Differential performance of tropical soda apple and its biological control agent Gratiana boliviana (Coleoptera: Chrysomelidae) in open and shaded habitats.
The leaf feeding beetle Gratiana boliviana Spaeth has been released since 2003 in the southeastern United States for biological control of tropical soda apple, Solanum viarum Dunal. In Florida, G. boliviana can be found on tropical soda apple growing in open pastures as well as in shady  wooded areas. The objectives of this study were to determine the effect of light intensity on the performance of tropical soda apple and G. boliviana under greenhouse conditions, and to determine the abundance and mortality of G. boliviana in open and shaded habitats. Leaves growing in the  shade were less tough, had higher water and nitrogen content, lower soluble sugars, and less dense and smaller glandular trichomes compared with leaves growing in the open. Plants grew slightly taller and wider under shaded conditions but total biomass was significantly reduced compared with  plants grown in the open. In the greenhouse, G. boliviana had higher immature survival, greater folivory, larger adult size, and higher fecundity when reared on shaded plants compared with open plants. Sampling of field populations revealed that the overall abundance of G. boliviana was lower  but leaf feeding damage was higher in shaded habitats compared with the open habitats. The percentage of eggs surviving to adult was greater in shaded compared with open habitats. The abundance of predators was higher in the open pasture and was positively correlated with the abundance of  G. boliviana. These results indicate that not only plant quality but also habitat structure are important to the performance of weed biological control agents.
Biological Control Research and Containment Laboratory, University of Florida, 2199 South Rock Rd., Ft. Pierce, FL 34945, USA. rrdg@ufl.edu
Rodrigo
R
Diaz
Carlos
C
Aguirre
Gregory S
GS
Wheeler
Stephen L
SL
Lapointe
Erin
E
Rosskopf
William A
WA
Overholt
D000818:Animals; D061046:Biological Control Agents; D001517:Coleoptera / Q000254:growth & development / Q000502:physiology*; D004777:Environment; D005247:Feeding Behavior; D005260:Female; D005431:Florida; D020387:Food Chain; D007814:Larva / Q000254:growth & development / Q000502:physiology; D008027:Light; D008297:Male; D010572:Pest Control, Biological / Q000379:methods*; D011156:Population Density; D011157:Population Dynamics; D032322:Solanum / Q000254:growth & development* / Q000502:physiology
D061046:Biological Control Agents