Looking at alternative approaches to pest control

In response to the devastating huanglongbing disease sweeping through California’s citrus orchards, researchers are testing a biological control program. They are using two wasps from Asia that are natural enemies of the Asian citrus psyllid (Diaphorina citri), an invasive species of insect that spreads the bacteria responsible for the disease.

The study was supported by the University of California Riverside. Its results were published in the journal California Agriculture.

  • Huanglongbing – also known as citrus greening disease – is caused by the bacterium Candidatus Liberibacter asiaticus. Very deadly to profitable citrus plants, its primary vector is the Asian citrus psyllid, a jumping bug from southern Asia that has spread across the world.
  • The citrus industry in California has tried to reduce or exterminate psyllid populations using chemical pesticides. However, these campaigns were expensive and could only target limited areas, so they were eventually discontinued.
  • Researchers looked for natural enemies of the psyllid in its homeland. They settled upon Tamarixia radiata and Diaphorencyrtus aligarhensis, two tiny wasps that act as parasitoids for the psyllid.
  • After determining that these wasps would only attack the Asian citrus psyllid, populations of both species were reared and released in urban southern California. Surveys checked on their release areas over the next few years to determine if they had spread out.
  • T. radiata was confirmed to have established itself in California. The wasp was confirmed to be effective against its intended target. D. aligarhensis is still establishing itself but also appears to be having an effect on psyllid populations.

The researchers surmise that this biological approach to curbing Asian citrus psyllid populations could supplement other means of controlling the spread of huanglongbing.

Browse the full version of the study at this site. You can get more stories about natural means of pest control at Ecology.news.

Journal Reference:

Milosavljevi? I, Schall K, Hoddle C, Morgan D, Hoddle M. BIOCONTROL PROGRAM TARGETS ASIAN CITRUS PSYLLID IN CALIFORNIAS URBAN AREAS. California Agriculture. 13 September 2017;71(3):169–177. DOI: 10.3733/ca.2017a0027.

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