Worker insects spend their existence tending to the every need of their queens—even giving up their sex lives. But why are queens the only ones allowed to reproduce? The answer lies in pheromones—chemical signals, produced by queens, which workers react to. To further investigate the means behind this reproductive control, researchers looked at the chemicals produced by the queens of three social insects: the buff-tailed bumblebee, the common wasp (pictured), and the desert ant. Once identified, the scientists tested the potential pheromones on isolated workers to see if they prevented reproduction. In all three species, similarly structured alkanes (a type of carbon-based compound) limited the development of the workers’ ovaries , the researchers report online today in Science. In addition, a review of existing studies revealed that alkanes are the most common chemicals overproduced by queens across a wide variety of social insect species. By constructing an evolutionary history, the researchers determined that these pheromones likely date back at least 145 million years, to these insects’ common (and solitary) ancestors—who probably used the chemicals as fertility signals to attract males. Over time, these signals may have developed into a simple communication system, with daughters temporarily giving up reproduction to assist their mothers when the latter were fertile (thereby helping to indirectly pass their genes to the next generation). The researchers believe these signals may have paved the way for subsequent evolution of complex, colonial behaviors seen today among these varied insect groups.
ScienceShot: The Queen of Sex