Host specificity of Metriona elatior, a potential biological control agentof tropical soda apple, Solanum viarum, in the USA

The leaf beetle Metriona elatior from Brazil-Argentina was screened in the Florida (USA) State quarantine facility as a potential biological control a gent of tropical soda apple, Solanum viarum, a recently arrived weed specie s. Multiple-choice host-specificity tests were conducted in small cages (60 cm x 60 cm x 60 cm) using 95 plant species in 29 families. Adults fed heav ily on the main target weed (S. viarum), and on turkeyberry, Solanum torvum (noxious weed of Asiatic origin); fed moderately on red soda apple, Solanu m capsicoides (weed of South American origin), and eggplant, Solanum melong ena (economic crop); and fed lightly on aquatic soda apple, Solanum tampice nse (weed of Mexican-Caribbean-Central American origin), and on silverleaf nightshade, Solanum elaeagnifolium (native weed widely distributed). M. ela tior adults laid 84 to 97% of their egg masses on S. viarum, and 3 to 16% o n S. melongena. Non-choice host-specificity tests were also conducted in qu arantine in which M. elatior adults and neonate larvae were exposed to 17 a nd 19 plant species, respectively. Tests with the neonates indicate that th is insect was able to complete its development on S. viarum, S. torvum, S. melongena, and S. capsicoides. Although some adult feeding and oviposition occurred on S. melongena in quarantine on potted plants in small cages, no feeding or oviposition by M. elatior was observed in field experiments cond ucted in Brazil. Surveys in unsprayed S. melongena fields in Argentina and Brazil indicated that M. elatior is not a pest of S. melongena in South Ame rica. The evidence obtained from the South-American field surveys, Brazil o pen-field experiments, and Florida quarantine host specificity tests indica te that M. elatior causes significant feeding damage to S. viarum, and does not represent a threat to S. melongena crops in the USA. Therefore an appl ication for permission to release M. elatior against S. viarum in the USA w as submitted in October 1998.