Changes in the sexual dimorphism of triatominae in the transition from natural to artificial habitats

A shift from large to small average sizes was observed in Triatoma infestan s and Rhodnius domesticus between field and domestic (or laboratory) condit ions of life. It was more pronounced in the female specimens, leading to a subsequent reduction of sexual size dimorphism. This feature is discussed i n terms of genetic and populational changes occurring from natural to artif icial habitats, in particular those related to population densities. Sexual size dimorphism is then recommended as a new character to be used in the s tudy of species of Triatominae adapting to domestic ecotopes.