 90±10% RH, and fed on hens.Vital statistics described in this study were based on a cohort constituted by 63 recently laid eggs (0 to 48 hr old); these were kept in 150 cm 3 glass containers until all viable eggs hatched; then, all 1st instar nymphs were transferred to a 3,785 l broad mouth jar, covered with nylon mesh and provided with vertically placed strips of paper in order to allow insects to climb to the jar top at feeding time and provide them resting places and serve as laying sites.

Demographic fitness of Belminus ferroae (Hemiptera: Triatominae) on three different hosts under laboratory conditions

“…Hatching rates as low as those observed in B. ferroae fed on mice (16%) here have never been reported in Triatominae when fed on their natural vertebrate hosts (55-100%) (Feliciangeli & Rabinovich 1985, Cabello & Galíndez 1998, Guarneri et al 2000, Martínez-Ibarra et al 2003, 2007, Aldana & Lizano 2004, Arévalo et al 2007). The V x involves reproduction, survival and survival per age and it is difficult to establish which of these life history traits provides the dominant contribution to V x.…”

“…These three life history traits observed in various triatomine species (Feliciangeli & Rabinovich 1985, Cabello et al 1987, da Silva & da Silva 1989, Cabello & Galíndez 1998) correspond to those described by Heppell et al (2000) for long-lived species that mature late and have few offspring, where fecundity and early offspring survival are less critical than pre-adult survival to maturity [a "slow" strategy observed along several taxa, such as the "slow" mammals described by Read and Harvey (1989)]. The long development time and longevity, as well as the relatively low fecundity of B. ferroae , could represent an adaptive strategy for environments that are relatively "crowded" or display low food availability where selection favours efficiency of the conversion of food into offspring and minimises waste (Rabinovich 1974).…”

Investigación de vectores y reservorios en brote de Chagas agudo por posible transmisión oral en Aguachica, Cesar, Colombia

“…En cuanto a P. geniculatus con amplia distribución geográfica en Latinoamérica, está asociada a nidos de aves y madrigueras de mamíferos en hábitat silvestres, generalmente de hábitos terrestres y subterráneos, puede ser encontrada eventualmente en el intradomicilio y peridomicilio, por lo que es considerado un vector de T. cruzi de importancia secundaria 29 . Por otro lado, por su baja tasa de crecimiento natural, baja tasa neta de reproducción, largo tiempo generacional y baja productividad reproductiva se considera poco probable que se convierta en una especie domiciliada de importancia significativa 48 , sin embargo, recientemente se ha incriminado como transmisor de T. cruzi en Mérida (Venezuela), estado no endémico para la patología chagásica 49 ; se ha encontrado en zonas urbanas de Caracas 50 y colonizando viviendas rurales al noreste de Antioquia 51 . En el área de estudio podría ser el otro vector que se alimente sobre D. marsupialis y aunque sus poblaciones suelen tener bajas densidades presentan a menudo altos índices de infección con T. cruzi y al incursionar en la vivienda compiten con otros vectores por la alimentación sanguí-nea 52 y existe la posibilidad de que produzca contaminación de los alimentos 53 .…”

Life cycle and vectorial competence of Triatoma williami (Galvão, Souza e Lima, 1965) under the influence of different blood meal sources

“…Conversely, the nymphal development time of T. williami obtained in this study was much longer than that observed in species recognised as effective vectors exposed to birds and mammals as blood meal sources (Guarneri et al, 2000b). The biological cycle time represents the actual mean length of a generation time in terms of population dynamics (Cabello & Galíndez, 1998), and therefore, it may suggest inability of T. williami to build up significant populations due to the fact that this insect completes only one generation per year. Species with faster cycles, as T. infestans, forms large populations in domestic and peridomestic environments, where it generally completes two generations per year (Noireau et al, 2000;Schofield, 1985).…”