Feeding and defaecation behaviour of Triatoma patagonica (Del Ponte, 1929) (Hemiptera: Reduviidae)

Abstract

Among the vectors of Chagas disease, (Carcavallo et al. 1999).It was found naturally infected by Trypanosoma cruzi (Chagas 1909) (Lent & Wygodzinsky 1979) and in Río Colorado (province of Río Negro) it was the only peridomestic species found in houses both in urban and suburban areas (Ferrero et al. 1999). These last records, added to the permanence in the peridomicile, point the need to determine how competent T. patagonica is as a vector of Chagas disease, especially in aspects related to feeding and defaecation.These two processes (feeding and defaecation) have been thoroughly analyzed in triatomines as they are closely related to the development and transmission of T. cruzi (Mello 1980, Kirk & Schofield 1987, Trumper & Gorla 1991, Crocco & Catalá 1996. These processes are well known in domestic species like T. infestans (Klug, 1934) (Forattini et al. 1982, Friend & Smith 1985, Trumper & Gorla 1991 and Rhodnius prolixus (Stal, 1859) (Forattini et al. 1982, Friend & Smith 1985. Nevertheless, very little is known about peridomestic species including T. patagonica (Del Ponte, 1929) about which only facts relating to its life cycle and habitats are known (Martínez et al. 1985, Carcavallo et al. 1998.From an epidemiological point of view, it is very important to have knowledge related to feeding and defaecation, the aim of this work is to evaluate the feeding pattern and the defaecation behaviour in adults of T. patagonica. MATERIALS AND METHODSThis work was carried out with 29 adult females of T. patagonica. These were obtained as fifth instar nymphs by the Servicio Nacional de Chagas (Argentina). The insects were maintained under laboratory conditions at 26ºC ± 1ºC and at 60-70% humidity. After moulting, the insects were weighed and marked with acryllic paint following predetermined codes and were starved for 15 days (after moulting). After fasting, they were fed ad libitum on a restrained pigeon. For each feeding the following variables were determinated:Blood meal size -This was determined by the difference in weight before and after feeding.Feeding time -This was obtained by recording the time (in minutes) since the rostrum of the insect came into contact with the skin of the host until it detached itself.Number of defaecations during feeding -This was registered by direct observation of the insect while feeding on the pigeon.Number of defaecations emitted during the first 30 min after feeding -This was registered by direct observation of the insect while it was on the host and during 30 min after feeding.All weights were measured using a Mettler Balance with a precision of 0.001 mg. The t-test for samples with dependent variables for comparing variables of the different groups, was used as statistic treatment. To verify the homogeneity of variance the Levenne test was used (Ferrán Aranaz 2001). RESULTSIn Table I, the variables analyzed concerning feeding behaviour of females of T. patagonica are shown. The data were obtained from the repletion feeding of 29 females of T. patagonica, the average time rec...

Ecological characteristics of Triatoma patagonica at the Southern limit of its distribution (Chubut, Argentina)

“…In addition, this species seems to be capable of transmitting T. cruzi because it defaecates while feeding on the host (Nattero et al 2002). However, in agreement with data of Bejarano et al (1967) and Virla de Arguello (1984) for the Province of Chubut, the specimens of T. patagonica collected in our survey were all uninfected, which may reflect their predominant association with chickens which are refractory to T. cruzi infection.…”

Dynamics of feeding and defecation in Triatoma vitticeps (Stal, 1859) (Hemiptera, Reduviidae, Triatominae) and its potential in the transmission of Trypanosoma cruzi

“…When the amount of blood ingested is large, triatomines eliminate their faeces more rapidly due to the high water content of blood (Friend & Smith 1985). Nattero et al (2002) also observed a correlation between the volume of blood ingested and the time to defecation, confirming that females are potentially more efficient in infecting vertebrates with T. cruzi.…”

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

“…However, when the amount of ingested blood was assessed, T. williami obtained higher or very close volumes in relation to those of the last three species and also to others considered as excellent vectors, as T. sordida and T. patagonia (Guarneri et al, 2000b;Nattero et al, 2002). If the WG is unfavorable to the vectorial capacity of T. williami, the opposite is given by the amount of ingested blood.…”