Obligate development of Blastocrithidia papi (Trypanosomatidae) in the Malpighian tubules of Pyrrhocoris apterus (Hemiptera) and coordination of host-parasite life cycles

Abstract

Blastocrithidia papi is a unique trypanosomatid in that its life cycle is synchronized with that of its host, and includes an obligate stage of development in Malpighian tubules (MTs). This occurs in firebugs, which exited the winter diapause. In the short period, preceding the mating of overwintered insects, the flagellates penetrate MTs of the host, multiply attached to the epithelial surface with their flagella, and start forming cyst-like amastigotes (CLAs) in large agglomerates. By the moment of oviposition, a large number of CLAs are already available in the rectum. They are discharged on the eggs' surface with feces, used for transmission of bugs' symbiotic bacteria, which are compulsorily engulfed by the newly hatched nymphs along with the CLAs. The obligate development of B. papi in MTs is definitely linked to the life cycle synchronization. The absence of peristalsis allow the trypanosomatids to accumulate and form dense CLA-forming subpopulations, whereas the lack of peritrophic structures facilitates the extensive discharge of CLAs directly into the hindgut lumen. The massive release of CLAs associated with oviposition is indispensable for maximization of the infection efficiency at the most favorable time point.

Development of Phytomonas lipae sp. n. (Kinetoplastea: Trypanosomatidae) in the true bug Coreus marginatus (Heteroptera: Coreidae) and insights into the evolution of life cycles in the genus Phytomonas

“…All measurements of cells (n = 25) and statistical analysis were performed in UTHSCSA Image Tool for Windows v. 3.0. For transmission and scanning electron microscopy the samples were fixed and processed as described previously [37].…”

If host is refractory, insistent parasite goes berserk: Trypanosomatid Blastocrithidia raabei in the dock bug Coreus marginatus

“…All cell measurements (n = 25) and statistical analysis were performed in UTHSCSA Image Tool for Windows v. 3.0. For transmission and scanning electron microscopy the samples were fixed and processed as described previously [30].…”

“…Some dixenous trypanosomatids pass from the gut to the hemolymph of the insect host in order to reach the salivary glands (which have no direct connection with the digestive tract) and, thereby, ensure their transmission to a plant or a vertebrate [26]. In monoxenous species, the hemolymph infection is very rare, since it does not provide a considerable advantage to the parasites, but requires elaboration of expensive mechanisms for exit from the gut and defense against immune system of the host.…”

“…However, as for the majority of monoxenous trypanosomatids, the life cycles of Blastocrithidia spp. are largely unknown [26]. There are only two exceptions: B. triatomae from the predatory triatomine bugs and B. papi from the omnivorous firebug Pyrrhocoris apterus [27][28][29][30].…”

“…This parasite is able to destroy the midgut epithelium and induce pathological changes in Malpighian tubules [33,34]. The development of B. papi in the Malpighian tubules of the firebug Pyrrhocoris apterus leads to their obstruction and reduction of microvilli because of intensive proliferation and attachment of epimastigotes, respectively [30].…”