Ecology & Evolution Seminar Series 2014-19

Date: 24 July 2014 Time: 12.00 pm

Kirsty Yule presents The enemy of my enemy is my friend: Tri-trophic interactions between a predator-parasite-host assemblage in New Zealand

kirsty New Zealand’s dynamic geological past has generated many biological oddities. One of the most unusual is the largest endemic moth, Aenetus virescens. The larvae of A. virescens are wood-boring parasites who spend ~ 6 years within a host tree, feeding on phloem. Larvae excavate a “7” shaped tunnel that is concealed by a webbing of silk and frass potentially cryptic to predators. The predatory North Island Kaka, Nestor meridionalis septentrionalis excavate bark and wood from trees to obtain A. virescens, often causing extensive damage to the host. Despite the unique life history and ecology of A. virescens, tri-trophic interactions between the parasitic larvae, the host tree and the avian predators remains unresolved.

I propose a trade-off exists between the effort required from larvae to parasitize a host tree, and the protection host trees provide from predating Kaka. I hypothesise that A. virescens select host species based on wood density and phloem reward, and that Kaka attacks are correlated with parasite load. Furthermore, I hypothesise that host tree parasite load is correlated to host size. Preliminary results indicate A. virescens select specific tree species as hosts and that Kaka attacks are correlated to tree parasite load. Furthermore, results show A. virescens aggregation among hosts is influenced by tree size, supporting the target area effect, whereby larger trees harbour greater numbers of parasites. This tri-trophic system presents a novel predator-parasite-host relationship whereby predators directly influence parasites and their hosts.

For more information, please contact Steph Price on Steph.Price@vuw.ac.nz