A newly discovered wasp can increase its own chance of survival by infecting another parasitic wasp and controlling its mind.

Credit: Andrew Forbes

The crypt gall wasp (Bassettia pallida) causes trees to produce abnormal growths, or galls, which provide a protected place for their eggs. Newly developed adult wasps gnaw their way out, but some die with their head blocking the escape hole.

To find out why, Kelly Weinersmith at Rice University in Houston, Texas, and her team collected crypt galls, and found that nearly all head-plugging wasps were infected with a previously undescribed species of wasp, the crypt-keeper (Euderus set, pictured). The team resealed some head-plugged holes, and found that E. set adults were three times more likely to die trapped in these galls than in those in which they only had to emerge through B. pallida heads. This suggests that E. set is manipulating the behaviour of its host, causing B. pallida to dig the hole in the crypt and plug it with its head, allowing E. set to escape easily, the authors say.

Proc. R. Soc. B 284, 20162365 (2017)