Field sites and sample collections

Thirteen aquatic plant species belonging of different families and that represented a wide range of life-forms (according Cook, 1996) and taxonomic groups were target (Table 1). All plants were collected in aquatic habitats inside the Restinga de Jurubatiba National Park, Rio de Janeiro State, Brazil (SISBio 30299). Immediately after collection, the plants were conditioned in thermal boxes and transported to the laboratory. The species were identified by one of the authors (Tatiana U.P. Konno) and voucher specimens have been deposited at the Herbarium of the Rio de Janeiro Federal University, Brazil. Samples of vegetative parts of each species were separated into three groups: (1) fresh plants for use in susceptibility to consumption assays (within 48 h of collection); (2) lyophilized and ground for the assays using reconstituted plants (as artificial food) and the nutritional analyses; (3) chemical extractions to investigate the defensive capabilities.

Notes.

Specimens of the generalist herbivorous gastropod B. glabrata (Thomas, Nwanko & Sterry, 1985) (shell diameter = 1.7 ± 0.3 cm) were collected from Cabiúnas lagoon (22°16′S, 41°41′W) by actively searching through clumps of aquatic plant using a sieve. Upon collection, the gastropods were conditioned in thermal aerated boxes containing freshwater and transported to the laboratory. There, they were maintained in plastic containers (10 L) with freshwater changed daily, constant aeration, constant temperature (22 °C) and a 12:12 h light:dark photoperiod. They were fed on lettuce for 48 h until 1 h before the beginning of experiments to avoid starvation that could promote unnaturally feeding behavior during our assays (Cronin & Hay, 1996).