All members of Triatominae subfamily (Heteroptera: Reduviidae), potential vectors of Trypanosoma cruzi, etiologic agent of the Chagas disease, feed on blood. Through evolution, these bugs have fixed special morphological, physiological, and behavioral aptations (adaptations and exaptations) adequate to feed on blood. Phylogeny suggests that triatomines evolved from predator reduvids which in turn descended from phytophagous hemipterans. Some pleisiomorphic traits developed by the reduvid ancestors of the triatomines facilitated and modeled hematophagy in these insects. Among them, mouthparts, saliva composition, enzymes, and digestive symbionts are the most noticeable. However, the decisive step that allowed the shift from predation to hematophagy was a change of behavior. The association of a predator reduvid with nesting vertebrate (≈110 to 32 Ma) permitted the shift from an arthropod prey to a vertebrate host. In this work, we review the phylogeny and dispersion of triatomines and the current controversy over the monophyly or polyphyly of this group. We also discuss how these insects were able to overcome, and even have taken advantage of, diverse ancestral and physical barriers to adapt to sucking blood of nidicolous vertebrates. We provide a Spanish version of this work.

In xeric ecosystems, ant diversity response to aridity varies with rainfall magnitude and gradient extension. At a local scale and with low precipitation regimes, increased aridity leads to a reduction of species richness and an increased relative abundance for some ant species. In order to test this pattern in tropical environments, ant richness and relative abundance variation were evaluated along 35 km of an aridity gradient in the Araya Peninsula, state of Sucre, Venezuela. Three sampling stations comprising five transects each were set up. Pitfall traps and direct collecting from vegetation were assessed per transect. Overall, 52 species, 23 genera, and 7 subfamilies of ants were recorded in the peninsula. The total number of species and genera recorded by both sampling stations and transects decreased linearly with increasing aridity. Total relative abundance was highest in the most arid portion of the peninsula, with Crematogaster rochai (Forel) and Camponotus conspicuus zonatus (Emery) (Hymenoptera: Formicidae) being the numerically dominant species. Spatial and multivariate analyses revealed significant changes in ant composition every 11 km of distance, and showed a decrease of ant diversity with the increase of harsh conditions in the gradient. Here, we discuss how local geographic and topographic features of Araya originate the aridity gradient and so affect the microhabitat conditions for the ant fauna.Electronic supplementary materialThe online version of this article (doi:10.1007/s13744-012-0096-y) contains supplementary material, which is available to authorized users.

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There are incomplete data about ant taxonomy and diversity in the Caribbean islands of Venezuela. In order to broaden myrmecological information in the Peri-Caribbean arid belt, ground-dwelling ant assemblage of the Macanao semi-arid peninsula (Margarita Island) was sampled with a Rapid Assessment Program (RAP). Two study sites on the northern slope of the peninsula were chosen, La Chica (LC) at 70 m of altitude and Cerro Macanao (CM) at 598 m of altitude. Sixty pitfall traps (30 per site) and 96 man-hours of manual collecting (48 man-hours per site) were employed. Overall, 40 species and 32 genera from eight subfamilies were recorded, twice the number of species previously reported for Margarita Island. Differences in ant species richness and structure were detected between both sites, with 31 species in CM and 25 species in LC. Such variations indicate that microclimatic conditions are more favorable in uplands than lowlands in Macanao. This situation may be attributed to the moisture gradient effect upon vegetation, and microclimatic conditions influenced by peninsular orography. Our findings corroborate that the pattern of higher diversity with higher altitude in arid zones also holds for the tropics, and suggest a continental origin for the Lesser Antilles ant fauna.