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United States Department of Agriculture

Agricultural Research Service

Research Project: Discovery & Development of Biological Control Agents for Weeds/insect PESTS...INVASIVE in the U.S. Native to Australia & Southeast Asia
2011 Annual Report


1a.Objectives (from AD-416)
Objective 1: Discover, identify, and initiate the characterization of new biological control agents for targets, including, but not limited to, the weeds Melaleuca quinquenervia, Lygodium microphyllum, Casuarina spp., Paederia foetida, Rhodomyrtus tomentosa, Triadica sebifera and Hydrilla verticillata, and the psyllid pest, Diaphorina citri. Other weeds and insect pests that are invasive in the U.S. and native to Australia and/or Southeast Asia can become priority targets as required.

Objective 2: Conduct preliminary field and laboratory research on natural enemies to assess efficacy and host-range to determine their potential for use as biological control agents. Assess results to prioritize potential agents for introduction into the United States. Expedite establishment of high-priority agents by collecting, rearing and shipping to U.S. collaborators for high priority target weeds, such as additional agents for M. quinquenervia.

Objective 3: Conduct ecological studies on targets that identify the key regulatory factors in its native habitat and use this understanding to direct selection of agents.


1b.Approach (from AD-416)
Objective 1: Foreign exploration will be conducted in Australia and Southeast Asia for potential biological control agents of Melaleuca quinquenervia, Lygodium microphyllum, Casuarina spp., Paederia foetida, Rhodomyrtus tomentosa, Triadica sebifera and Hydrilla verticillata and additional weed targets as determined by ARS and stakeholders. Selection of search areas will be guided by the center of origin of the weed species (classical and molecular diagnostics), habitat diversity, climate matching, specific phenology and ecology of the targets, and consultation with local and foreign contacts.

Objective 2: High priority agents identified in exploration will be further evaluated in laboratory and field studies. Studies will investigate the basic biology of the organism, seasonal phenology, impact on its host, and host range. Specific aspects of an agent’s biology such as critical temperature limits will be investigated.

Objective 3: Field and laboratory studies will be conducted on target weed species which measure factors such as stand regeneration, seed production, biomass accumulation, litter fall, etc. Data will also be used to identify biological attributes that can be manipulated with biological control agents to affect control.


3.Progress Report
The gall midge Lophodiplosis indentata was the priority for research on the biological control of melaleuca, Melaleuca quinquenervia. Colonies were used to supply the IPRL quarantine facility in Gainesville. Seasonality of this insect was monitored in southeast Queensland for three years. The impact of interactions between L. indenata and the stem-galling relative L. trifida were studied. The defoliating moth Careades plana in north Queensland was collected for recolonisation attempts. Testing of the puff-ball gall former, “Sphaerococcus” ferrugineus has been suspended and will be resumed in late 2011. Cultures of the bud-weevil, Haplonyx multicolor, were destroyed when a decision was made in collaboration with IPRL colleagues to cease further evaluation of this non-specific insect.

Research is underway to survey the abundance of Lygodium stem-boring pyralid moths, Ambia sp., at different times of the year to understand seasonal fluctuations in abundance. In 2010/2011, over 700 borer damaged stems and Ambia sp. pupae were collected and shipped/hand carried to ABCL quarantine in Brisbane. An F1 generation Ambia adult was obtained in quarantine for the first time. For the first time, borers were located in Australia, attacking L. microphyllum near Bamaga on Cape York, Queensland. Larvae of the defoliating moth Lygomusotima stria were collected in Singapore, shipped to ABCL, colonised, and subsequently transhipped to IPRL. Surveys of downy rose myrtle, Rhodomyrtus tomentosa, were conducted in China. Small amounts of damage caused by larvae of the flower/fruit and tip feeding Cosmopterigidae moth Metharmostis sp. were observed in Jiangxi, Guangdong and Guangxi provinces. Larvae of other flower/fruit feeding Lepidoptera were also collected and are being reared by collaborators at the Chinese Academy of Sciences (CAS) in Wuhan, Hubei Province. Specimens of Metharmostis sp. were imported into ABCL quarantine from two sites in Hong Kong from which adults and parasites were reared for taxonomic purposes. Several shipments of Metharmostis sp. were also made to the IPRL quarantine in Gainesville, Florida where a colony has been established and host range testing has been initiated. Sites in mainland China, Hong Kong and India were evaluated for demographic studies planned to commence in late 2011.

