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ViewAttendees 21

MUVE

Student Competition 10-Minute Paper

Grad 10-min: MUVE, Hymenopera, Spiders

Polygyne ants are not cooperating: Colony boundaries and larval discrimination in multiple-queen colonies of the red imported fire ant (Solenopsis invicta)

On-Demand
Student Competition On-Demand
Unicoloniality, or the absence of behavioral boundaries between nests, is thought to promote ant invasions due to reduced intraspecific competition. The red imported fire ant (Solenopsis invicta; hereafter fire ant) occurs in two social forms: monogyne (i.e., colonies with a single egg-laying queen) and polygyne (i.e., colonies with multiple egg-laying queens). Introduced populations of polygyne fire ants are commonly referred to as unicolonial, but cooperation between and within mounds is poorly documented. If polygyne fire ants are unicolonial, mounds should freely share workers/ resources with each other, and workers should indiscriminately care for all brood within the nest. To delimit boundaries between mounds, we quantified the exchange of a carbohydrate resource labeled with an isotope tracer and correlated this exchange with colony genetic structure in the field. We also conducted an experiment quantifying within-colony conflict between workers and larvae using close siblings (i.e., from the same natal colony) and non-siblings (i.e., from a different colony). Counter to our expectations, polygyne colonies did not exchange resources or workers, indicating distinct colony boundaries. Polygyne workers also preferentially fed larval nestmates and may have preferentially cannibalized non-nestmates. Polygyne colony behavior was correlated with higher levels of within-mound relatedness between workers in the field than those previously reported in North America (mean ± SE: 0.269 ± 0.037). Our results suggest that polygyne fire ant colonies are actually multicolonial and may engage in high levels of intraspecific competition. Our study questions the assumption that unicoloniality is a key factor to ant invasions.