About 300 of these minute parasitic wasps were released into a Riverside, Calif., citrus grove to help battle Asian citrus psyllid.
About 300 of these minute parasitic wasps were released into a Riverside, Calif., citrus grove to help battle Asian citrus psyllid.

University of California-Riverside entomologist Mark Hoddle released a second natural enemy of Asian citrus psyllid Dec. 16 in the same citrus grove where he released the first one.

The latest biological control agent — a minute wasp that goes by the scientific name of Diaphorencyrtus aligarhensis — was collected from the Punjab region of Pakistan, according to a news release.

The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service conducted an environmental assessment of releasing the imported wasps in the U.S. and found no significant impact, according to a Dec. 12 Federal Register notice.

Hoddle introduced about 300 wasps into a 7.5-acre citrus grove near the UC-Riverside Botanic Gardens.

The new wasp differs from the Tamarixia wasp. already approved for release. The newcomer prefers immature psyllids, or nymphs, whereas Tamarixia favors older nymphs.

Adult female wasps lay eggs inside immature psyllids. When the eggs hatch, the larvae feed on the nymphs.

The release plan calls for the new species to be introduced initially in urban parts of Southern California with psyllid infestations but where Tamarixia has not been released.