Meeting Abstract

S7.3-4  Monday, Jan. 6 15:00  First, do no harm: Challenges to controlling another organism’s nervous system FAULKES, Z; The University of Texas-Pan American

Parasites, particularly those with complex life cycles requiring multiple hosts, often manipulate the behaviour of their hosts to ensure infection by subsequent hosts. Parasites attempting to manipulate the behaviour of their hosts face a series of trade-offs. For example, where parasites ultimately live in a host may be a trade-off between access and damage to the host’s “control centers” (usually the central nervous system). Presumably, an ideal place for parasites to manipulate their host’s behaviour would be from inside the host’s nervous system, but penetrating the nervous system may cause unwanted damage by disrupting synaptic connections or killing neurons. Similarly, hosts with fewer neurons in their nervous systems may be easier to manipulate, but accidental damage of neurons is more likely to have unwanted effects. If the ability of an individual parasite to change host behaviour is small, the number of parasites infecting a host may represent another trade-off between effective control and damage to the host. The infection of white shrimp (Litopenaeus setiferus) by larval tapeworms (Polypocephalus sp.) will be used as a case study. The tapeworms live inside the nervous systems of their host by the hundreds. This would seem to post great risk of damaging synaptic connections between neural circuits, but tapeworm infections do not appear to cause any severe behavioural abnormalities in the shrimp, but do change the shrimp’s activity in more subtle ways.