Learning and memory enable organisms to adjust to changing environmental stimuli. To maintain flexibility learned associations decay if they are not reinforced. This can create a trade-off between persistence and flexibility. In social insects, colonies can retain memories beyond the capacity of individual workers by forming information centers. We hypothesized that the seed cache provides one mechanism for this information storage. To test this, we fed colonies of the seed harvester ant P. rugosus a novel seed (Kentucky Bluegrass) in treatments of either high or low amounts. After feeding for seven days, we assessed colonies for recognition by placing a patch of seeds across an active foraging trail and recording the proportion of foragers that handled a seed. We then withheld seeds but continued to assess seed recognition weekly for a total of 280 days. Colonies fed both low and high seed levels showed similar patterns of decay in seed recognition. Our data, coupled with those of Johnson et al (1994) suggest that the seed cache functions for long term information storage, but they do not indicate whether seed levels affect duration of long term recognition. One reason for this could be high seed numbers; even though initial treatments differed in approximately 400,000 seeds, both treatments could have provided enough seeds to over-saturate the cache.
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA