Now, in a surprising study published in the June 6 issue of Public Library of Science Biology (PLoS Biology), researchers at The Institute for Genomic Research (TIGR), the University of Arizona, and their colleagues have discovered that the sharpshooter's deprivation diet is sneakily supplemented by not one, but two co-dependent bacteria living inside its cells.
Although insect-bacteria symbiosis is common, this is the first genomic analysis of three partners. In the study, a team of scientists led by TIGR microbiologist Jonathan Eisen, now at the University of California, Davis, uncovered an intimate metabolic co-dependency among the glassy-winged sharpshooter (Homalodisca coagulata) and two bacteria, Baumannia cicadellinicola and Sulcia muelleri. The sharpshooter channels the sweets from sap to the bacteria, which in turn feed the insect vitamins, cofactors, and essential amino acids.
"Much as mosquitoes transmit malaria, the sharpshooter transmits plant disease, including Pierce's disease, which threatens vineyards," Eisen says. "In order to design methods to fight the insect, we've got to understand how it works and its weaknesses. We knew symbionts were doing something for this insect--but until this study, we had no clue what that was."
In particular, in this case, the threesome came as a surprise. Many insects, such as aphids and cicadas, feed on the sap from a plant's xylem or phloem, pipes that transport water and food within a plant. These sap-feeders are often known to rely on resident bacteria for a balanced diet especially the synthesis of the "essential" amino-acids that all animals, including humans, cannot make for themselves.
But researchers had assumed that the sh
Contact: Kathryn Brown
The Institute for Genomic Research