ABSTRACT
Interactions of holoplanktonic mollusks with symbionts and parasites are poorly known. We investigated the ecology of infection (prevalence, intensity, and abundance) in Firoloida desmarestia, caught during two sampling campaign sessions in 2012, off the Baja California Peninsula, Mexico (IMECOCAL, 83 stations) and a coastal research center near La Sorpresa Beach, Baja California Sur, in the Gulf of California (14 stations). Only females of F. desmarestia were parasitized. Hemiuroidea parthenita rediae infected 1% of F. desmarestia population at IMECOCAL, whereas young unencysted metacercariae stages of Opechona pyriformis (Lepocreadiidae) parasitized 6.6% of the same host species at La Sorpresa. Overall, finding of rediae and metacercariae represent new geographical and host records and shows that F. desmarestia has a dual host function in the life cycle of trematodes. As first intermediate host, F. desmarestia harbors hemiuroid rediae, functioning as the source of infection to other zooplanktonic groups by dispersing successive cercariae. As second intermediate hosts, it harbors infective unencysted metacercariae stages of O. pyriformis, which parasitize nektonic predators (fish), most likely through trophic interaction. Our results suggest that some trematodes are able to spend their entire life cycle infecting only pelagic hosts. Parasite-F. desmarestia interaction is shown in a conceptual model, where we propose that transmission of trematodes may occur between individuals of F. desmarestia within the same swarm. Relevance of F. desmarestia as a potential host in which life cycle abbreviation of trematodes may take place is discussed. This is the first quantitative study of helminth interaction on F. desmarestia in the Eastern Pacific.
Subject(s)
Gastropoda/parasitology , Metacercariae/isolation & purification , Trematoda/isolation & purification , Trematode Infections/epidemiology , Trematode Infections/veterinary , Animals , California/epidemiology , Female , Host Specificity , Host-Parasite Interactions , Life Cycle Stages/physiology , Mexico/epidemiology , Trematode Infections/parasitologyABSTRACT
SUMMARY A food-borne trematode infection fascioliasis is one among common public health problems worldwide. It caused a great economic loss for the human race. Control of snail population below a certain threshold level is one of the important methods in the campaign to reduce the incidence of fascioliasis. The life cycle of the parasite can be interrupted by killing the snail or Fasciola larva redia and cercaria inside of the snail Lymnaea acuminata. In vitro toxicity of different binary combinations (1:1 ratio) of plant-derived larvicidal active components such as citral, ferulic acid, umbelliferone, azadirachtin and allicin against Fasciola redia and cercaria were tested. The mortality of larvae was observed at 2h, 4h, 6h and 8h of treatment. In in vitro condition azadirachtin + allicin (1:1 ratio) was highly toxic against redia and cercaria (8h LC50 0.006 and 0.005 mg/L). Toxicity of citral + ferulic acid was lowest against redia and cercaria larvae. .
RESUMO A infecção alimentar pelo trematóide da fasciolíase é uma dentre os mais comuns problemas de saúde pública mundiais, causando grande prejuízo econômico para a humanidade. Controle da população de caramujos abaixo de determinado nível é um dos métodos no campo mais importantes para a redução da incidência da fasciolíase. O ciclo de vida do parasita pode ser interrompido pela morte do caramujo ou da larva redia e cercária da Fasciola dentro da Lymnaea acuminata. Foi testada a toxicidade in vitro das diferentes combinações binárias (relação 1:1) entre os vários componentes larvicidas ativos da planta tais como citral, ácido ferúlico, umbeliferone, azadiractina, e alicina contra a Fasciola redia e a cercária. A mortalidade das larvas foi observada após duas, quatro, seis e oito horas de tratamento. A condição in vitro azadiractina + alicina (relação 1:1) foi altamente tóxica contra redia e cercária (8h LC50 0,006 e 0,005 mg/L). Toxicidade do citral + ácido ferúlico foi a mais baixa contra redia e larvas de cercária. .