The effect of Formicae on the survivorship of Homoptera aphididae.

This experiment investigated whether Homoptera aphididae were actually participating in a mutualistic relationship with Formicae sp.. We observed how many aphids were eaten by predators when ants were present, and when ants were absent. We located 24 aphid colonies on Populus grandidentatta. Ants were removed from half of the aphid colonies. We introduced lady beetles (Hippodamia conergens) and lacewing larvae (Chrysoperia carnea) which are aphid predators, to the colonies. We then timed how long it was until aphids were eaten, or the predators were removed. We found that the ants protected the aphid colonies very successfully. The predators consumed aphids in the absence of ants 56% of the time, but there was only one instance in which an aphid was consumed in the presence of ants. The ants were also extremely successful in removing any potential predators from the aphid colonies, when ants were present the predator was removed 87% of the time. Through repeated trials we were able to deduce that these trends were consistent, and that aphids do in fact benefit from their relationship with ants through decreased predation.http://deepblue.lib.umich.edu/bitstream/2027.42/54735/1/3176.pdfDescription of 3176.pdf : Access restricted to on-site users at the U-M Biological Station