Susceptibility of embryos of Biomphalaria tenagophila (Mollusca: Gastropoda) to infection by Pochonia chlamydosporia (Ascomycota: Sordariomycetes)

Abstract The trematode Schistosoma mansoni is a heteroxenous parasite, meaning that during its life cycle needs the participation of obligatory intermediate and definitive hosts. The larval development occurs in aquatic molluscs belonging to the Biomphalaria genus, leading to the formation of cercariae, which emerge to infect the final vertebrate host. For this reason, studies for control of the diseases caused by digenetic trematodes often focus on combating the snail hosts. Thus, the objective of this study was to evaluate the susceptibility of Biomphalaria tenagophila embryos to the fungus Pochonia chlamydosporia (isolate Pc-10) under laboratory conditions. Two experimental groups were formed: the control group, consisting of egg masses not exposed to the fungus; and the treated group, in which the snail egg masses were exposed to mycelium of the fungal isolate (Pc-10). At the end of 15 days, the egg masses were evaluated under a stereomicroscope to analyze the hatching of B. tenagophila embryos in both experimental groups. The entire experiment was conducted in duplicate, with five replicates for each repetition (five egg masses/replicate), utilizing a total of 100 egg masses, with 20 to 30 eggs/egg mass. After 15 days of interaction, the exposure to the fungal hyphae bodies significantly impaired the viability of the B. tenagophila eggs, inhibiting the embryogenesis process by 83.7% in relation to the control group. Transmission and scanning electron microscopic images revealed relevant structural alterations in the egg masses exposed to the hyphae action of the fungus, interfering in the development and hatching of the young snails under analysis. These results indicate the susceptibility of B. tenagophila embryos to the fungus P. chlamydosporia (isolate Pc-10) and suggests the potential of Pc-10 to be used in the control of parasitic agents, such as S. mansoni, but in vivo experiments become necessary.