The effect of colony structure on intracolony food distribution in the odorous house ant (Tapinoma sessile) as revealed by a protein marker

Matthew T VanWeelden, Purdue University

Abstract

Colony structure in the odorous house ant Tapinoma sessile (Say) expresses a wide variety of spatial configurations, in contrast to other species of Hymenoptera. Colonies range from small single nest units to large multinest supercolonies. The polygynous nature of the odorous house ant, coupled with its ability to establish supercolonies proves to be a substantial obstacle in pest management operations, as the elimination of all nests is required to fully prevent reemergence. To improve the efficacy of baiting techniques, analysis on the distribution of food throughout the colony is required. We examined the effect of colony spatial organization on intracolony food distribution using laboratory and field colonies of odorous house ant. Sucrose water spiked with rabbit IgG was presented to colonies containing a single nest (monodomy) or multiple nests (polydomy), while also adjusting the quantity and location of food in relation to the colony. In lab trials, workers and queens were collected at 1h and 8h after an allotted feeding period, and analyzed using DAS-ELISA to determine the percentage of individuals testing positive for the marker. Monodomous colonies exhibited a higher percentage of positive workers (~79%) as compared to polydomous colonies. For both monodomous and polydomous colonies, a higher percentage of individuals scored positive for the IgG marker after 8h due to the increased amount of time for nestmates to spread the marker throughout the colony via trophallaxis. Queens received less sucrose water than the workers, with no queens scoring positive for the marker when food was not present in close proximity, thus hinting the possibility of a delayed feeding behavior. In turn, field colonies were presented with aliquots of IgG spiked sucrose water for a 2h period, followed by successive sampling at 2h, 8h, and 24h intervals in order to detect the level of food distribution. Nests with food in close proximity exhibited positive percentages as high as 57% after 2h, but dropped to only 5% after 24h, indicating dilution of the marker through prolonged trophallactic exchange. These effects were less profound when each nest was presented with sucrose water. Higher levels of food distribution were expressed in colonies presented with replete donors as opposed to aliquots, with positive samples as high as 57% at 2h and 32% after 24h. Results from both laboratory and field can contribute to our knowledge of food movement in urban populations of the odorous house ant, which in turn will allow for improved baiting strategies.

Degree

M.S.

Advisors

Buczkowski, Purdue University.

Subject Area

Entomology

COinS