Toltrazuril (Baycox®vet.) in feed can reduce <em>Ichthyophthirius multifiliis </em>invasion of rainbow trout (Salmonidae)

Various compounds have been applied for control of Ichthyophthirius multifiliis (commonly known as Ich) which is the parasitic pathogen, responsible for the white spot disease, in freshwater aquaculture worldwide.  Available methods are based on disinfection of fish tank water, targeting infective free-swimming theronts and escaped tomonts. No legal drug is available and licensed for treatment or prevention of the disease. The presently reported study was performed to test the potential of toltrazuril (Baycox® vet.)—a drug licensed for treatment of coccidial infections in other animal species—to reduce Ich infections when administered orally. Commercial pelleted feed containing 5.0 or 2.5 mg toltrazuril per 1 g of feed was offered to rainbow trout, Oncorhynchus mykiss(Walbaum, 1792) (Actinopterygii: Salmoniformes: Salmonidae), during a three day feeding regime (1% of biomass offered per day). Two trials were performed: one with feeding before exposure to parasites and one where already infected fish were treated. Before the treatment it was tested if fish would eat feed containing different drug concentrations and it was found that feed with the high drug concentration was not eaten by the fish whereas all feed containing 2.5 mg per 1 g feed was eaten. Following the exposure to infective I.multifiliis theronts it was found that the fish treated with toltrazuril before challenge obtained a significantly lower parasite burden (number of trophonts in the skin) compared to untreated control. On the other hand, toltrazuril proved to be ineffective when administered to the fish which were already infected before the treatment

Comparative efficacies of sodium percarbonate, peracetic acid and formaldehyde for control of Ichthyobodo necator:an ectoparasitic flagellate from rainbow trout

Background. Ichthyobodosis (“costiosis”) is induced by the flagellate Ichthyobodo necator in both wild and cultured host populations. Fish farmers for decades have been using formaldehyde (FA) for control but this compound is problematic due to its carcinogenic and allergenic nature. Alternative auxiliary substances for bath treatment are needed and therefore we decided to compare efficacies of sodium percarbonate (SPC), peracetic acid (PAA), and hydrogen peroxide (HP) for control of ichthyobodosis in rainbow trout, Oncorhynchus mykiss. Materials and methods. An experimental infection of Ichthyobodo necator on rainbow trout (2–3 g) was established (total parasite population up to 142 000 flagellates per fish) and duplicated controlled water bath treatments were conducted with specified water quality criteria. Four compounds: SPC (40, 80, and 120 mg · L–1), PAA (0.1, 0.2, and 0.3 mg · L–1), HP (15 and 30 mg · L–1), and FA (40 and 80 mg · L–1) were tested. The compounds were applied for 2 h (as static freshwater bath treatments at 13°C) in 20-L aerated tanks (containing 10 L of the treatment solution). Results. FA at a concentration of 80 mg · L–1 and PAA at 0.3 mg · L–1 showed almost complete elimination of parasites but it was found that also SPC at a concentration of the 120 mg · L– was highly effective in eliminating I. necator. In addition, SPC and PAA (80 mg · L–1 and 0.2 mg · L–1, respectively) also significantly reduced the parasite load compared to untreated control fish. HP significantly reduced parasite populations at a concentration of 30 mg · L–1, but the compound elicited adverse reactions in fish. Conclusion. It is suggested that SPC and PAA may serve as alternatives to formaldehyde for control of ichthyobodosis in rainbow trout farms

Effects of putative male pheromones on female ratings of male attractiveness: Influence of oral contraceptives and the menstrual cycle

Previous research has revealed that natural and synthetic pheromones can enhance ratings of opposite sex attractiveness. The present study investigated the effects of exposure to male axillary secretions on female ratings of the sexual attractiveness of male stimuli. Thirty-two female undergraduates, half of whom were contraceptive pill users, rated male vignette characters and photographs of male faces on aspects of attractiveness. On two separate study days, corresponding to different phases of their menstrual cycle, stimuli were presented while exposed to male axillary pheromones and under a control condition (no pheromone). The order of testing was balanced with respect to pheromone/control condition and menstrual cycle phase. Pheromone exposure resulted in significantly higher attractiveness ratings of vignette characters and faces. Use of the contraceptive pill or menstrual cycle phase had equivocal effects on some vignette items and neither had any influence on female ratings of male facial attractiveness. The results of this study suggest that exposure to natural male axillary pheromones can significantly enhance female perceptions of various aspects of male attractiveness