Title: Understanding the role of small non-coding RNA in bumble bee reproduction

Name: Anna Figgins
Mentor: Karen Kapheim

Certain species of ants, bees, and wasps have some of the most sophisticated forms of cooperative behavior known throughout the animal kingdom. These eusocial insects live in large family groups made up of castes (e.g., queens and workers) that specialize on different tasks within a colony. In many species, division of labor between queens and workers is associated with behavioral and physiological traits such as dominance interactions, ovary maturation, and lipid stores. Remarkably, these large phenotypic differences between castes emerge from a shared genome. This suggests caste differences stem from changes in how shared genes are regulated. We have been investigating the role of a small regulatory molecule (microRNA miR-13b) as a potential regulator of division of labor in bumble bees (Bombus impatiens). We tested the hypothesis that miR-13b regulates division of labor by inhibiting its function using small-interfering RNA (siRNA). We inhibited miR-13b function by injecting a synthetic antagonist of miR-13b (antagomir) into the abdomens of live bees. The average expression of miR-13b in the fat body of bees that received the antagomir injection was 0.52 relative to those that received the control injection (n = 7). This inhibition of miR-13b expression was accompanied by a significant decrease in fat body size. However, the influence of the antagomir only lasted 1 day. Future experiments will determine if the antagomir can influence gene expression longer than 1 day and assess physiological and behavioral changes in B. impatiens after miR-13b is inhibited. Knowledge gained from this study allows us to understand more about the mechanisms underlying social behavior in bees and helps us investigate how behavior is regulated by gene expression.