Modification of the Daily Activity Pattern of the Diurnal Triatomine Mepraia spinolai (Hemiptera: Reduviidae) Induced by Trypanosoma cruzi (Trypanosomatida: Trypanosomatidae) Infection (original) (raw)
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Trypanosoma cruzi Parasite Load Modulates the Circadian Activity Pattern of Triatoma infestans
Insects
American trypanosomiasis is a disease caused by the flagellate protozoan Trypanosoma cruzi, which is transmitted mainly in endemic areas by blood-sucking triatomine vectors. Triatoma infestans is the most important vector in the southern cone of South America, exhibiting a nocturnal host-seeking behavior. It has been previously documented that the parasite produces changes in some triatomine species, but this is the first time that the behavior of a vector has been evaluated in relation to its parasite load. After comparing the movement events and distance traveled of infected and non-infected T. infestans, we evaluated the change produced by different T. cruzi parasite loads on its circadian locomotor activity. We observed differences between infected and non-infected triatomines, and a significant relation between the parasite load and the increase in locomotor activity of T. infestans, which was accentuated during the photophase. This could have direct implications on the transmi...
Microorganisms
Trypanosoma cruzi is the causal agent of Chagas disease, a parasitic zoonosis transmitted mainly through the feces of triatomine insects. Triatoma infestans is the main triatomine vector of this disease in South America. Previous research has shown that T. cruzi infection modifies the behavior of triatomines. We evaluated, for the first time, the effect of parasite load on feeding and defecation behavior, which we quantified by using real-time PCR. The detection time of the host was shorter in infected individuals, and the number of bites increased, while the dejection time was reduced when compared with the non-infected group. A significant correlation between the parasite load and the behavioral changes registered in the infected triatomines was found. These results would indicate that the intensity of T. cruzi infection modulates the feeding and defecation behavior of T. infestans, increasing the vector competence of this triatomine vector.
Memorias Do Instituto Oswaldo Cruz, 2006
Adults of Triatoma vitticeps infected by flagellates similar to Trypanosoma cruzi are frequently captured by the inhabitants of rural areas in the Brazilian state of Espírito Santo. The dynamics of feeding and defecation were observed in three groups of adult triatomines, consisting of sylvatic T. vitticeps and laboratory-reared specimens of this species and T. infestans. Triatomines were observed from the moment they were presented with an immobilized chicken as a bloodmeal source until 240 min after feeding had ended. Mean times between the end of feeding and defecation for T. infestans, wild T. vitticeps and laboratory-reared specimens of the latter species were 1.2, 21.1, and 64 min respectively. All T. infestans defecated within 10 min of feeding, while only 29.9 of wild and 52.8% laboratory-reared specimens of T. vitticeps did so within this period. These results may explain the low efficiency of T. vitticeps in T. cruzi transmission to man. The shorter time between feeding and defecation in laboratory-reared T. vitticeps may indicate a change in behaviour of this species as a result of adaptation to an artificial environment.
Circadian entrainment by light and host in the Chagas disease vector, Triatoma infestans
Chronobiology International, 2014
Triatoma infestans (Reduviidae: Triatominae, ''kissing bug'') is the main insect vector of Trypanosoma cruzi, the causative agent of Chagas disease, a chronic trypanosomiasis infecting 10 million people world-wide. This hematophagous bug feeds on diurnal and nocturnal species during each host's quiescent time. As the hosts are also its major predators, kissing bugs are subjected to dual selective pressures from a single source. Therefore, synchronization of feeding with the host's behavior is critical to the insects' survival. We show that nonphotic signals linked to the host eclipse the role of light and dark as the primary circadian zeitgeber for these bugs, although light still strongly inhibits locomotor behavior directly. In nature, this combination provides the insect with great flexibility in organizing physiology and behavior: anticipating a quiescent host or avoiding its potential predation while remaining directly responsive to immediate environmental conditions. Manipulation of nonphotic entrainment could be a useful chronobiotic tool in the control of Chagas disease.
Background As a result of evolution, the biology of triatomines must have been significantly adapted to accommodate trypanosome infection in a complex network of vector-vertebrate-parasite interactions. Arthropod-borne parasites have probably developed mechanisms, largely still unknown, to exploit the vector-vertebrate host interactions to ensure their transmission to suitable hosts. Triatomines exhibit a strong negative phototaxis and nocturnal activity, believed to be important for insect survival against its predators. Methodology/Principal Findings In this study we quantified phototaxis and locomotion in starved fifth instar nymphs of Rhod- nius prolixus infected with Trypanosoma cruzi or Trypanosoma rangeli. T. cruzi infection did not alter insect phototaxis, but induced an overall 20% decrease in the number of bug loco- motory events. Furthermore, the significant differences induced by this parasite were con- centrated at the beginning of the scotophase. Conversely, T. rangeli modified both behaviors, as it significantly decreased bug negative phototaxis, while it induced a 23% increase in the number of locomotory events in infected bugs. In this case, the significant effects were observed during the photophase. We also investigated the expression of Rpfor, the triatomine ortholog of the foraging gene known to modulate locomotion in other insects, and found a 4.8 fold increase for T. rangeli infected insects. Conclusions/Significance We demonstrated for the first time that trypanosome infection modulates the locomotory activity of the invertebrate host. T. rangeli infection seems to be more broadly effective, as besides affecting the intensity of locomotion this parasite also diminished negative photo- taxis and the expression of a behavior-associated gene in the triatomine vector.
