(2nd Place) Using axenic and gnotobiotic insects to examine the role of different microbes on the development and reproduction of the kissing bug Rhodnius prolixus

Kissing bugs are obligately and exclusively blood feeding insects. Vertebrate blood is thought to be deficient in B vitamins. Hematophagous arthropods rely on bacterial symbionts to provision these essential nutrients. Rhodococcus rhodnii, a Gram-positive actinobacteria, was originally identified in the lumen of the gut of Rhodnius prolixus and was characterized as the sole symbiont present. Recent studies have demonstrated that the kissing bug microbiome doesn’t always contain R. rhodnii or is in high abundance. We investigated if R. rhodnii or other bacteria could function as sole symbionts in R. prolixus. To ask this question we produced axenic insects or insects infected with a singular bacteria species. Insects infected with R. rhodnii alone develop faster, have higher survival, and produce more eggs than insects infected with other bacterial species. R. rhodnii grows to higher titer in the gut and persisted in the gut while other tested species were found at a lower abundance and were eventually cleared from the insect. Rhodococcus species tested had nearly identical B vitamin biosynthesis genes suggesting that while B vitamin synthesis is likely important in this symbiotic relationship it is not the sole determining factor of a symbiont in R. prolixus.