Successful Biological Control of Tropical Soda Apple (Solanales: Solanaceae) in Florida: A Review of Key Program Components

Abstract

Tropical soda apple (Solanum viarum Dunal) (Solanaceae) is a small shrub native to South America that is invasive in pastures and conservation areas across Florida. Dense patches of tropical soda apple not only reduce cattle stocking rates and limit their movement, but also serve as reservoirs for pests of solanaceous crops. A classical biological control program was initiated in 1994 with exploration for natural enemies of tropical soda apple in Argentina, Brazil, and Paraguay. Host specificity tests conducted under laboratory and field conditions demonstrated that the leaf feeding beetle Gratiana boliviana Dunal (Coleoptera: Chrysomelidae) was a specialist herbivore that completes development only on the target weed. After obtaining appropriate permits, field releases of G. boliviana were initiated in Florida in May of 2003. Larvae and adults of G. boliviana feed on tropical soda apple leaves and may completely defoliate their host plants, resulting in reduced growth and fruit production. Mass rearing facilities for the beetle were established in northern, central and southern Florida, and adults were either hand-carried or transported to release sites by overnight courier. From 2003 to 2011, a total of 250,723 beetles were released and they became established throughout Florida, however, their impact is more noticeable in regions below latitude 29 °N. Reductions of tropical soda apple densities caused by damage by the beetle were visible 2-3 yr after initial release, or in some cases, within a few months. Various methods of technology transfer were used to inform the public, land owners, funding agencies and scientists about the biological control program, including articles in trade magazines, extension publications, websites, videos, field days and scientific publications. The project was successful because of the coordinated efforts of personnel from federal, state and county agencies.