Experimental habitat fragmentation disrupts host-parasite interaction over decades via life-cycle bottlenecks

Habitat loss and fragmentation are likely to seriously impact parasites, a less studied but critical component of ecosystems, yet we lack long-term experimental evidence. Parasites structure communities, increase connectivity in food webs, and account for a large proportion of an ecosystem’s total biomass. Food web models predict that parasites with multiple obligate hosts are at greater risk of extinction because the local extinction, or reduction in abundance, of any host will result in a life-cycle bottleneck for the parasite. We examine the response of a parasite and its multiple hosts to forest fragmentation over 26 years in the Wog Wog Habitat Fragmentation Experiment in southeastern Australia. The parasite is the nematode Hedruris wogwogensis, its intermediate host is the amphipod, Arcitalitrus sylvaticus, and its definitive host is the skink, Lampropholis guichenoti. In the first decade after fragmentation, nematodes completely disappeared from the matrix (plantation forestry)...