Tropical Soda Apple


Before and After
Gratiana boliviana
Field Release




Implementation of Biological Control
of Tropical soda Apple
Metriona elatior

The leaf-feeder beetle, Metriona elatior Klug (Coleoptera: Chrysomelidae) was screened as a biological control agent of TSA in Florida. This species does not have a common name in Brazil. Worldwide there are 19 subfamilies of Chrysomelidae (according to Seeno and Wilcox 1982) with 4 of them (Chrysomelinae, Criocerinae, Cassidinae, and Alticinae) well represented in the neotropics (Costa-Lima 1955, Blakwelder 1946).


Metriona is in the Cassidinae, a subfamily with approximately 2,000 species (Blackwelder 1946). The neotropical Cassidinae were divided by Monros and Viana (1951) into two sections: Hemisphaerotina and Cassidina. The section Cassidina was further divided into 2 sections: Omocarina and Cassidina based on taxonomic characteristics, making 3 sections (Buzzi 1994) most of them occurring in the tropics. The Cassidina section have 3 tribes: Dorynotini, Cassidini, and Charidotini (Huncks 1952). The tribe cassidini includes 10 genera: Agroiconata, Aporocassida, Gratiana, Psalidonata, Plagiometriona, Coptocycla, Syngambria, Philaspis, Drepanocassis, and Metriona (Buzzi 1988). Nine species of Metriona (Metriona argentina Spaeth, Metriona tenella Klug, Metriona bifossulata Boheman, Metriona erratica Boheman, Metriona vilis Boheman, Metriona bilimeki Spaeth, Metriona bicolor F., Metriona elatior Klug, and Metriona sexpunctata F.) have been described and/or recorded in Central/South America (Buzzi 1988, Maes and Staines 1991).

The biology of M. elatior was studied by Hill and Hulley (1996) in South Africa, by Santana, Pitelli, and Gravena, in Brazil (unpublished data), and Gandolfo in Argentina (unpublished data) under controlled laboratory conditions. Most of the information on the life-cycle of this insect that is reported here came from the laboratory studies conducted at the Universidade Estadual Paulista in Jaboticabal, São Paulo state, Brazil.

The number of egg cases laid per female varied from 31 to 109, and each egg-case contains between 1 to 21 eggs (mostly from 4 to 8 eggs). Eggs hatch in six to seven days at 25°C. Most of the egg cases are laid on the underside of the leaf, among the main veins.

Larvae undergo five instars and a non-feeding pre-pupae stage. As in many other tortoise beetles in the Cassidini tribe, the larva has spiny-form processes or scoli that extend laterally from each thoracic and abdominal segments, and two long caudal processes or anal forks that carry fecal material and exuviae. Larvae and adults feed mostly underside of the TSA leaves consuming all leaf tissues. Time taken from egg- hatching to pupation varies from 23 to 29 days.

Pupae are mostly greenish-yellow. Pupation time is from 5 to 10 days, and it occurs attached to the underside of the leaf by the last abdominal segment.

Once the adult emerge from pupae, it has a 1-2 weeks pre-oviposition period. Females live (94-139 days) longer than males (56-90 days). At least 5- generations/year can occur under optimum environmental (temperature, moisture) conditions.

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This page was last updated January, 2010