Open Field Host Specificity Tests in Brazil for Risk Assessment of Metriona elatior (Coleoptera: Chrysomelidae), a Potential Biological Control Agent of Solanum viarum (Solanaceae) in Florida

E. Bredow, J. H. Pedrosa-Macedo, J. C. Medal, J. P. Cuda

Abstract


Open field experiments were conducted in Brazil to assess the suitability of the South American leaf feeding beetle Metriona elatior Klug for biological control of tropical soda apple, Solanum viarum Dunal in the USA. A multiple choice open field test with eggplant (Solanum melongena L.), bell-pepper (Capsicum annuum L.), potato (Solanum tuberosum L.), tomato (Lycopersicon esculentum Mill.), giló (Solanum gilo Raddi), falsa-jurubeba (Solanum fastigiatum Willd.), and the target weed Solanum viarum, was conducted at the Universidade Federal do Paraná Experimental Station in Curitiba. A second multiple choice-test was conducted 2 years later at the same location excluding the target weed and exposing M. elatior adults to S. melongena, S. tuberosum, L. scullentum, and C. annuum. An S. viarum control plot was established 60 km from the choice-test field. In total, 276 teneral adult beetles were released in the first multiple choice-test. In the second test, 176 beetles were released in the choice-test plot that excluded S. viarum, and 172 adult beetles were released in the S. viarum control plot at different developmental stages of the tested plants. All the plants in each plot were visually checked once a week and the number of adults, immatures, and eggs recorded. Results in the first multiple choice-test showed a complete rejection of the crop plants by M. elatior. Minor feeding (<3%) was observed on eggplant in the second experiment in which S. viarum was excluded from the crop plots, but all M. elatior larvae died in less than a week. The tests were ended when the plants started to senesce. The results of these open field tests corroborate previous quarantine/laboratory host specificity tests indicating that host range expansion of M. elatior to include the solanaceous crops tested is highly unlikely. A petition to release M. elatior in the USA was submitted to the TAG committee in September 2006.

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