Biological Control of Tropical Soda Apple in Florida Rodrigo Diaz William A. Overholt Stephen Hight Amy Roda Julio Medal Ken Hibbard Aquatic Weed Control Short Course May 7 th, 2014 Arcadia, FL. Summer 2005
Beetles/plant This talk covers the successful implementation of a biological control program of tropical soda apple 1. Background of TSA 2. Biological control agent: Gratiana boliviana 3. Mass release program of beetles 4. Establishment and impact of beetles Plants / 4 m 2 15 10 5 0 Jul 06 Oct 07 Jan 09 30 20 10 0-10
Tropical soda apple (Solanum viarum) is a species of the nightshade family, Solanaceae Shrub, perennial, up to 1.5m tall Leaves and stems covered with prickles Racemes of white flowers Leaves are sticky due to trichomes
Tropical soda apple is a prolific seed producer TSA can flower and fruit all year 2 cm 400 seeds per fruit that remain viable in soil for 2 years (Mullahey 2002)
Movement of TSA is facilitated by mammals, and the transport of contaminated hay and turf Collier Co.
TSA has been reported in several states; however, it is a major problem only in Florida also in Texas Mexico Source: EDDMaps Source: EDDMaps October 2010 First report in Florida: 1988
TSA is invasive in open pastures as well as in shaded hammocks DeSoto Co. Alachua Co. Dense TSA infestation disrupts cattle and wildlife movement Lack of shade increases heat stress in cattle
Florida ranchers lose $6.5 to 16 million annually due to increased control costs Hendry Co. St. Lucie Co. Increased mechanical control Reduction in stocking rates Increased chemical control
TSA is an alternative host for insect pests and diseases of tomato, eggplant, pepper Colorado Potato Beetle Early blight (Alternaria) Stink bugs Tomato hornworm Mosaic Virus
2. Biological control agent: Gratiana boliviana
Gratiana boliviana is a leaf feeding beetle found in Paraguay, Argentina and Brazil 30 days at 25 o C
Larvae and adults produce a shot hole damage on the leaves Shot holes Skeletons Larvae and adults feed voraciously on TSA leaves and wounds facilitate the entrance of diseases
Adults are reproductive from April to October and migrate to the ground during winter Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec.
Before the release of the beetle its host specificity was extensively studied under quarantine UF quarantine Release Permit SP 1 SP 2 SP 3 SP 118 Host range testing on 118 plants revealed that G. boliviana would only feed and reproduce on tropical soda apple
3. Mass release program of beetles
Mass rearing was conducted at several locations across Florida UF, Gainesville DPI, Fort Pierce UF, Immokalee USDA, Miami This project was successful in part due to close collaboration of agencies
Releases targeted initially to counties with large TSA infestations Okeechobee, Osceola, Highlands, Glades, St. Lucie Source: National Agricultural Statistics Service, USDA
Releases were conducted by ranchers, extension agents and researchers
Beetles/plant 4. Establishment and impact of beetles Plants / 4 m 2 14 12 10 8 6 4 2 0 Jul 06 Oct 07 Jan 09 30 25 20 15 10 5 0-5
After five year of releases, a survey was conducted to monitor the establishment and impact of beetles 38 counties with a total 113 of random sites Plant and beetle variables collected
Beetle densities were higher in St. Lucie and Okeechobee Furthest beetles were found from a release site was 32.4 km Average distance travelled / year = 4.7 km Highest density was 38 beetles per plant Furthest distance travelled/year = 8.1 km
cm or number Beetles negatively affected TSA performance 120 100 80 60 A B A B GB No GB 40 20 0 Height Diameter Fruit A B
Beetles/plant Long term monitoring study revealed a decrease in TSA densities after 2 years of beetle release 14 30 Plants / 4 m 2 12 10 8 6 4 plant density beetles/plant 25 20 15 10 5 2 0 0 Jul 06 Oct 06 Jan 07 Apr 07 Jul 07 Oct 07 Jan 08 Apr 08 Jul 08 Oct 08 Jan 09 Apr 09 Jul 09-5 Quarterly sampling of 16, 4 m 2 quadrates
Before and after the beetle: St. Lucie Co. July 2006 October 2007
Before and after the beetle: St. Lucie Co. July 2006 October 2007
Before and after the beetle: Polk Co. May 2003 June 2007
Before and after the beetle: Okeechobee Co. June 2005 July 2005 August 2007
Survey of ranchers to assess the effectiveness of the program 34% 71% 53% Ranchers were more aware of the beetle in Central and South Florida 2010
Ranchers told us the beetle is helping at controlling TSA North Florida Central Florida South Florida 48 62 55 53 51 55 How common are the beetle in the ranch? How is the level of success of these beetles? 54% of cattle owners in C and S-FL stated that the beetles were responsible for TSA control in their properties
Pamphlets, how-to manuals and videos used to communicate to a wider audience Videos include the rancher perspective, how to recognize beetles and plants and how biological control works.
Beetles/plant Each step in the biological control program of TSA was crucial for the overall success 1. Recognition of impact of TSA 2. Availability of host specific agent 3. Effective release program 4. Reduction in TSA densities in C and S-FL Plants / 4 m 2 15 30 10 20 10 5 0 0-10 Jul 06 Oct 07 Jan 09 Questions?