A female parasitic wasp inserts her ovipositor into a Drosophila larva to lay her egg.MICHAEL MARTIN, REED COLLEGE. COURTESY: NATIONAL SCIENCE FOUNDATIONA strain of the symbiotic Spiroplasma bacteria protects its host fly by producing a toxin that attacks the ribosomes of parasitic wasps, researchers reported July 6 in PLOS Pathogens. The study builds on the finding that another Spiroplasma strain defends against parasitic nematodes in the same way.
Spiroplasma bacteria are thought to live in at least 7 percent of insects, where they are passed down from mother to young, write the researchers in their report. In the lab, Spiroplasma-infected Drosophila have proven more resistant than their uninfected counterparts to pests such as parasitic wasps, which lay eggs in Drosophila larvae.
Until recently, scientists had few clues as to how the bacterial protection worked. Then, in 2013, a research group led by Steve Perlman of the University of Victoria found that Spiroplasma in one Drosophila species make a ribosome-inactivating protein that is toxic to would-be parasitic nematodes. Other known ribosome-inactivating proteins, fittingly abbreviated as RIPs, include the deadly ricin made famous by Breaking Bad and the Shiga toxin deployed by pathogenic E. coli ...
