PARENT SESSION
Oral Session # 73: Invasive Species VI: Terrestrial.
Presiding: S DeWalt
Thursday, August 7. 8:00 AM to 11:30 AM, SITCC Meeting Room 204.
Invasive ants and gall-wasp mutualisms and commensalisms.
Inouye, Brian*,1, 1 Florida State University, Tallahassee, Florida
ABSTRACT- Oak trees host diverse communities of cynipid gall wasps, parasitoids and inquilines. Ants can mediate several interactions among gall wasps and their parasitoids found on Quercus lobata and Q. douglassi. I present experimental and observational data on a mutualism between ants and a cynipid wasp whose galls secrete 'honeydew', and an indirect commensalism with a different species of cynipid wasp that benefits from the presence of ants but provides no reward. Using ant exclusions, I show that the presence of tending ants lowers the rate of attack by a diverse assemblage of parasitoids, and also changes the set of species that can successfully use different galls. Additionally, the species of tending ants (Linepithema humile vs Liometopum occidentale) affects the overall rate of parasitoid attack and the proportions of different parasitoid species that emerge from galls. Invasive argentine ants fulfill a similar role to native ants in some mutualisms (but not all), but have a much weaker interaction than native ants in an indirect commensalism with a gall wasp.
Key words: invasive species, host-parasitoid interaction, cynipid gall wasps, ant mediated mutualism