The Asian citrus psyllid (ACP) can spread the lethal and incurable citrus disease known as huanglongbing (HLB) or citrus greening that threatens the multi-billion dollar global citrus industry. In Southern California, large and widespread populations of ACP have been detected in several counties, having arrived, most likely, from Mexico where ACP is widely established.
This is a female Tamarixia radiata, highly magnified. The tiny parasitic wasp lays eggs in Asian citrus psyllid nymphs, eventually killing them.
Credit: Jason Mottern, UC Riverside
This photo shows an Asian citrus psyllid nymph.
Credit: Mike Lewis, CISR, UC Riverside.
In 2011, for the first time entomologists at the University of California, Riverside released Tamarixia radiata, a wasp that is the natural enemy of the ACP, in a citrus grove in Riverside to help control the psyllid. But is this wasp safe to use? Does its introduction pose any risk to the environment?
Results from Federally mandated tests performed at the University of California, Riverside now show that Tamarixia radiata is indeed safe for the environment and poses no undue risk to other insects, humans or pets.
"Our work demonstrates that Tamarixia radiata is very specific to the target it is being released to kill — the nymphs of the Asian citrus psyllid in this case," said Mark Hoddle, the director of the Center for Invasive Species Research, whose lab performed the tests.
Study results appear in the February 2014 issue of the Journal of Economic Entomology.
Safety testing in biological control is important as the release of natural enemies may pose some type of environmental risk. In this instance, Tamarixia radiata were imported from the Punjab region of Pakistan, and tested for safety in quarantine at UCR over an 18 month period.
To test the safety of Tamarixia, different species of native California psyllids were exposed to the wasp in a series of tests. The tests were designed to give the wasp a "choice" between ACP and a non-target psyllid speices, or there was "no choice" (that is, the wasp was only given access to a non-target species, one it had not evolved with). When given a choice, Tamarixia overwhelming attacked ACP, the researchers found.
"In only one instance was a non-target species attacked at very low rates — less than 5 percent," Hoddle said. "This was the native pest potato psyllid, which spreads a bacterium that causes zebra chip disease. Such low attack rates are unlikely to cause population declines of this pest."
According to Hoddle, such results demonstrate that carefully selected natural enemies used in biological control programs for invasive pests can be very safe and should not cause unwanted environmental damage.
"There is growing concern over the damage that invasive species cause," he said, "and biological control programs don't want to be causing additional problems through releasing inappropriate agents for the control of invasive pests. Safety tests like those conducted in this study greatly minimize these risks."
Hoddle noted that the tests were difficult to conduct in quarantine.
"Native psyllids are hard to find and the native plants they grow on are difficult to culture in the laboratory," he said. "It was very rewarding to have completed these demanding studies over an 18 month period and to discover that the Pakistani wasp will be a good natural enemy to use in California for the biological control of ACP."
In 2011, the U.S. Department of Agriculture reviewed and approved the 60-page Environment Assessment Report, the foundational work that the research paper is based on, and approved release of Tamarixia from quarantine. The data presented in the report is essentially the same as the published paper except that this time it was reviewed by additional scientists.
"We have now released more than 200,000 Tamarixia radiata in Southern California at more than 350 different sites, mainly in urban areas and spanning six counties — Imperial, Los Angeles, Orange, Riverside, San Bernardino, and San Diego," Hoddle said. "They have established and are spreading, tracking down ACP on citrus in people's gardens and orchards."
The Tamarixia larvae will eat the ACP nymphs, killing them, and emerge as adults about 12 days later. Adult female Tamarixia also eat other ACP nymphs, killing many in the process.
Hoddle was joined in the study by Raju Pandey, a former postdoctoral researcher in his lab and working now with the Citrus Research Board.
The research was supported by a California Department of Food and Agriculture Specialty Crops Grant and a Citrus Research Board grant.
The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment has exceeded 21,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of more than $1 billion. A broadcast studio with fiber cable to the AT&T Hollywood hub is available for live or taped interviews. UCR also has ISDN for radio interviews. To learn more, call (951) UCR-NEWS.
Iqbal Pittalwala | EurekAlert!
Forest Management Yields Higher Productivity through Biodiversity
14.10.2016 | Technische Universität München
Farming with forests
23.09.2016 | University of Illinois College of Agricultural, Consumer and Environmental Sciences (ACES)
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
27.10.2016 | Materials Sciences
27.10.2016 | Physics and Astronomy
27.10.2016 | Life Sciences