Center for Plant Health Science and Technology
Biological Control Program
Location: 1730 Varsity Dr., Suite 400,
Raleigh, NC 27606
Phone: (919) 855-7407
Fax: (919) 855-7480
Contact: Ken Bloem
The CPHST Biological Control Program is a virtual team of scientists (14-18 depending on project approvals from year to year) located at various CPHST locations. The program focuses on developing technologies that support the safe use of parasitoids, predators, herbivores, and pathogens to help mitigate the impacts of introduced invasive weeds and plant pests, while minimizing impacts on the environment and non-target organisms.
CPHST scientists provide technical oversight and expertise to programs to ensure that scientific knowledge gaps are identified and addressed, cooperators deliver needed services, and implementation protocols and educational materials are effectively developed and transferred to stakeholders as quickly as possible. More specifically they provide permitted biocontrol agents collected from established field insectaries for distribution by PPQ and other project cooperators, develop new rearing and monitoring systems, and work to ensure the safety of biocontrol agents by conducting both pre- and post-release impact studies. Project selection is based on national review recommendations from stakeholders within PPQ as well as the National Plant Board.
CPHST Fort Collins continued to assess the white rust pathogen Pustula spinulosa (formerly Albugo tragopogonis) from China as a potential biological control agent for Canada thistle. Field observations suggest that the Chinese Pustula spinulosa could be highly specific and damaging to this weed.
Diffuse and Spotted Knapweed
Cyphocleonus achetes is a weevil introduced into North America for the biological control of diffuse and spotted knapweed. CPHST developed a rearing system based on artificial diet and successfully reared the weevil for 16 generations. With the help of cooperators at the Nez Perce Bio-Control Center, we were able to confirm that diet-reared insects from releases in 2010 and 2011 successfully established in the field and the technology was transferred to the Center.
Rush Skeleton Weed
CPHST tested artificial diets for rearing Bradyrrhoa gilveola (pyralid moth), which is an agent for biological control of rush skeleton weed, Chondrilla juncea. Four different diets were tested: rice stem borer diet, pink bollworm diet, cactus moth diet and the Hylobius diet developed by CPHST. The longest survival rates were obtained on the Hylobius diet.
The Russian knapweed gall midge, Jaapiella ivannikovi, was permitted for U.S. release in 2009. A greenhouse-based rearing program for J. ivannikovi was initiated at Fort Collins in 2011 and continued in 2012. In 2012, nearly 1600 J. ivannikovi galls were provided for field release at 38 sites in 8 states: California, Colorado, Idaho, New Mexico, Oregon, Utah, Washington, and Wyoming. To date, project partners have released J. ivannikovi at 57 sites in the eight states mentioned above.
CPHST Fort Collins successfully continued a greenhouse-based rearing program for the yellow toadflax stem-mining weevil, Mecinus janthinus, to optimize rearing. PPQ partners in Montana provided field-collected M. janthinus for release in Colorado, Idaho, North Dakota, Oregon, South Dakota, Washington, and Wyoming in 2012.
Asian Citrus Psyllid
From September 2011 through September 2012, over 120,000 Tamarixia radiata parasitoids were mass-produced and released by the CPHST Mission Laboratory in the Lower Rio Grande Valley (LRGV) of Texas for ACP management. Both open and closed releases continue and are being used to assess establishment and efficacy of the parasitoids. Releases in the urban environment are being made in collaboration with Master Gardeners, Texas A&M Agrilife Extension, and Texas Citrus Mutual using field insectary cages in RV parks to help augment parasitoid release numbers. Recovery of parasitoids has been confirmed at 39 locations (17 inside the HLB quarantined zone and 22 outside). Closed cage releases made in fine-mesh sleeve cages indicate average parasitism levels of 10.4%. Host feeding studies indicate additional mortality at 64.9%. Using the field cage rearing methods developed by the Mission Laboratory, the CPHST California Station initiated a cooperative effort together with the Citrus Research Board, CDFA and University of California to develop field cage mass-rearing techniques for T. radiata in California.
