Insect Immune Suppression

Drosophila Flies

Of the hundreds of thousands of described insect species, over 10 percent of the total are parasitoids. Parasitoids are insects that lay their eggs inside another insect. The parasitoid larvae feed on the host tissues. Many insects have defenses against parasitoids including immune systems that attack parasitoids. Insect immune cells are concentrated in their blood (the hemolymph). The immune cells must detect the parasitoid before the parasitoid can be attacked. Successful parasitoids often suppress the immune system of the host.

Drosophila flies, a model for the study of genetics, are susceptible to parasitoids. Drosophila immune cells can recognize and attack parasitoid eggs. When an immune cell recognizes a parasitoid or other foreign invader, the cell releases calcium as a signal to initiate its attack. Parasitoid wasps in the genus Ganaspis contain a venom that blocks the calcium signal. This blocks the ability of Drosophila immune cells to attack Ganaspis eggs. Characterization of immune suppression factors in parasitoids are important tools for learning more about insect immunity systems, knowledge that may be applicable to immune systems in general.

For More Information:
Nathan T. Mortimer, Jeremy Goecks, Balint Z. Kacsoh, James A. Mobley, Gregory J. Bowersock, James Taylor and Todd A. Schlenke. 2013. Parasitoid wasp venom SERCA regulates Drosophila calcium levels and inhibits cellular immunity

PNAS June 4, 2013 vol. 110 no. 23 9427-9432
doi: 10.1073/pnas.1222351110