Sleeping habits affect access to host by Chagas disease vector Triatoma dimidiata
Parasites & Vectors, 2016
Background: Chagas disease, caused by the parasite Trypanosoma cruzi, is mainly transmitted by blood-sucking bugs called triatomines. In the Yucatán Peninsula, Mexico, the main vector of T. cruzi is Triatoma dimidiata. While this species may colonize houses in other regions, it is mostly intrusive in Yucatán: it generally lives in sylvan and peridomestic areas, and frequently enters inside homes, likely attracted by potential vertebrate hosts, without establishing colonies. Bugs collected inside homes have a low nutritional status, suggesting that they cannot efficiently feed inside these houses. We hypothesized that this low nutritional status and limited colonization may be associated, at least in part, with the local practice in Mayan communities to sleep in hammocks instead of beds, as this sleeping habit could be an obstacle for triatomines to easily reach human hosts, particularly for nymphal instars which are unable to fly. Methods: We used an experimental chamber in which we placed a miniature bed in one side and a miniature hammock on the other side. After placing a mouse enclosed in a small cage on the bed and another one in the hammock as baits, T. dimidiata bugs were released in the chamber and their activity was video recorded during the night. Results: T. dimidiata adults and nymphs were able to reach the mouse in bed significantly more often than the mouse in hammock (Binomial test, P < 0.0001). Moreover, females reached the mice twice as often as did males. Most of the adult bugs reached the mouse in bed by walking, while they reached the mouse in hammock by flying. Nymphs presented a host-seeking index ten times lower than adult bugs and were also able, on a few occasions (4/132 released bugs), to reach the mouse in hammock. Conclusions: We conclude that sleeping in hammocks, as done in rural Yucatán, makes human hosts less accessible to the bugs. This, combined with other factors (e.g. absence of domestic animals sleeping inside houses), may explain, at least in part, the low nutritional status of bugs collected inside homes and the limited colonization of houses by T. dimidiata in the region. Nevertheless, while this sleeping habit limits contact with the bugs, it does not confer complete protection as adult bugs as well as some nymphs were still able to reach the host in hammock in our study.
PLOS Neglected Tropical Diseases
Background Several studies addressed changes on the insect vector behavior due to parasite infection, but little is known for triatomine bugs, vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. We assessed infection rates and metacyclogenesis of T. cruzi (TcVI) in fifth-instar nymphs of Triatoma rubrovaria comparing with the primary vector Triatoma infestans. Also, biological parameters related to feeding-excretion behavior were evaluated aiming to identify which variables are most influenced by T. cruzi infection. Methodology/principal findings Fifth-instar nymphs of T. rubrovaria and T. infestans were fed on mice infected with T. cruzi (TcVI). We compared the presence and the number of parasite evolutive forms in excreta of both triatomine species at 30, 60 and 90 days post-infection (dpi) with traditional statistical analyses. Moreover, both species were analyzed through generalized linear models and multinomial logistic regression hypotheses for seven behavioral parameters related to hostseeking and feeding-excretion. Triatoma rubrovaria and T. infestans had similar overall infection and metacyclogenesis rates of T. cruzi TcVI in laboratory conditions. Regarding vector behavior, we confirmed that the triatomine's tendency is to move away from the bite region after a blood meal, probably to avoid being noticed by the vertebrate host. Interspecific differences were observed on the volume of blood ingested and on the proportion of individuals that excreted after the blood meal, revealing the higher feeding efficiency and dejection rates of T. infestans. The amount of ingested blood and the bite behavior of T.
Chagas disease parasite induces behavioural changes in the kissing bug Mepraia spinolai
Acta Tropica, 2006
Parasites have been shown to manipulate the feeding behaviour of their invertebrate vectors, which results in an increased probability of transmission to definitive hosts. Most evidence for this hypothesis comes from protozoan species with salivary transmission but evidence for stercorarian parasite transmission is lacking. We present experimental evidence that infection of the kissing bug Mepraia spinolai (Hemiptera; Reduviidae) with the protozoan Trypanosoma cruzi reduced the time to detect potential hosts in comparison to control insects. Infected bugs bit about twice more often than uninfected nymphs and defecated 8 min after the last blood meal whereas uninfected bugs needed 11 min. The behaviour of male and female nymphs did not differ significantly. Since all of these traits relate to parasite transmission, we suggest that parasite-mediated changes in the foraging and defecation behaviour of M. spinolai may promote the spread of T. cruzi toward definitive hosts.
Chagas disease parasite induces behavioural changes in the kissing bug< i> Mepraia spinolai
Acta tropica, 2006
Parasites have been shown to manipulate the feeding behaviour of their invertebrate vectors, which results in an increased probability of transmission to definitive hosts. Most evidence for this hypothesis comes from protozoan species with salivary transmission but evidence for stercorarian parasite transmission is lacking. We present experimental evidence that infection of the kissing bug Mepraia spinolai (Hemiptera; Reduviidae) with the protozoan Trypanosoma cruzi reduced the time to detect potential hosts in comparison to control insects. Infected bugs bit about twice more often than uninfected nymphs and defecated 8 min after the last blood meal whereas uninfected bugs needed 11 min. The behaviour of male and female nymphs did not differ significantly. Since all of these traits relate to parasite transmission, we suggest that parasite-mediated changes in the foraging and defecation behaviour of M. spinolai may promote the spread of T. cruzi toward definitive hosts.