Nursing foragers and worker queens: Behavioral plasticity in the little fire ant Wasmannia auropunctata

Many social insects demonstrate behavioral plasticity where individuals can perform tasks that are not typical to a certain caste. The little fire ant Wasmannia auropunctata demonstrates age related division of labor where younger workers perform tasks in the nest and older workers forage. Queens of this ant only lay eggs. In this study we proposed to determine behavioral plasticity of queens and workers of this ant. Colonies were sampled from the field and kept in the lab in a controlled environment. To determine behavioral plasticity of workers and queens we performed different worker removal experiments. To evaluate forager plasticity, nurses were removed from nests and behaviors were observed over a period of six days. In a second experiment nurses were removed and foragers were observed for six days. To determine queen plasticity we performed three experiments. In the first we removed foragers, in the second only nurses and in the third we sequentially removed 25% of the worker population until it reached zero. Little fire ant foragers demonstrate plasticity by performing nursing duties. Contrastingly nurses do not forage precociously and continue performing there typical tasks in absence of foragers. Queens exhibit behavioral plasticity, performing nursing duties when these were absent and when colony population decreased. These findings are an important contribution to our understanding of social insect behavior and may help explain the success of this worldwide invasive species.