Host specificity of Anthonomus tenebrosus (Coleoptera: Curculionidae), a potential biological control agent of tropical soda apple (Solanaceae) in Florida

Abstract

Multiple-choice and no-choice tests were conducted at the Florida Department of Agriculture quarantine facility to determine the host specificity of the South American flower bud weevil, Anthonomus tenebrosus Boheman, intended for biological control of the exotic weed tropical soda apple (TSA), Solanum viarum Dunal in Florida, USA. Ninety-one plant species in 21 families were included in multiple-choice feeding and oviposition experiments, including the target weed and the 6 major cultivated Solanaceae: bell pepper (Capsicum annuum L.), chili pepper (C. frutescens L.), tomato (Lycopersicon esculentum Mill.), tobacco (Nicotiana tabacum L.), eggplant (Solanum melongena L.), and potato (Solanum tuberosum L.). Plant bouquets with flower-buds of 8 to 10 randomly selected plant species, always including TSA (S. viarum) were exposed to 10-20 A. tenebrosus adults for 1 to 2 weeks. Oviposition and feeding were observed twice a week. No-choice host-specificity tests were also conducted with A. tenebrosus adults using potted flowering plants. Ten adults were exposed to 29 plant species individually tested for 1 to 2 weeks. Plant species in each test were replicated 3 or 4 times. All tests showed that A. tenebrosus fed and laid eggs only on the target weed. No eggs were deposited on any of the other of the 91 plant species tested. Host-specificity tests indicated that a host range expansion of A. tenebrosus to include any of the crops, and native Solanaceae, and non-solanaceous plants tested is highly unlikely. A petition for field release in the USA was submitted to the Technical Advisory Group for Biological Control Agents of Weeds (TAG) in Oct 2007.