Bacteria make locust-swarm signal

A pheromone that helps drive locusts into a swarm comes from bacteria in their gut. For a locust, that urge to join the crowd may literally be a gut feeling. The pheromone guaiacol plays a role in sending swarms of desert locusts into the air. Now, an English research team has traced the compound to bacteria in the locust gut.

Tracking the guaiacol source required building an elaborate system to rear locusts in a sealed, sterile box, report Rod J. Dillon and his colleagues from the University of Bath in the Feb. 24 Nature. Putting eggs with sterilized surfaces into the germ-free setup yielded a generation of locusts with no bacteria in their guts.

The superclean locusts produced fecal pellets that smell “less medicinal” than normal locust droppings do, notes Dillon. Chemical analysis attributed the difference mainly to the lack of guaiacol. When researchers introduced one bacterial species, Pantoea agglomerans, both smell and guaiacol returned.

Gut bacteria aid plenty of creatures, people included, but Dillon says he doesn’t know of another example where a host depends on hitchhikers for this type of communications signal.