The bacterium responsible for citrus greening causes infected trees gives off a scent that rings the dinner bell for the disease-carrying insect, University of Florida researchers say.

This finding might distress growers, but it could enable scientists to better monitor the insect and maybe cut the chances healthy trees become infected.

The study was published online March 22 by the journal PLoS Pathogens. The article, which is open access, is at http://dx.plos.org/10.1371/journal.ppat.1002610

Greening-infected citrus trees emit a fragrant chemical called methyl salicylate, said study author Lukasz Stelinski, an assistant professor with UF’s Institute of Food and Agricultural Sciences.

Citrus trees release the same chemical, in the same amount, when under attack by the Asian citrus psyllid, the insect that transmits the bacterium.

When the pests encounter a faint whiff of methyl salicylate they interpret it to mean that other psyllids have found a good place to feed, and hurry to join the banquet. One experiment in the study showed that psyllids were more likely to land on infected citrus trees than healthy ones.

It turns out the dinner bell is a bit misleading for the psyllids, he said. Greening infections deplete trees of some nutrients psyllids need, including nitrogen and phosphorus. Another experiment in the study showed that psyllids feeding on infected trees frequently moved to healthy trees when given the opportunity.