Students Share Research Findings at Asian Citrus Psyllid Symposium

visitor examines poster board of research

More than 20 students made presentations at the 3rd Annual Asian Citrus Psyllid Student Research Symposium.

The Asian Citrus Psyllid is a sap-sucking insect that can carry a disease called Huanglongbing that causes citrus fruit to prematurely drop and is 100 percent fatal to citrus trees. The disease is difficult to diagnose because it can take years for infected trees to develop symptoms and looks like a nutritional deficiency.

Industry groups and state and federal agencies helped fund the students’ research because Huanglongbing (HLB) has devastated the Florida citrus industry and threatens Californian citrus. The students were trained in research methods, including data collection, experimental design, and data analysis.

“They got to research a real-world problem and get real-world experience,” says Anna Soper, a lecturer and research director for the Department of Plant Science, of the students.

HLB has caused more than $4 billion in lost revenue in Florida’s citrus industry and cost more than 6,600 jobs in orange juice production.

What’s more, the amount of acreage bearing fruit in Florida has declined 32 percent since HLB was first discovered there in 2005, says Leah Shubin, a student who researched the disease’s economic impact. The yield per acre has declined by nearly one-third, while the price per box has nearly tripled, she says.

Frozen concentrated orange juice production also has declined by 7 percent, Shubin says.

“These oranges, their quality isn’t as high as it was before the disease,” she says.

The psyllid was discovered in California in 2012 and poses a threat to the state’s $2 billion citrus industry, which provides 80 percent of the fresh citrus in the United States. Complicating matters are that 50 to 70 percent of California homes have citrus trees in their backyards.

However, most Californians seem unaware of the Asian Citrus Psyllid and HLB, according to the students’ research.

Ashley Van Vliet researched public awareness of the disease and the insect, surveying more than 1,000 people at the Cal Poly Pomona Pumpkin Festival.

“Eighty-eight percent did not know about HLB,” she says. “Eighty-two percent didn’t know about the Asian Citrus Psyllid.”

Public outreach and educational efforts have been limited, Van Vliet pointed out.

To counter the psyllid, state agricultural officials have released more than 3 million Tamarixia radiata wasps that lay their eggs on the psyllid. When the eggs hatch, the psyllid dies.

Much of the research that the students conducted centered around the psyllid or the wasps. The research included:

  • studying various techniques for growing curry leaf plants to feed the psyllid and the effect they had on the insects
  • whether adding olfactory components would make psyllid trapping systems more effective
  • examining the effect different diets would have on the wasps’ fertility and longevity
  • and how best to store the pupal form of the wasps.

The symposium was held June 2 at AGRIscapes.

The research and event were funded by the California State University Agricultural Research Institute, the California Citrus Research Board, the U.S. Department of Agriculture, and the California Department of Food & Agriculture.

The College of Agriculture has received more than $500,000 in funding for the research, which has also led to the construction of an on-campus greenhouse dedicated to raising mass quantities of the wasps.

A dozen students have gone on to graduate school, with five continuing to participate in Asian Citrus Psyllid-specific projects.

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