Ants have an uncanny ability to find a picnic. One minute your plate of food is fine, the next, ants have descended and are attempting to make off with some bread and cheese. Worker ants are frequently the culprits. In ant societies, worker ants are the female ants that never reproduce, and instead forage for food, care for the queen’s offspring, and protect the community. Worker ants take on different roles during their lifespan; young worker ants typically complete tasks inside the nest, whereas older workers venture outside.
Transitioning from work inside to outside the nest is a big deal for ants as they are exposed to new environmental challenges. The changing temperature and humidity levels can wreak havoc on the ant’s water levels and can potentially dry them out. Researchers have shown that worker ants have a strategy to protect themselves that depends on compounds called cuticular hydrocarbons (CHC). These compounds protect the ants from drying out by forming a protective layer on their surface. Before an ant moves from working inside the nest to outside, they increase the amounts of these hydrocarbons on their surface of their body. We know that CHC levels increase to protect ants during this transition to outdoor work, but we don’t yet understand the molecular details of how CHC production is controlled.
In this study, a group of researchers examined whether a particular invertebrate hormone, inotocin, was important for increasing CHC amounts. Inotocin is interesting because it is like what would happen if the two common hormones oxytocin and vasopressin were combined. As such, just like oxytocin and vasopressin, inotocin plays an important role in social behaviours. They began their study by measuring inotocin levels in ants with different jobs (i.e. queens, males, and workers). They found that worker ants, specifically the foragers, had more inotocin than the queens. They then dove deeper to identify the cells that produce inotocin. They discovered that the special cell type that produced the inotocin receptor (the dock that allows a cell to respond to inotocin specifically) also produced CHC.
This study provides exciting insight not only into CHC, but also into the previously poorly understood insect hormone, inotocin. The study suggests that inotocin is an important regulator of CHC production. Interestingly, there are other types of insects such as honeybees that have CHCs on their surface, but do not rely on inotocin signaling. The next step will be to determine how different insects control CHC production. By comparing inotocin-dependent and -independent insects, researchers may get a better understanding of the role inotocin plays in insect health.
Summary written by: Emma Finlayson-Trick
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Oxytocin/vasopressin-like peptide inotocin regulates cuticular hydrocarbon synthesis and water balancing in ants