Abstracts (first author)
Walking with insects: molecular mechanisms behind parasitic manipulation of caterpillar behaviour
Parasitic modification of host behaviour is a widely adopted strategy of parasites to enhance their own transmission. The examples of behavioural manipulation are rapidly accumulating, covering a broad spectrum of parasites and hosts. Nevertheless, surprisingly little is known on the underlying causative molecular mechanisms. A typical case of behavioural manipulation is found in insects infected with baculoviruses. Infected caterpillars show enhanced mobility and start climbing to the top of plants or the forest canopy (‘tree top disease’). As a consequence, the virus is spread over a larger area, thereby increasing the chance to infect a new caterpillar. The baculovirus-insect system provides an excellent platform to study parasitic manipulation of insect host behaviour. It allows the comparative analysis between wildtype viruses and single gene knock-out mutants. Recently, the egt gene from the baculovirus Lymantria dispar nucleopolyhedrovirus (LdMNPV) was identified to induce tree top disease in Lymantria dispar larvae. Here, we studied the effect of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) on climbing behaviour in two different host insects, the cabbage looper Trichoplusia ni and the beet armyworm Spodoptera exigua. We show that the effect of this virus on caterpillar behaviour differs between these two host species. Additionally, we found no evidence for a general role of the egt gene in causing tree top disease. This implies that baculoviruses have evolved multiple strategies to manipulate similar behavioural phenotypes in their caterpillar hosts.