Two "New" Moths May Thwart Troublesome Weeds

Two recently discovered moth species show promise for helping keep a pair of emerging invasive weeds in check.

One of the small moths Agricultural Research Service (ARS) entomologist John W. Brown helped find—a new species of Dichrorampha—is seen as a possible biological control agent for Chromolaena odorata, a plant known as Siam weed, among other names. It ranks among the world's worst invasive weeds.

Originally from Central and South America, C. odorata is now found in Southeast Asia, Africa and many Pacific islands, where it impacts land used for forestry, pasture and crops such as rubber, coffee, coconut, cocoa and cashew.

Brown, who is with the ARS Systematic Entomology Laboratory (SEL) in Washington, D.C., worked with Costas Zachariades, an entomologist with South Africa's Agricultural Research Council 's Plant Protection Research Institute, to identify and characterize the new Dichrorampha species.

The other moth Brown helped discover—Cochylis campuloclinium—attacks Campuloclinium macrocephalum, a plant commonly known as pompom weed that's become particularly troublesome in South Africa. Originally from Central America, pompom weed displaces native pasture vegetation in grasslands and wetlands.

According to Brown, the two findings are potentially important because caterpillars of many species of small moths serve as excellent biological control agents for invasive weeds. By feeding on weeds' flowers or other reproductive parts, they provide an alternative to herbicides and costly mechanical removal.

Each year, SEL scientists in Beltsville, Md., and Washington, D.C., identify and classify more than 60,000 specimens of insects and mites that can impact U.S. agriculture and security. Many of these samples are sent from outside the United States.

Specimens of the new Dichrorampha species—which was first described and illustrated from Jamaica—were sent to SEL by Zachariades. C. campuloclinium was first described from Argentinean samples.

A litmus test for measuring both moths as biological control agents will be the extent of the exclusivity with which they feed on their intended targets, according to Brown.

ARS is the U.S. Department of Agriculture's chief scientific research agency.