Initial screening of the stem-boring weevil Osphilia tenuipes, a candidate agent for the biological control of Bryophyllum delagoense in Australia

A stem-boring weevil, Osphilia tenuipes (Fairmaire) (Coleoptera: Curculionidae), from Madagascar, was screened in South Africa to determine its potential as a biological control agent for Bryophyllum delagoense (Ecklon & Zeyher) Schinz (Crassulaceae) in Australia. Favourable attributes of the weevil include ease of culturing, multiple generations per year, and high levels of damage inflicted on B. delagoense under laboratory conditions. Despite indications that O. tenuipes has a narrow field host range, no-choice and multiplechoice trials in quarantine revealed that it could oviposit and develop to adulthood on seven non-target species in the family Crassulaceae, without an obvious loss of fitness on four of those species. Despite these results, O. tenuipes is considered to have potential for release against B. delagoense in Australia because the continent has very few native Crassulaceae which could potentially serve as alternative hosts in the field.