Identification of sources of plant resistance to Diaprepes abbreviatus (Coleoptera : Curculionidae) by three bioassays

Host plant resistance to the root weevil Diaprepes abbreviatus (L.) was ass essed for 3 citrus rootstock cultivars, 5 promising hybrid rootstocks, and 3 citroid fruit trees using 3 bioassay methods: a pot bioassay with 1-yr se edlings; a new, 21-cm plastic cell bioassay with 5-mo seedlings; and a diet incorporation bioassay. The plastic cell bioassay is a more rapid screenin g method and is capable of evaluating a larger number of entries in a short er period compared with current methods. The 3 bioassays yielded similar re sults. Larval growth was inhibited by 2 of the remote citroid fruit trees, Murraya koenigii (L.) Sprengel and Glycosmis pentaphylla (Retzius) Correa, compared with growth on commercial rootstock cultivars. Specifically, larva e allowed to feed on roots of M. koenigii or G. pentaphylla gained less wei ght compared with larvae fed on the commercial rootstock cultivar 'Swingle' [Citrus paradisi Macfayden x Poncirus trifoliata (L.) Rafunesque-Schmaltz] . The resistance of G. pentaphylla confirms previous reports, M koenigii is a new source of resistance to D. abbreviatus.