Exploratory research continued on skunk vine, Paederia foetida, and Australian pine, Casuarina spp.; both plants are serious weeds in the United States, particularly Florida and Hawaii. Stem-boring moth larvae were collected from P. foetida in Hong Kong and shipped directly to IPRL quarantine in Fort Lauderdale. Cultures of a leaf -galling wasp, Selitrichodes sp., an undescribed leaf-galling midge, and a defoliating moth, Cryptophasa irrorata, are in culture at ABCL for evaluation as potential control agents of Casuarina spp.

Collections of parasites of the Asian citrus psyllid, Diaphorina citri, were made in Yunnan China and Singapore and shipped to APHIS quarantine in Mission Texas were quarantine cultures of the Tamarixia radiata have been established.


4.Accomplishments
1. In November 2010, the USDA ARS Australian Biological Control Laboratory (ABCL) officially moved from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) facilities at Indooroopilly, Queensland to the new EcoSciences Precinct at Dutton Park, Brisbane. This is a joint facility shared by CSIRO, who hosts ABCL through a specific cooperative agreement, with several state and federal research organisations and supports a diverse array of research that is conducted on site, including biological control. Our new ABCL laboratory utilizes a state of the art quarantine facility into which we import insects from Asia for evaluation as potential biological control agents for US weeds. ABCL also has new office, laboratory and glasshouse facilities which will improve the quality of its research.

2. Asian citrus psyllid, Diaphorina citri, is a serious insect pest and threatens the viability of the citrus industry across the United States by vectoring the devastating disease, citrus greening. Tamarixia radiata wasps were collected from sites in Yunnan Province in southern China, and from Singapore. These parasites were shipped to USDA APHIS quarantine facilities in Texas where cultures have been established alongside those from earlier collections made in 2009/2010 in Guangxi Province, Guangdong Province and Hong Kong, China. If approved, these parasites could be used to control field populations and the spread of the Asian citrus psyllid in the United States, particularly in California, Florida, and Texas

3. A new agent is under evaluation for the biological control of the melaleuca paperbark tree, Melaleuca quinquenervia, a serious weed in south Florida where it invades wetland areas. Colonisation of the gall midge, Lophodiplosis indentata, at ABCL in Brisbane led to a successful shipment to the USDA ARS Invasive Plant Research Laboratory (IPRL) quarantine in Gainesville, Florida. A sister species, L. trifida, has already been released in Florida and spread rapidly causing extensive damage to saplings. Two other released agents, a foliage-feeding weevil and a sap-sucking psyllid, discovered by staff of the USDA ARS Australian Biological Control Laboratory in Australia, have had a significant impact on this tree. The melaleuca project has been a major success in biological control as a result of collaborative research between the Australian Biological Control Laboratory in Brisbane and the USDA ARS Invasive Plant Research Laboratory in Fort Lauderdale and Gainesville, Florida.

4. Lygodium microphyllum is a serious weed in south Florida and threatens natural wetland areas such as the Florida Everglades. Stem-boring larvae of Ambia spp. moths are being evaluated as biological control agents for this fern but rearing under quarantine conditions has been problematic. New quarantine glasshouse facilities facilitated the use of actively growing L. microphyllum plants for culturing and for the first time an F1 generation adult was reared. For the first time, borers were located in Australia, attacking L. microphyllum near Bamaga on Cape York, Queensland. This will enable research on this species outside of the confines of quarantine.


Last Modified: 12/21/2014
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