A common scheme of sponge is to manipulate the behavior of their hosts to help with their transmission system to another host . Thezombie ant fungus , for example , get the insect to die while burn down on a plant , which gives the fungus a high platform for shooting out spore . In the state of nature , hosts can entertain multiple parasite , and sometimes they work together to interpolate the behavior of the host even more dramatically . But what if the parasites have vie interests ? allot to astudypublished inEvolutionlast week , one leech could counteract the other , suppressing its core on their apportion host .
Schistocephalus solidusis a bloodsucking tapeworm with acomplicated living rhythm involving three separate hosts : modest crustacean call copepod , then fish , then shuttlecock . After issue from its eggs , the youthful , innocent - swimming leech infect a copepod crustacean . After an infected copepod crustacean is eaten by a Pisces the Fishes , the sponger keep on to acquire until the fish , in turn , is ingest by a snort . Here , in its final bird host , the worm produce into an grownup and produces testis . These tapeworms are know to manipulate their hosts bet on what developmental leg they ’re at . Previous experimentation unveil how infecting copepods with younger cestode ( who are n’t quick to move on to fish yet ) results in copepod crustacean that are less active than clean copepods , Nature cover , making them less likely to be eaten by fish . When they ’re quick , the sponge make the copepods become more active and blazing to angle .
However , few discipline have examined the effect of multi - parasite fundamental interaction on host manipulation . So , Nina HaferandManfred Milinski from the Max Planck Institute for Evolutionary Biologyin Germany taint copepods withSchistocephalus solidusto see if there ’s any experimental evidence for sabotage . When the co - infecting parasites have the same end — making the infect copepod crustacean more combat-ready , for example — they enhance each other ’s manipulation , making the copepod even more active than it would be if it only had one parasite .
However , if the co - infecting parasites are of different ages , they differ over how they should manipulate the host . In that case , the infectious , older sponge wins the fight , suppressing the manipulation of its non - infective , younger rival . The younger parasite ends up get no effect whatsoever on the host ’s behavior . This suggests that the older parasite is sabotaging the younger one ’s bodily function , Hafer tells Nature , because “ we do n’t expect the non - infective sponger to stop what it ’s doing . ” The findings support both cooperation in and sabotage of host handling , the authors write , and show one sponger can neutralize manipulation by another .
