Biological Control with Gratiana boliviana

Impact on TSA

Studies conducted by scientists at the University of Floridahave demonstrated that   Gratiana boliviana can reduce the density of Tropical Soda Apple after one year from the time of release. The initial density of TSA in the study site was 10 plants per 40 square feet; however, after one year, only 2 plants were found in the same area (Figure 1). Beetle populations increase in numbers during the spring and summer severely damaging the plant. As temperatures cool and day-length shortens in the fall, the beetles enter a dormant stage and populations decrease until the following spring (Figure 1).

Change in density of Tropical Soda Apple over one year

Figure 1. Change in density of Tropical Soda Apple over the one year period.

The pictures are of a hammock area in a pasture in St. Lucie Co., FL. An initial survey in July, 2006 indicated that TSA dominated the ground cover and there was a very low presence of native vegetation. Gratiana boliviana was released at this site and one year later, a drastic reduction on TSA density was noticed (see pictures below).

July 2006 TSA and October 2007