Graminea

We tested the leaf-feeder beetle, Gratiana graminea Klug (Coleoptera: Chrysomelidae) as a biological control agent of TSA in Florida. It was first collected by the late Daniel Gandolfo (Argentina USDA-ARS Laboratory) and Julio Medal on TSA in Rio Grande do Sul, Brazil in April 2000. The identity of G. graminea was confirmed by Dr. Z. J. Buzzi, Universidade Federal do Paraná in Curitiba, Brazil. This species does not have a common name in Brazil. According to Seeno and Wilcox (1982) there are 19 subfamilies of Chrysomelidae worldwide with 4 of them (Chrysomelinae, Criocerinae, Cassidinae, and Alticinae) well represented in the neotropics (Costa-Lima 1955, Blakwelder 1946).
TAXONOMY AND GENERAL BIOLOGY
The genus Gratiana is in the Cassidinae, a subfamily with approximately 2,000 species (Blackwelder 1946). The neotropical Cassidinae was divided by Monrós 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, with most of them occurring in the tropics (Buzzi 1994). The Cassidina section has 3 tribes: Dorynotini, Cassidini, and Charidotini (Huncks 1952). The tribe cassidini includes 10 genera: Agroiconata, Aporocassida, Coptocycla, Drepanocassis, Gratiana, Metriona, Philaspis, Plagiometriona, Psalidonata, and Syngambria (Buzzi 1988). Eight species of Gratiana (Gratiana boliviana Spaeth, Gratiana conformis Boheman, Gratiana graminea Klug, Gratiana insculpta Boheman, Gratiana inurbana Weise, Gratiana lutescens Boheman, Gratiana pallidula Boheman, Gratiana spadicea (Klug) have been described and/or recorded in the New World. Most of them (6) are found in the neotropics (Maes and Staines 1991, Buzzi 1994, 1995) and only 2 species (G. lutescens & G. pallidula) are reported in North America (Siebert 1975). The distribution of G. graminea in Brazil can be observed in Figure 2. The known host plants of G. graminea in Brazil are: Solanum viarum & Solanum aculeatissimum. The biology of this beetle was studied by J. Medal at the quarantine facility in Gainesville, Florida, and by M. Vitorino under controlled laboratory conditions in Brazil (unpublished data).
Eggs are laid individually on TSA leaves and petioles, and not in clusters as those of G. lutescens, G. palidulla (Siebert 1975), and G. spadicea (Becker and Freiro-Costa 1988). Eggs are initially whitish and become light green colored during the incubation period. They are cylindrical, 1.18 ą .006 in length and 0.52 ą 0.04 in width. Each egg is laid with the long axis parallel to the leaf surface, and enclosed by two brownish translucent membranes. The membrane against the leaf surface is attached to the ventral and lateral areas of the egg following its shape. The other membrane is attached to the egg dorsally and forms two wings with a serrate margin on each side of the egg. The egg case is attached to the leaf surface by one end. The mean incubation period was 6.04 ą 0.70 days at 24ş C.
Larvae undergo five instars. Newly hatched larvae are cream colored. Time taken from egg-hatching to pupation varied from 14 to 20 days. Larva undergoes four 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.
Pupation time is from 6 to 9 days, and it occurs attached to the leaf by the last abdominal segment.
Once the adult emerge from pupae, it has 8-12 days pre-oviposition period. Copulation has been observed a few hours after adult eclosion and throughout the oviposition period. The number of eggs per female ranged from 112 to 325 (n=10) with an oviposition peak between the third and sixth week when females laid approximately 5 eggs per female per day. At least 4-generations/year can occur under optimum environmental (temperature, moisture) conditions.