title: Fasciola hepatica: effect of the natural light level on cercarial emergence from temperature-challenged Galba truncatula.
abstract: As abrupt changes in water temperature (thermal shock) triggered a significantly greater cercarial emergence of Fasciola hepatica from experimentally infected Galba truncatula, laboratory investigations were carried out to study the influence of light on cercarial emergence in snails subjected to a thermal shock every week (a mean of 12 °C for 3 h) during the patent period. Thermal shock for these temperature-challenged (TC) snails was carried out outdoors under artificial or natural light, or indoors under constant artificial light. Compared with the infected control snails always reared indoors at 20 °C, the number of cercariae in TC snails subjected to a thermal shock and natural light outdoors was significantly greater. The repetition of this experiment by subjecting TC snails to the same thermal shock indoors under an artificial light level ranging from 600 to 3000 lux did not show any significant difference among the numbers of cercariae in the different subgroups. A detailed analysis of the results noted in the TC snails subjected to natural light during the thermal shock demonstrated that the number of cercariae-releasing snails was significantly higher between 601 and 1200 lux and for the highest nebulosity values (7-8 octas, which corresponds to a sufficiently or completely overcast sky). Contrary to the intensity of artificial light, which did not influence cercarial emergence, the natural light level had a significant effect on this process when F. hepatica-infected snails were subjected to a regular thermal shock during the patent period.
authors.affiliation: INSERM 1094, Faculties of Medicine and Pharmacy, 87025 Limoges, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Vignoles
authors.affiliation: PADESCA Laboratory, Veterinary Science Institute, University Constantine 1, 25100 El Khroub, Algeria.
authors.forename: Amal
authors.initials: A
authors.lastname: Titi
authors.affiliation: INSERM 1094, Faculties of Medicine and Pharmacy, 87025 Limoges, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rondelaud
authors.affiliation: PADESCA Laboratory, Veterinary Science Institute, University Constantine 1, 25100 El Khroub, Algeria.
authors.forename: Abdeslam
authors.initials: A
authors.lastname: Mekroud
authors.affiliation: INSERM 1094, Faculties of Medicine and Pharmacy, 87025 Limoges, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Dreyfuss
mesh_terms: D000818:Animals; D058487:Cercaria / Q000502:physiology*; D005210:Fasciola hepatica / Q000254:growth & development / Q000528:radiation effects*; D005602:France; D006790:Host-Parasite Interactions; D006358:Hot Temperature; D008029:Lighting; D012542:Scattering, Radiation; D012908:Snails / Q000469:parasitology*; D013472:Sunlight; D014867:Water / Q000469:parasitology
chemical_list: D014867:Water