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Abstract Pesticide pollution can alter parasite transmission, but scientists are unaware if effects of pesticides on parasite exposure and host susceptibility (i.e. infection risk given exposure) can be generalised within a community context. Using replicated temperate pond communities, we evaluate effects of 12 pesticides, nested in four pesticide classes (chloroacetanilides, triazines, carbamates organophosphates) and two pesticide types (herbicides, insecticides) applied at standardised environmental concentrations on larval amphibian exposure and susceptibility to trematode parasites. Most of the variation in exposure and susceptibility occurred at the level of pesticide class and type, not individual compounds. The organophosphate class of insecticides increased snail abundance (first intermediate host) and thus trematode exposure by increasing mortality of snail predators (top–down mechanism). While a similar pattern in snail abundance and trematode exposure was observed with triazine herbicides, this effect was driven by increases in snail resources (periphytic algae, bottom–up mechanism). Additionally, herbicides indirectly increased host susceptibility and trematode infections by (1) increasing time spent in susceptible early developmental stages and (2) suppressing tadpole immunity. Understanding generalisable effects associated with contaminant class and type on transmission is critical in reducing complexities in predicting disease dynamics in at‐risk host populations.
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Parasite manipulation of host phenotypes inferred from transcriptional analyses in a trematode‐amphipod system
Abstract Manipulation of host phenotypes by parasites is hypothesized to be an adaptive strategy enhancing parasite transmission across hosts and generations. Characterizing the molecular mechanisms of manipulation is important to advance our understanding of host–parasite coevolution. The trematode (Levinseniella byrdi) is known to alter the colour and behaviour of its amphipod host (Orchestia grillus) presumably increasing predation of amphipods which enhances trematode transmission through its life cycle. We sampled 24 infected and 24 uninfected amphipods from a salt marsh in Massachusetts to perform differential gene expression analysis. In addition, we constructed novel genomic tools forO. grillusincluding a de novo genome and transcriptome. We discovered that trematode infection results in upregulation of amphipod transcripts associated with pigmentation and detection of external stimuli, and downregulation of multiple amphipod transcripts implicated in invertebrate immune responses, such as vacuolar ATPase genes. We hypothesize that suppression of immune genes and the altered expression of genes associated with coloration and behaviour may allow the trematode to persist in the amphipod and engage in further biochemical manipulation that promotes transmission. The genomic tools and transcriptomic analyses reported provide new opportunities to discover how parasites alter diverse pathways underlying host phenotypic changes in natural populations.
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- PAR ID:
- 10438747
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Molecular Ecology
- Volume:
- 32
- Issue:
- 18
- ISSN:
- 0962-1083
- Format(s):
- Medium: X Size: p. 5028-5041
- Size(s):
- p. 5028-5041
- Sponsoring Org:
- National Science Foundation
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