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Seductive Beetle Dines on Fruit Weed

A fruit-bearing weed is encroaching on some 1.5 million acres of pasture, crop and urban land in the southeastern United States. Cattle, deer and other wildlife enjoy snacking on the fruit produced by the tropical soda apple (TSA). But this weed proliferates when its seeds pass through the animals’ digestive tracts and are deposited as the animals browse. Soon after, TSA takes over precious farmland.

Agricultural Research Service scientists led by Daniel Gandolfo with the South American Biological Control Laboratory in Buenos Aires, Argentina, may have found a way to halt TSA’s dramatic spread. It seems both the larval and adult stages of a prolific beetle, Gratiana boliviana, enjoy chewing the weed to death.

The six-millimeter-long beetle, commonly known as the tortoise beetle, reproduces rapidly, attracting and seducing mates with an iridescent, turquoise-and-gold body.

Studies in Argentina and cooperative studies with University of Florida’s Julio Medal at quarantine facilities in Gainesville are helping pave the way for the beetle’s release to control TSA-infested lands. Scientists had to ensure G. boliviana would not devour important crops as well as the weed. To protect nontarget plants, extensive tests--using eggplant as a “guinea pig”--are being conducted to determine if G. boliviana could become a pest on farm crops if released to control TSA. Study results so far have eased this concern.

If, as anticipated, the beetle’s performance continues to confirm these findings, G. boliviana could be approved for release in the United States sometime in the next two years.

Read more about controlling TSA in the January issue of Agricultural Research magazine.

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