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 7th, 2014
Arcadia, FL. Summer 2005
This talk covers the successful implementation of a biological control program of tropical soda apple
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1. Background of TSA 2. Biological control agent: Gratiana boliviana
3. Mass release program of beetles 4. Establishment and impact of beetles
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 400 seeds per fruit that remain viable in soil for 2 years (Mullahey 2002)
2 cm
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.
Dense TSA infestation disrupts cattle and wildlife movement Lack of shade increases heat stress in cattle
Alachua Co.
Florida ranchers lose $6.5 to 16 million annually due to increased control costs
Hendry Co.
Increased mechanical control Reduction in stocking rates Increased chemical control
St. Lucie Co.
TSA is an alternative host for insect pests and diseases of tomato, eggplant, pepper
Early blight (Alternaria)
Mosaic Virus
Colorado Potato Beetle
Tomato hornworm
Stink bugs
Gratiana boliviana is a leaf feeding beetle found in Paraguay, Argentina and Brazil
30 days at 25oC
♀ ♂
Larvae and adults produce a ‘shot hole’ damage on the leaves
Larvae and adults feed voraciously on TSA leaves and wounds facilitate the entrance of diseases
Shot holes Skeletons
Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec.
Adults are reproductive from April to October and migrate to the ground during winter
Before the release of the beetle its host specificity was extensively studied under quarantine
Host range testing on 118 plants revealed that G. boliviana would only feed and reproduce on tropical soda apple
UF quarantine
Release Permit
SP1
SP2
SP3
SP 118
Mass rearing was conducted at several locations across Florida
DPI, Fort Pierce
USDA, Miami
UF, Gainesville
UF, Immokalee
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
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4. Establishment and impact of beetles
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
Furthest distance travelled/year = 8.1 km
Highest density was 38 beetles per plant
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Beetles negatively affected TSA performance
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plant density
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Long term monitoring study revealed a decrease in TSA densities after 2 years of beetle release
Quarterly sampling of 16, 4 m2 quadrates
Survey of ranchers to assess the effectiveness of the program
Ranchers were more aware of the beetle in Central and South Florida
34%
71%
53%
2010
48
62 55 53 51
55
North Florida Central Florida South Florida
Ranchers told us the beetle is helping at controlling TSA
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’.
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
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4. Reduction in TSA densities in C and S-FL
Questions?