Asian Citrus Psyllid Distribution and Management
University of California
Asian Citrus Psyllid Distribution and Management

Biological Control

Tamarixia wasp parasite.  Photo: M. Lewis
Tamarixia wasp parasite. Photo: M. Lewis
The Asian citrus psyllid is attacked by many natural enemies, including lady beetles, lacewing larvae, syrphid larvae, minute pirate bugs, parasitic wasps, spiders, and birds. These natural enemies do not eradicate the psyllid, but they help reduce psyllid populations, which in turn will helps to slow the spread of HLB. Therefore, biological control is viewed as an important part of managing ACP and HLB in California, especially in areas where pesticide sprays are not possible.

One of the most promising biological control agents is the parasitoid wasp, Tamarixia radiata. This tiny stingless wasp, which poses no threat to people, lays an egg underneath the ACP nymph, which then hatches, feeds on and kills the nymph. It is easy to find evidence of this parasitoid at work because it leaves behind what looks like a hollowed-out ACP nymphal shell, known as a “mummy”.  The mummy has an exit hole where the adult parasite chewed its way out. Tamarixia and general predators have reduced psyllid populations in southern California, however not enough to prevent disease spread.  

Parasitized ACP nymphs. Photo: M. Hoddle

Since late 2011, this beneficial wasp has been mass-reared in an insectary and released into urban and suburban areas of Southern California (see video) by the California Department of Food and Agriculture. To date more than ten million wasps have been released throughout southern California at residential sites.  

You can look at the map (Map of Psyllids, HLB and Parasites) which shows the areas where Tamarixia and Diaphorencyrtis wasps have been released in southern California (data provided by CDFA). 

ANT Control to protect natural enemies is critical!

Ants climb citrus and feed on the honeydew that is stored in the white tubules that the ACP nymphs produce.  While doing that, they aggressively protect psyllids from natural enemies.   If you live in or near an area where Tamarixia has been released, then protect these natural enemies by controlling ants. See the UCIPM pest note on ants for information about how to identify and manage ants.  

Argentine ant feeding on honeydew produced by the nymph
Argentine ant feeding on honeydew produced by the nymph

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