Table 1.
Overview and outcome of potential conflicts over host manipulation between parasites
| Host | Parasite 1 | Parasite 2 | Outcome of the conflict | Ref. | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Species | Aim | Manipulationa | Proposed mechanisms | Species | Aim | Manipulation a | Proposed mechanisms | |||
| Conflict between parasites with different definitive hosts | ||||||||||
| Gammaruspulex (amphipod)N | Pomphorhynchuslaevis (Acanthocephala) | TT to fish | PE: strongly reduced photophobia | Immune system, neuromodulation, serotonin 101 | Polymorphus minutus (Acanthocephala) | TT to birds | PE: Increased vertical distribution, slightly reduced photophobia | Immune system, neuromodulation, serotonin 101 | Intermediate vertical distribution, P. laevis dominates reaction to light | 55 |
| Paracalliopefluviatili (amphipod)N | Acanthocephalusgalaxii (Acanthocephala) | TT to fish | PE: reduced photophobia | Immune system, neuromodulation, serotonin 101 | Microphallus sp. (Trematoda) | TT to birds | None | No clear differences between singly infected hosts | 87 | |
| Batillariaattramentaria (mollusc)N | Cercariabatillariae (Trematoda) | Transmission of cercariae to fish | Habitat change to much lower depths | Unknown | Renicolidae (Trematoda) | Transmission of cercariae to snails | Habitat change to slightly lower depths | Unknown | Intermediate habitat change | 56 |
| Rattusnorvegicus (mamal)E | Toxoplasma gondii (Protozoa) | TT to felines | Partially altered activity | Brain damage, dopamine, testosterone 102 | Toxocaracanis (Nematoda) | TT to canids | Partially decreased activity | Debilitation 103 | No clear differences between singly infected hosts | 58 |
| Mus musculus (mamal)E | Toxoplasma gondii (Protozoa) | TT to felines | Partially altered activity | Brain damage, dopamine, testosterone 102 | Toxocaracanis (Nematoda) | TT to canids | None, but see 104 | Debilitation 103 | No clear differences between singly infected hosts | 57 |
| Conflict between different transmission strategies (i.e. trophic transmission vs. growth and reproduction on/ in the current host) | ||||||||||
| Gammarusinsensibilis (amphipod)NE | Microphalluspapillorobustus (Trematoda) | TT to birds | PE: more risk prone reaction to disturbance | Immune system, neuromodulation, serotonin 101 | Gammarinemagammari (Nematoda) | Ectoparasitic lifestyle | None | Hosts naturally infected with more G. gammari less manipulated, but not experimentally inducible | 60 | |
| Gammarusroeseli (amphipod)N | P. minutus (Acanthocephala) | TT to birds | PE: strongly increased vertical distribution | Immune system, neuromodulation, serotonin 101 | Dictyocoelasp (Microsporidae) | Vertical transmission | Slightly increased vertical distribution | Unknown | Co‐infections resembleDictyocoelasp. infected hosts | 59 |
| Intraspecific conflict between different developmental stages (i.e. trophic transmission vs. growth and development in the current host) | ||||||||||
| Caecidotea intermedius (isopod)N | Acanthocephalusdirus (infective) (Acanthocephala), | TT to fish | PE: colour change | Carotenoid based colouration of the parasite 105 | A. dirus (not‐yet infective) | Growth and development | Slight colour change | Carotenoid based colouration of the parasite 105 | Co‐infections resemble hosts with infective parasites | 61 |
| G. pulex NE | P. laevis (infective) (Acanthocephala), | TT to fish | PE: reduced photophobia | Immune system, neuromodulation, serotonin 101 | P. laevis (not‐yet infective) | Growth and development | None 73 | Infective stages dominates, trend for slight effect of the not‐yet infective stage | 63 | |
| Macrocyclops albidus (copepod)E | Schistocephalus solidus (infective) (Cestoda), | TT to fish | None, but see 39, 65, 106 | Unknown | S. solidus (not‐yet infective) | Growth and development | PS: Reduced activity | Unknown | Infective stage dominates, no effect of one or multiple not yet infective stages | 64 |
| M. albidus E | Camalanus lacustris (infective) (Nematoda), | TT to fish | PE: slightly increased activity, slightly reduced recovery time | Unknown | C. lacustris (not‐yet infective) | Growth and development | PS: Reduced activity, increased recovery time | Unknown | Infective stage dominates, no effect of one not yet infective stages | 40 |
| Gasterosteus aculeates (fish)E | S. solidus (infective) (Cestoda), | TT to birds | PE: increased risk taking | Brain monoamines 107, energy drain 76, 108 | S. solidus (not‐yet infective) | Growth and development | None | No clear differences between singly infected hosts, mixed infections increase risk taking beyond infective parasites | 76 | |
| Interspecific conflict between different developmental stages (i.e. trophic transmission vs. growth and development in the current host) | ||||||||||
| M. albidus E | C. lacustris (infective) (Nematoda), | TT to fish | PE: slightly increased activity, slightly reduced recovery time | Unknown | S. solidus (not‐yet infective) | Growth and development | PS: Reduced activity and increased recovery time | Unknown | Infective stage dominates, no effect of one not yet infective stages | 40 |
| M. albidus E | S. solidus (infective) (Cestoda), | TT to fish | None, but see 39, 65, 106 | Unknown | C. lacustris (not‐yet infective) | Growth and development | PS: Reduced activity and increased recovery time | Unknown | Both parasites affect host behaviour | 40 |
N, Natural infections; E, Experimental infections; PE, Predation enhancement; PS, Predation suppression; TT, Trophic transmission.
a
Only host manipulation observed by the study investigating the conflict. For many host‐parasite systems host manipulation of the same or other traits has been shown by other studies.