Multi-Species Interactions Among a Commensal (Chaetogaster limnaei limnaei ), a Parasite (Schistosoma mansoni ), and an Aquatic Snail Host (Biomphalaria glabrata)

Abstract

This study assessed the effects of a commensal, Chaetogaster limnaei limnaei, and a parasitic trematode, Schistosoma mansoni, on infection patterns and life-history responses in the aquatic snail Biomphalaria glabrata. Prevalence of infection was significantly higher in snails that were devoid of C. limnaei limnaei relative to those that were colonized by the commensal, indicating that the oligochaete may protect the host from trematode infection. This finding appeared to be the direct result of the commensal as opposed to indirect stimulation of the immune system, as hemocyte numbers did not differ between C. limnaei limnaei-colonized and noncolonized snails. Snail growth and reproduction were affected by the presence of C. limnaei limnaei and exposure to S. mansoni. Two-way ANOVA revealed a significant effect of both C. limnaei limnaei presence and trematode exposure on B. glabrata growth over the 5-wk study with C. limnaei limnaei-colonized and parasite-infected snails demonstrating the greatest growth. Snails exposed, but uninfected, by S. mansoni demonstrated the lowest growth regardless of commensal colonization. Chaetogaster limnaei limnaei colonization had no effect on egg production, but S. mansoni-infected snails produced significantly more eggs than individuals from other treatment groups. Survival remained over 85% in all treatment groups. The ecological implications of these results are discussed.

Experimental evaluation of Candonocypris novaezelandiae (Crustacea: Ostracoda) in the biocontrol of Schistosomiasis mansoni transmission

“…They also found that experimental infection of Biomphalaria glabrata (B. glabrata) snails with schistosome miracidia and the total periodic cercarial production were significantly reduced by Psychoda in comparison with the control group. The prevalence of infection by S. mansoni in B. glabrata was significantly higher in snails that were devoid of Chaetogaster limnaei (Oligochaeta: Annelida), indicating that such oligochaete may protect the host from trematode infection [7,15] . The reduction of the cercarial production from infected snails by C. novaezelandiae may be explained by the predatory effect of this organism on the cercariae.…”

“…To study the effect of eggs density on the predatory activity of C. novaezelandiae, a number of Petri dishes containing 50 mL dechlorinated water were provided each with 100 C. novaezelandiae and different numbers of B. alexandrina eggs (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) egg masses containing 22-371 eggs). Three replicates were set up and all Petri dishes were maintained at (25依2) °C in the laboratory and examined after 24 h using a stereomicroscope.…”

New scope on the relationship between rotifers and Biomphalaria alexandrina snails

“…Apparently, a state of tolerance occurred between the snail and the invader rotifer, because it didn't induce any detectable host response. Coadaptations within the snail host have been suggested in different snail species [11] .…”

“…The pathological impact of rotifers isolated from snails has been reported to affect egg masses and newly hatched snails, rather than mature snails [22] . It was reported that Chaetogaster metazoan could protect B. glabrata against infection with S. mansoni without interfering with the snail growth or fecundity [11] . In the present study, infection with S. mansoni was successfully established in SG II-A snails, as proved by the histological appearance of well developed cercariae inside the snails, along with the remarkable cercarial output throughout the four weeks shedding duration.…”

“…Indeed, snails thrive in nature under diverse and changing environmental conditions [8] . Numerous metazoa have been described as living in close association with snails [9][10][11] . Occurrence of many diverse organisms within snails is not surprising, since the snail's natural habitats are shared by…”