Variations in time and space of an Andean wild population of T. infestans at a microgeographic scale

Abstract

BackgroundWild populations of Triatoma infestans are now believed to be the source of reinfestation of dwellings in some Andean areas and could impede the full achievement of vector control campaigns in this region. Given the poor knowledge of these populations in natural conditions, their basic biology traits, such as monthly demographic variations and movements of individuals, were explored.MethodsA previously identified wild population of T. infestans in a field adjacent to a group of isolated houses in an Andean valley (department of La Paz, Bolivia) was explored using regular capture assays over 13 months in 50 sites selected at the beginning of the study. The capture-mark-recapture method was applied monthly using mouse-baited adhesive traps for captures and fingernail polish of different colors for the marking.ResultsThe monthly capture assays did not show significant differences between rainy and dry seasons, showing evidence for a certain stability of the wild T. infestans population with only the nymph population tending to decline during the middle of the rainy season when rain is more intensive. Throughout the study, the monthly average number of bugs was 51.1 ± 25.3 per assay, 91.1% were nymphs, and they were found at 30 of the 50 sites (60%). The number of times a site was positive varied from one to 13. Site infestation was associated with the underground position of the traps, and rocks around and in the surroundings of the traps. The recaptures after marking were successful (138 recaptures over the study). The marking made it possible to detect for 14.5% of the recaptures significant movements of adults (up to 168 m) and nymphs (up to 34 m). Some bugs (nymphs and females) were recaptured after 5 months. For adults, recaptures (46 in total) mostly occurred between September and March. Females were recaptured twice as frequently as males.ConclusionThe Andean wild populations of T. infestans showed a strong spatial and temporal stability during the year-long study. Dispersal may occur mainly during the rainy season. The capture-mark-recapture method was successful and the longevity of the bugs and the distances covered by nymphs and adults were recorded.

Morphometric Wings Similarity among Sylvatic and Domestic Populations of Triatoma infestans (Hemiptera: Reduviidae) from the Gran Chaco Region of Paraguay

“… 14 To support this new paradigm, recent genetic studies in the Andes showed that first-generation migrants within different populations have provided evidences of insect movement from the sylvatic to the intra- and peridomestic areas, enhancing the hypothesis of vector transmission risk from the invasion of human habitats by sylvatic populations of T. infestans . 15 , 16 These data show the relevance of sylvatic T. infestans populations in their possible role in the recolonization of treated areas and potential exchange between sylvatic and intraperidomestic triatomine populations in a wide geographical area of Grand Chaco under epidemiological risk of transmission of Trypanosoma cruzi.…”

Prevalence, infected density or individual probability of infection? Assessing vector infection risk in the wild transmission of Chagas disease

“…New studies may improve this caveat by including more accurate measurements of vector and hosts' home ranges, or distance-dependent space use probabilities instead of fixed areas. In addition, it has not been determined in the field if all developmental stages of M. spinolai move the same distances or with the same frequency, and triatomine nymphs are expected to be movement restricted when compared to adults [52]. This fact could affect the probability of stage-specific vector-host contact.…”

Potential impact of climate change on the geographical distribution of two wild vectors of Chagas disease in Chile: Mepraia spinolai and Mepraia gajardoi

“…Based on the hypothesis of accessible areas by dispersal over relevant time periods (M, hereafter) for both Mepraia species [15, 45], we set 2° (~222 km) buffer areas around each occurrence. The genus Mepraia is a dispersal restricted group, given that most developmental stages disperse by walking, unlike winged males that can also fly [4, 43, 46]; therefore, the accessible areas used were conservative compared to previous reports [e.g. 35, 37].…”