On the genus Panstrongylus Berg 1879: evolution, ecology and epidemiological significance

Abstract

The genus Panstrongylus is currently composed of 13 species, several of which are involved in the transmission of Trypanosoma cruzi to humans in South and Central America. Some species exhibit minor morphological differences possibly associated with adaptation to different silvatic ecotopes or domestic environments. We present a distillation of past and recent literature pertaining to the biology of this group. In particular, we summarise the current status of the genus according to systematic and recent phylogenetic studies. In light of recent evidence suggesting polyphyly/paraphyly of the genus we have investigated the possible mechanisms of morphological convergence/divergence. By assessing postembryonic ontogeny we reveal that the distinctive head shape of Panstrongylus can be derived from a Triatoma-like head late in development. A comprehensive phylogenetic study is therefore required to elucidate their relationship with Triatoma spp., and other genera of the tribe Triatomini. We also present a comparative summary of biology, ecology and epidemiological significance for each species in the genus. This reveals that knowledge of many species is fragmentary or lacking. This is mainly due to the fact that, except for few species with synanthropic traits (P. megistus and P. lignarius [formerly P. herreri]), important vectors of Chagas disease in Brazil and Peru, the majority are sylvatic species, associated with a wide variety of habitats and wild animals (many of them reservoirs of Trypanosoma cruzi). However, trends to invade human dwellings and to establish domestic colonies have been observed in several species in the genus (P. geniculatus, P. rufotuberculatus, P. lutzi, P. chinai), while others are opportunistic species (e.g. P. lignarius in the Amazon basin flying from wild ecotopes to houses on occasion without colonizing). Nevertheless, they can play some role in the transmission of sylvatic T. cruzi to humans. Research on the genus Panstrongylus requires some focus on investigating the natural ecology of these species. This knowledge would add to our understanding of their evolutionary potential and may assist in predicting new epidemiological scenarios, for which new control strategies need to be devised.