Emerald Ash Borer
Methods to determine the establishment, spread, and parasitism levels of EAB parasitoids, were developed in Michigan with cooperators. These methods included protocols for use of yellow pan traps and tree sampling, as well as methods to assess ash stand health, such as transect survey protocols for monitoring ash regrowth. These methods are now being shared with and transferred to cooperators in other states. CPHST Otis also conducted host specificity tests for a new Spathius species from Russia. A permit application for field release was recently submitted. The new species from Russia may be more cold tolerant than S. agrili from China, which was collected from a considerably warmer climate.
CPHST Phoenix in cooperation with ARS finished the early season exposure persistence tests with the fungal pathogen Metarhizium acridum for grasshopper control and will use the data to respond to public comments on the environmental assessment for the release of the commercial Australian and African strains for small plot tests. Trials have indicated that the pathogen persists, but remains below levels that would be expected to produce infections in native populations. If a finding of no significant impact is issued based on the data collected, small field trials will be conducted as soon as practical.
Harrisia Cactus Mealybug (HCM)
HCM (Hypogeococcus pungens) is a severe pest of columnar cacti worldwide and is a major threat to endangered endemic cacti in Puerto Rico and the ornamental industry in the mainland U.S. Working with cooperators in Puerto Rico, the CPHST Mission Lab identified two endemic parasitoids that attack HCM. Genetic comparison of the most prevalent parasitoid species, Leptomastidea sp., indicates that it is identical to populations attacking HCM in Barbados and Florida.
Red Bay Ambrosia Beetle
The red bay ambrosia beetle, Xyleborus glabratus, is the vector of laurel wilt disease that has caused widespread and almost complete mortality of bay and avocado trees in infested areas. CPHST Miami collaboratively developed with University of Florida scientists a method using sentinel logs infested with the beetle to collect potential natural enemies attacking them. Multiple families from the order Hymenoptera (Scelionidae, Braconidae and Eulophidae) emerged from trees infested with X. glabratus and other Scolytinae. According to the literature, species in these families have been identified as parasitoids of Scolytinae and efforts are now underway to confirm host associations.
FY 2012 was the final year of the Sirex biological control project using Australian nematodes. The last controlled releases of the imported Kamona strain of Beddingia siricidicola were made in September 2012 in four red pine plantations in Pennsylvania. Releases in the previous season compared infection rates when girdled trap trees were inoculated at three times in the season. Altogether the Otis Lab undertook controlled releases over seven seasons in this project and collected DNA samples from infected wasps over five years. The latter samples are being analyzed to discriminate the Kamona and “native” North American strains. When complete, these analyses will provide a good picture of the relative effectiveness of the two nematodes.
Tuta absoluta is a devastating pest of tomato. Efforts are currently underway, in cooperation with researchers from Instituto Valenciano de Investigaciones Agrarias in Valencia, Spain, to assess the local native enemy community in Florida and test for their potential to control T. absoluta. In Spain, integrated pest management practices using generalist natural enemies now largely control the pest.
Imported Fire Ant
Since 2002, two to three species of Pseudacteon sp. flies have been released at multiple sites in all imported fire ant quarantined states in the contiguous southeastern states and Puerto Rico. Field releases with a fourth species, P. cultellatus, began in 2011. From 2002 through 2012 there have been 138 field releases in IFA quarantined states in the contiguous southeastern states and Puerto Rico (no releases in NM and only one species released in CA) and more than 1.5 million flies have been released. Through APHIS releases, along with other federal and university releases, P. tricuspis is well established in the southern areas of the IFA regulated area covering over 50% of the IFA regulated area. The second species, P. curvatus, is well established in all southern IFA regulated states and PR, covering about 65% of the regulated area. Overwinter establishment of P. obtusus has been confirmed with very limited expansion at this time, and overwintering of P. cultellatus has not yet been confirmed.