Location: Invasive Plant Research Laboratory2012 Annual Report
1a. Objectives (from AD-416):
1. As new high-priority invasive species are detected in the U.S., conduct feasibility studies to determine their suitability for biological control. 2. Elucidate the ecology and population dynamics of targeted weeds and their potential insect and pathogen biological control agents, and investigate the impact of weed suppression on community and ecosystem structure and function. 3. Conduct faunistic and floristic inventories to discover natural enemies that may serve as biological control agents for target weeds including, but not limited to Brazilian pepper, lygodium, downy rose myrtle, skunk vine and Chinese tallow. Additional biological control agents will be sought for species for which some control has been achieved, including melaleuca. 4. Conduct risk analysis to determine environmental safety of new and existing potential biological control agents for weeds such as air potato, melaleuca, Brazilian pepper, lygodium, downy rose myrtle, Chinese tallow, waterlettuce and skunk vine. 5. Release, establish, evaluate efficacy, and corroborate environmental safety of approved biological control agents and develop and distribute the technology to customers in order to expedite their adoption and deployment.
1b. Approach (from AD-416):
Survey foreign nations for potential biological control agents, determine host specificity of candidate species, release approved agents into natural and agricultural ecosystems, and evaluate influence of agents on target weed and nontarget species population dynamics. Study molecular genetic target weeds. Study their roles as insect feeding attractants/deterrents, effects on biological control agents' nutritional and reproductive physiology, and possible use in host specificity protocols. Study biological control agents' impact on competition between target weeds and non-target native plants. Identify ways to incorporate biological control agents into IPM strategies. Survey water bodies in Connecticut for presence of troublesome aquatic weeds.
3. Progress Report:
About 10% of adult Lilioceris cheni released in Florida for the first time during November 2011 successfully overwintered and produced progeny in spring 2012. Seven sites have been inoculated this year, with a total of about 1000 individuals placed in the field. Monitoring of field sites confirms the beetles are establishing persistent populations. Long-term monitoring Melaleuca quenquinervia plots show that plant health declines and mortality increases as biological control stresses increase, and that native plant biodiversity increases. Several thousand Austromusotima camptozonale moth larvae were released on Lygodium microphyllum in caged study plots at two sites and are now being monitored for establishment. Host range trials with Lygomusotima stria are suggesting that this Lygodium moth is a host specialist suitable for release in Florida. Host range testing of the plant feeding mite Aceria neopaederiae showed that of 29 plant species tested, only Paederia foetida (the target weed) and Paederia bojeriana were suitable hosts for the mite. Host range testing with herbivores of Downy rose myrtle (Rhodomyrtus tomentosa) showed that the moth Metharmostis sp. is not a specialist and so not suitable for release. Testing of Neostauropus alternus and Carea veripes on this weed continues. Field release and monitoring of Megamelus scutellaris (from Argentina) on waterhyacinth (Eichhornia crassipes) continued, and host trials were initiated with Eccritotarsus catarinensis (South American by way of South Africa) and a Paraguayan biotype of M. sculellaris that might be better adapted to warmer climates like southern Florida. Host range trials with Brazilian pepper (Schinus terebinthifolius) herbivores showed that several moths (Leurocephala sp., Eucosmophora sp., and Oospila pallidaria) were unsuitable for use as biological controls of this weed. Trials continue with Crasimorpha infuscata (a stem galling moth), a second Crasimorpha species, and Allorhogas n.sp. (a stem galling wasp). Studies also continued with the thrips Pseudophilothrips ichini. Host trials with the Chinese tallow flea beetle (Bikasha collaris) produced only minor use of a few non-host plants including Neoshirakia japonicum, Ricinus communis (castorbean), Hippomane mancinella (Manchineel), and Gymnanthes lucida (oysterwood). Such a narrow host range is likely to meet requirements of release approval.
1. First biocontrol agent released and established against air potato in Florida. Researchers at the ARS Invasive Plant Research Laboratory (IPRL) in Fort Lauderdale, Florida, are tasked with locating, vetting the host fidelity of, implementing, and assessing the efficacy of highly specific natural enemies for use against troublesome weeds that have invaded agricultural or conservation lands. In November 2011, IPRL scientists made the first releases of an Asian leaf beetle (Lilioceris cheni) as a biological control of the invasive air potato vine (Dioscorea bulbifera) in Florida. About 10% of beetles released into cages at a local field site were still present in March 2012; by August this nascent population had greatly expanded, having produced at least three generations of progeny. An additional five sites have been inoculated with the air potato beetle, with at least one showing clear signs of L. cheni population establishment and expansion. Air potato infestations cover fences, climb over trees and shrubs, and can produce a thick canopy reminiscent of kudzu, shading out and killing native vegetation. Release and establishment of Lilioceris cheni promises to help reduce deleterious impacts of air potato on conservation lands and permit recovery of native species excluded by this weed in the U.S. Gulf Coast, and especially Florida where it occurs in 34 counties including many within the historic boundaries of Florida’s unique Everglades ecosystem.
Cuda, J.P., Christ, L.R., Manrique, V., Overholt, W.A., Wheeler, G.S., Williams, D.A. 2011. Role of molecular genetics in identifying ‘fine tuned’ natural enemies of the invasive Brazilian peppertree, Schinus terebinthifolius. Biocontrol. DOI: 10.1007/s10526-011-9418-y.