Importance and Physiological Effects of Hemolymphagy in Triatomines (Hemiptera: Reduviidae)

Abstract

Triatomines are hematophagous insects and the vectors for Trypanosoma cruzi in the Americas. Although their preferred meal is blood from vertebrate hosts, unfed triatomine nymphs are often seen feeding on different arthropod species. Triatomine saliva has a wide range of activities that aid the hematophagic process. However, nothing is known about its role during hemolymphagy. In the current study, we reproduced hemolymphagy under laboratory conditions and evaluated the influence of hemolymphagy on the survival of Triatoma infestans nymphs. The effects of saliva on the activation of the prophenoloxidase cascade in the invertebrate host and the influence of the saliva on the motility of the bugs and contractions of the dorsal vessels were assessed. Hemolymphagy prolonged the survival rate of T. infestans first instars from 60 to >120 d compared with unfed nymphs. The saliva from T. infestans caused a 50% reduction in the amplitude and frequency of the dorsal vessel contractions of adult Rhodnius prolixus and induced paralysis for >10 min when the saliva was injected into second instars. T. infestans saliva was able to inhibit the activation of the prophenoloxidase cascade from a R. prolixus hemolymph, but had no effect on the phenoloxidase activity after the cascade was activated. The paralyzing molecule in the saliva was <5 kDa and probably had no proteic or lipidic characteristics. These results suggest that triatomine saliva may play an important role during hemolymphagy by inducing paralysis and suppressing immune responses in the invertebrate host. The importance of hemolymphagy for the survival of nymphs in periods when vertebrate blood is scarce is also discussed.

Identification of Bloodmeal Sources andTrypanosoma cruziInfection in Triatomine Bugs (Hemiptera: Reduviidae) From Residential Settings in Texas, the United States

“…In addition, the woodrat nests from which the specimens were collected had signs of recent activity and woodrats were noted to be present at the sites (Charles et al 2013), further corroborating the woodrat DNA-positive results. If an adult triatomine had fed on a human host and then returned to the woodrat nest, it is plausible that the nymphs ingested human blood while feeding on the engorged adult (Wood and Wood 1941, Ryckman 1951, Hays 1965, Alves et al 2011). In this study, no adult specimens collected from woodrat nests or any other location at these two sites were positive for human DNA.…”

Ontogeny, species identity and environment dominate microbiome dynamics in wild populations of kissing bugs (Triatominae)

“…This disparity may stem from inconsistencies between individual sample sets and methodology, but could also reflect Triatominae true biological characteristics. These include lengthy development times through five nymphal instars [38,42], complex physiology of the alimentary tract [38], and accessory feeding strategies, like hemolymphagy (feeding on arthropod haemolymph), kleptohematophagy (stealing a blood meal from another triatomine), and coprophagy (feeding on faeces) known to be employed by some triatomine species [2,[45][46][47][48].…”

Isolation and molecular characterization of a major hemolymph serpin from the triatomine, Panstrongylus megistus

“…Triatomines are exclusively hematophagous, hemimetabolic insects, passing through five nymphal instars before emerging as adults [9,10]. One triatomine vector species, Rhodnius prolixus , is easily raised in the laboratory and also usually molts following each blood meal so that these characteristics have contributed to this insect becoming a model for physiological studies [9].…”