Nothing in Biology Makes Sense: The vital importance of genetic variation

Black Bean Aphid Aphis fabae. Photo by robbersdog.

Over at Nothing in Biology Makes Sense!, Devin Drown describes an interaction between aphids and a species of wasp who lay their eggs in the aphids so their larvae can eat the aphids alive. A new study tests whether the success of a wasp larva infecting an aphid depends on the specific genetics of the wasp, and of a bacterial symbiont the aphid carries:

The Vorburger group studies a crop pest aphid, Aphis fabae, and its common wasp parasitoid, Lysiphlebus fabarum. The adult parasitoids lay their eggs in unsuspecting aphid hosts. As the parasitoids develop they battle the hosts defenses. Some aphid hosts are also infected with a bacterium symbiont, Hamiltonella defensa, which can provide protection against the parasitoid by releasing bacteriophages that target the parasitoid invader (Vorburger et al 2009; Vorburger and Gouskov 2011). If the wasp parasitoid can evade all the host defenses then eventually it develops inside the still living aphid. Eventually, as the authors describe in grisly detail

“metamorphosis takes place within a cocoon spun inside the host’s dried remains, forming a ‘mummy’ from which the adult wasp emerges” (Rouchet and Vorburger 2012).

To learn how Vorburger et al. evaluated the importance of wasp genetics for successfully mummifying aphids, go read the whole thing.◼