title: Impacts of temperature and crowding on sex ratio, fecundity and Wolbachia infection intensity in the copepod, Mesocyclops thermocyclopoides.
abstract: Wolbachia are a group of intracellular bacteria that cause reproductive alterations in arthropods. Here, we describe the effects of two environmental factors (crowding and temperature) on phenotypic expression of feminization, the host's fecundity and Wolbachia infection intensity among life cycle stages in the naturally Wolbachia-infected copepod, Mesocyclops thermocyclopoides. The copepod was first found to be co-infected with Wolbachia A- and B-supergroups Wolbachia strains based on wsp primers. The relative Wolbachia infection intensity within individuals was determined using quantitative real-time PCR and was significantly higher in the B-supergroup than in the A-supergroup. Experimental results of temperature effect on bacterial density in each developmental stage revealed a significant decrease in Wolbachia infection intensity following exposure to high temperature (37°C) in both sexes and implied that Wolbachia might survive in room temperature (25°C) better than in high temperature. Experimental results of crowding effects on Wolbachia infection intensity suggested a negative correlation between copepod nauplii and Wolbachia infection intensity. No effect of rearing temperature on the sex ratio was reported although the fecundity was significantly decreased by high temperature. The results showed that Wolbachia infection intensity to be correlated with crowding conditions and was decreased following exposure of elevated temperature.
authors.affiliation: Department of Plant Production Technology, Faculty of Agricultural Technology, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand. Electronic address: itsanun.wi@kmitl.ac.th.
authors.forename: Itsanun
authors.initials: I
authors.lastname: Wiwatanaratanabutr
authors.affiliation: UFR Sciences Fondamentales et Appliquées, Laboratoire Ecologie et Biologie des Interactions - UMR CNRS 7267 Equipe Ecologie Evolution Symbiose, Université de Poitiers, France.
authors.forename: Frederic
authors.initials: F
authors.lastname: Grandjean
mesh_terms: D000818:Animals; D033342:Copepoda / Q000382:microbiology*; D005260:Female; D005298:Fertility; D016905:Gram-Negative Bacterial Infections / Q000662:veterinary*; D006358:Hot Temperature; D008297:Male; D060888:Real-Time Polymerase Chain Reaction; D012744:Sex Ratio; D020577:Wolbachia
keywords: Copepod; Crowding; Infection intensity; Sex ratio; Temperature; Wolbachia