Foreign Herbivores May Be Key to Curbing Invasive Weeds

Joint research with scientists in Argentina, Australia and China could lead to discovery of new biological control agents for several exotic weeds plaguing Florida and other U.S. states. Some of the worst offenders are hydrilla, Brazilian pepper, Chinese tallow and Australian pine. These and other aggressive invasive weeds occupy diverse habitats and cause many environmental problems, especially a decrease in biodiversity within infested areas.

Entomologist Greg Wheeler and colleagues at the Agricultural Research Service (ARS) Invasive Plant Research Laboratory in Fort Lauderdale, Fla., have been focusing on this growing problem in the United States. ARS is the U.S. Department of Agriculture's chief scientific research agency.

The Fort Lauderdale scientists have been collaborating with counterparts at the ARS South American Biological Control Laboratory in Hurlingham, Argentina, and the ARS Australian Biological Control Laboratory in Indooroopilly, Australia, as well as with China's Academy of Science.

Together, the researchers are conducting extensive field surveys to discover herbivorous insects and mites that feed on the invasive weeds in their native ranges. The researchers have recovered many promising new candidate biological control agents, including weevil, thrip, psyllid, moth and mite species. Several are undergoing—or have completed—preliminary testing to determine their safety for U.S. release.

One, the aquatic moth Paracymoriza vagalis, is a promising hydrilla biological control agent from Indonesia. Protected from predators in dense plant material, the moth's larvae can survive submersion for extended periods while feeding on the weed's underwater portions.

Other potential biocontrols include a South American weevil, Omolabus piceus, which may be effective against Brazilian pepper, and a possibly safe and host-specific insect, a leaf-rolling weevil called Apoderus bicallosicollis, which consumes vast quantities of Chinese tallow leaves.

Wheeler has been invited to report these biological control findings at the SICONBIOL (Brazilian Society for Biocontrol) in Brasilia, Brazil, June 30-July 4. This year's symposium theme, "Innovate to Preserve Life," will focus on the development and application of new biological control technologies and strategies, especially on progress being made in demonstrating the outstanding potential of certain herbivorous candidates.