Kissing bugs spread across the Americas in three great waves tied to ancient climate shifts

Kissing bugs, the blood-feeding insects that transmit the parasite responsible for Chagas disease, did not spread across the Americas by chance. A new macroevolutionary reconstruction published in Frontiers of Biogeography shows that their lineage dispersals unfolded in three distinct phases over the past 60 million years, with the timing and direction of movement closely tracking swings in global paleotemperature. The study offers the first comprehensive overview of the routes taken by Triatominae lineages as they colonized the New World, from early outflows out of Amazonia to complex bidirectional exchanges that stitched together Mesoamerica, the Nearctic, and the South American dry diagonal.

The research team, led by biogeographers working with a time-calibrated phylogeny built from more than 2,500 ultraconserved elements and calibrated with Dominican amber fossils, estimated that the most recent common ancestor of the main kissing bug tribes arose around 59.2 million years ago. That date is older than many previous estimates, which had placed the origin of the subfamily between 45 and 30 million years ago, and it suggests that the initial diversification of Triatominae began significantly earlier than previously recognized, potentially preceding the major Andean uplift that reshaped the South American landscape.

To reconstruct where the group came from, the researchers fitted a dispersal-extinction-cladogenesis model to a presence-absence matrix of 96 species mapped across 11 bioregions derived from a network-based regionalization of the Americas. The model indicated that the ancestral range of the entire clade encompassed multiple areas, with northern South America and parts of Mesoamerica emerging as the most likely, albeit with small probability. This pattern points to a widespread or complex ancestral distribution rather than a single narrowly defined point of origin, though the classical hypothesis that the group arose in Central or northern South America remains the most plausible.

The team then simulated dispersal histories using 100 biogeographic stochastic mappings, generating 6,591 dispersal events whose timing could be compared across replicates. Because the number of branches in a phylogeny increases toward the present, raw event counts naturally rise as more lineages become available to disperse. To correct for this inherent bias, the researchers normalized dispersal frequency by the number of lineages through time, revealing a pattern that raw counts had obscured: a pronounced decline from roughly 60 to 35 million years ago, followed by a gradual recuperation toward the present.

A threshold regression model identified two significant breakpoints at 50 and 30 million years ago, delineating three phases with distinct linear trends. Phase A, spanning 60 to 50 million years ago, showed high normalized dispersal, with lineages moving from the Amazonian region toward northern South America and from northern South America into Mesoamerica, as well as from the Caatinga toward the Cerrado. Phase B, from 50 to 30 million years ago, exhibited a substantial decline and stabilization in dispersal activity, with movements concentrated among Mesoamerica and northern South America and routes reaching the Páramos, Caatinga, and Chaco. Phase C, from 30 million years ago to the present, marked a resurgence in dispersal with the most complex and frequent patterns of the entire reconstruction.

The association between these phases and climate is striking. Phase A coincided with the Paleocene-Eocene transition, a period of significant global warming that included the Paleocene-Eocene Thermal Maximum, and the higher dispersal rate during this interval may have been facilitated by warmer conditions that expanded habitat connectivity and suitability, particularly from tropical source regions like Amazonia. Phase B aligned with global cooling and the transition into the Oligocene, when temperatures dropped sharply. The researchers note that previous analyses of global plant range shifts revealed an approximately 30 percent decrease in movements into the world’s tropics during the Early Eocene Climatic Optimum around 52 million years ago, suggesting large-scale vegetational changes that could have influenced dispersal dynamics. Cooler temperatures might have reduced habitat suitability, increased environmental filtering, or restricted connectivity between regions, thereby limiting dispersal success for the kissing bug lineages.

Phase C encompasses the Miocene, Pliocene, and Pleistocene, a period of fluctuating but generally recovering temperatures compared to the Oligocene minimum, leading into the Quaternary glacial cycles. During this phase, a high frequency of bidirectional dispersals was observed between Mesoamerica and the Nearctic region, likely facilitated by the formation and stabilization of the Isthmus of Panama. Routes from Amazonia extended toward the Páramos and the Caatinga, indicating the continued influence of Amazonia as a source or transit area. Within the Atlantic biomes, a dynamic and reciprocal exchange between the Caatinga and the Atlantic Forest was evident, and dispersal routes following the South American dry diagonal, from Caatinga through Cerrado, Chaco, and Pampas, highlight the importance of drier biomes as corridors for movement. Routes from the Pampas toward both the Atlantic Forest and the Amazon Forest suggest more recent expansions into these areas.

A non-parametric statistical comparison of surface paleotemperatures grouped by dispersal phase revealed significant differences among all three phases, supporting the exploratory association between climate fluctuations and Triatominae dispersal dynamics. The researchers caution that this comparison is exploratory, but the alignment of the biphasic dispersal pattern with major paleotemperature shifts implies a potential influence of climatic change on the evolutionary dispersal processes of this medically important insect group. Individual routes also showed varying temporal peaks, with the bidirectional exchange between Mesoamerica and the Nearctic displaying distinct modes of activity, one peaking around 13 to 15 million years ago and another more recent.

The findings carry epidemiological weight because nearly all Triatominae species serve as vectors for Trypanosoma cruzi, the protozoan that causes Chagas disease, and understanding the historical processes that shaped their distribution may inform how these vectors respond to future environmental change. The study drew on a robust dataset of 18,438 unique occurrence records from the DataTri database, and the regionalization revealed that 54 percent of species were restricted to a single bioregion, underscoring how strongly dispersal history continues to define contemporary patterns of kissing bug diversity across the Americas. By quantifying the timing and directionality of lineage dispersals, the researchers have provided a macroevolutionary framework that connects deep-time biogeography with the present-day geography of one of the most consequential insect vectors in the Neotropics.

Subject of Research: Historical biogeography and dispersal timing of Triatominae (kissing bugs) across the Neotropics

Article Title: Timing and directionality of Triatominae ( Hemiptera , Reduviidae ) lineage dispersals in the Neotropics

Article References: Cardozo, M. D. L. B., Rabinovich, J. E., Lepeco, A., & Löwenberg-Neto, P. (2025). Timing and directionality of Triatominae (Hemiptera, Reduviidae) lineage dispersals in the Neotropics. Frontiers of Biogeography, 18, Article e132274. https://doi.org/10.21425/fob.18.132274

Image Credits: AI Generated

DOI: 10.21425/fob.18.132274

Keywords: Timing, directionality, Triatominae, Hemiptera, Reduviidae, lineage, dispersals, Neotropics, scientific research