Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How safe is the enemy of a citrus-threatening pest?

05.02.2014
UC Riverside study shows Tamarixia radiata, a natural enemy of the Asian citrus psyllid, poses negligible environmental risk

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.

The study is the first published study designed specifically to determine the host range of Tamarixia radiata. The results are important as the wasp is being used for ACP biological control in Florida, Texas, the Caribbean, Central and South America, and Mexico.

"These types of studies continue to advance the safety of biological control for suppressing populations of invasive pests thereby greatly reducing reliance on pesticides for control," said Hoddle, a biological control specialist in the Department of Entomology. "In urban areas, initially pesticide treatments were applied to ACP-infested trees, and chemically-treated buffer zones were established around sites to control the pest."

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!
Further information:
http://www.ucr.edu

More articles from Agricultural and Forestry Science:

nachricht Fighting a destructive crop disease with mathematics
21.06.2017 | University of Cambridge

nachricht Unusual soybean coloration sheds a light on gene silencing
20.06.2017 | University of Illinois College of Agricultural, Consumer and Environmental Sciences

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>