PHYTOPHAGOUS INSECTS ASSOCIATED WITH PISTIA-STRATIOTES IN FLORIDA

During July 1985 to June 1986, we surveyed the arthropod fauna associa ted with Pistia stratiotes L., waterlettuce, in Florida. Plant samples were collected at 61 sites. Samples comprised a minimum of 20 waterle ttuce rosettes. Invertebrates were removed from the plant sample using a submergence technique. Eighteen phytophagous species were recovered from P. stratiotes. Six of these species are known waterlettuce feede rs. They include the moths Petrophila drumalis (Dyar), Synclita oblite ralis (Walker), and Samea multiplicalis Guenee, the aphid Rhopalosiphu m nymphaeae L., the leafhopper Draeculacephala inscripta Van Duzee, an d the weevil Tanysphyrus lemnae (F.). Most of these insects are either stenophagous or polyphagous; none feed exclusively on waterlettuce. T he paucity of specialists on waterlettuce in Florida contrasts sharply with the richness of oligophagous species in South America. This sugg ests that waterlettuce is not a native species, despite observations o f its occurrence in Florida as early as the mid-1700s.