Sammendrag
Direct consumption on free-living cercariae stages of trematodes by non-host organisms interferes with trematode transmission
and leads to reduced infections in the next suitable hosts. Consumer functional responses provide a useful tool to examine
relationships between consumption rates and ecologically relevant prey densities, whilst also accounting for abiotic factors that
likely influence consumption rates. We investigated how temperature influences the consumer functional response of the
amphipod Gammarus lacustris towards the cercariae of three freshwater trematodes (Diplostomum, Apatemon and
Trichobilharzia). Amphipods displayed different functional responses towards the parasites, with Type II responses for
Diplostomum and Type I responses for Apatemon prey. Temperature did not alter the consumption rate of the amphipod predator.
Trichobilharzia was likely consumed at similar proportions as Diplostomum; however, this could not be fully evaluated due to
low replication.Whilst Type II responses of invertebrate predators are common to various invertebrate prey types, this is the first
time a non-filter feeding predator has been shown to exhibit Type I response towards cercarial prey. The prey-specific consumption
patterns of amphipods were related to cercarial distribution in the water column rather than to the size of cercariae or
temperature influence. The substantial energy flow into food webs by non-host consumer organisms highlights the importance
of understanding the mechanisms that modulate functional responses and direct predation in the context of parasitic organisms.
Predator-prey . Cercariae . Transmission interference . Gammarus lacustris
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