Orange County Register

Orange County remains under quarantine for the Asian citrus psyllid, a tiny insect that reveals the Russian-doll intricacy of biological invasion.

Hidden in plant shipments or luggage – say on a cutting of a favorite fruit tree brought back from a trip overseas – the psyllids likely hitched a ride to Santa Ana. A bit smaller than aphids, their distant cousins, the psyllids have appeared elsewhere in Southern California, prompting other quarantines – most recently in Los Angeles County.

The insect itself is unlikely to kill the to trees, devouring leaves and stems and showing no interest in citrus fruits. But hiding within the Asian citrus psyllids might be a deadly type of bacteria.

Once transmitted to trees through the psyllid’s mouth parts, the bacteria can infect them with an incurable disease that goes by a variety of names: citrus greening disease, yellow dragon disease, huanglongbing.

In the long run, the bacteria will cause the trees to waste away and die. In the meantime, it causes enough stress to make the tree’s fruit discolored and bitter.

So far, the bacteria have not been found in Orange County or elsewhere in California. Some southeastern states, such as Florida and Louisiana, have the insect and the disease, while others have only the insect.

The quarantine means backyard citrus trees, especially their leaves, should not be moved.

Scientific name: Diaphorina citri
Sources: Orange County Entomologist Nick Nisson; California Department of Food and Agriculture.
Next week: bobcats
Photo: Courtesy CDFA

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