Cannibalism and Coprophagy Are Modes of Transmission of Blastocrithidia triatomae (Trypanosomatidae) between Triatomines

Abstract

Transovarial transmission was not detectable among Blastocrithidia triatomae-infected Triatoma infestans. Rather, B. triatomae was transmitted directly between triatomines by cannibalism and coprophagy. Cannibalism conditions that excluded coprophagy always resulted in an infection of Dipetalogaster maxima. The efficiency of transmission was not influenced by the blood source--mice or chickens--fed to the infected donor bugs although chicken blood lyses the epimastigotes of the stomach population. Triatoma infestans was infected by coprophagy only if fed, not if unfed. Blastocrithidia triatomae in dry feces was taken up only if the feces were redissolved in fresh feces. Infections also appeared in groups of bugs fed on chickens previously used for feeding infected bugs.

The ecotopes and evolution of triatomine bugs (triatominae) and their associated trypanosomes

“…A comparative analysis of the five vectors phylogeny with the inclusion of other insects, particularly termites, harboring protozoan endosymbionts provides several lines of evidence that faecal transmission is ancestral. In addition, triatomines demonstrate exclusive cophageny for bacterial symbionts (Durvasula et al 1999), and predominant cophageny for the triatomine pathogen Blastocrithidia triatomae (Schaub et al 1989). The evidence suggests that the original bug-borne trypanosome "hijacked" the natural mechanism of endosymbiont transmission.…”

Ammonia attracts the haematophagous bug Triatoma infestans : behavioural and neurophysiological data on nymphs

“…However, there are other advantages. A special case documented for triatomines is the transfer of symbionts via coprophagy and cannibalism (Ryckman 1951;Schaub et al 1989). These symbionts, which are essential for triatomine development, are mainly transferred via coprophagy on wet faeces (Schaub et al 1989).…”

“…A special case documented for triatomines is the transfer of symbionts via coprophagy and cannibalism (Ryckman 1951;Schaub et al 1989). These symbionts, which are essential for triatomine development, are mainly transferred via coprophagy on wet faeces (Schaub et al 1989). Juvenile stages of¯eas have also been reported to perform coprophagy (Lewis 1995): The larvae of these insects do not parasitise hosts but ful®ll their blood requirement by feeding on the faeces of the bloodsucking adults which in the case of¯eas consists of remnants of digested blood of previous meals, and droplets of virtually undigested blood.…”

“…When defecating, the bugs show a stereotypic behaviour: after emerging from the refuge, the bugs turn 180°, walk backwards and defecate down the wall (Lorenzo and Lazzari 1996). Defecating outside the refuge is all the more signi®cant since the faeces also serves as the mode of transmission for triatomine pathogens (Schaub et al 1989(Schaub et al , 1992. Defecating outside would therefore serve the dual purpose of keeping the refuge as clean as possible while simultaneously permitting re-wetted faeces to serve as a guide to these night active bugs returning from a blood-meal or to guide those bugs newly seeking a viable refuge.…”

“…Marking a speci®c refuge with faeces would further serve to inform other bugs of the suitability of its location in the vicinity of hosts, as defecation occurs primarily in a few days after a blood-meal (Wigglesworth 1931). Aggregation within speci®c refuges would promote gene transfer, transmission of symbionts needed for development of young stages via coprophagy (Baines 1956;Schaub et al 1989), and cannibalism, where unfed nymphs feed on engorged individuals (Ryckman 1951;Schaub et al 1989). The latter phenomenon could be expected to be of most bene®t to the youngest stages which have not yet learned the way to the host and which have relatively small blood requirements.…”