Infectivity of the parasite <i>Metschnikowia bicuspidata</i> is decreased by time spent as a transmission spore, but exposure to phycotoxins in the water column has no effect

Transmission from one host to another is a crucial component of parasite fitness. For some aquatic parasites, transmission occurs via free-living stage that spends time in the water, awaiting an encounter with new host. These stages can be impacted by biotic and abiotic factors influence parasite's ability successfully infect or grow Here we tested whether spent water column and/or exposure common cyanobacterial toxins stages. More specifically, infectivity, within growth, virulence fungal Metschnikowia bicuspidata changed as result cyanotoxins column. We exposed spores different levels two ecologically important cyanotoxins, microcystin-LR anatoxin-a, factorially manipulated amount were incubated water. removed used those same genotype lake zooplankton Daphnia dentifera. found did not impact fitness (infection prevalence spore yield per infected host) (host lifetime reproduction survivorship) at concentrations (10 30 μg/L). However, spending longer decreased spore's chances for successful infection: only 24 hr approximately 75% hosts, whereas 10 days less than 50% hosts. also negative relationship between final hosts proportion became infected. In treatments where prior encountering host, infection was lower (indicating infectivity), but each yielded more end infection. hypothesise this pattern may intraspecific competition Overall, these results suggest are strongly influenced column, other aspects