Submitted to: Diaprepes Task Force Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: January 21, 2002
Publication Date: February 9, 2002
Citation: Lapointe, S.L., Bowman, K.D. 2002. Evidence for genetic control of plant resistance in poncirus trifoliata to the diaprepes root weevil. Diaprepes Task Force Abstracts. Technical Abstract: Detecting and measuring plant resistance in citrus to the Diaprepes root weevil (DRW) are complicated by the long life cycle of both pest and host. A method was developed to screen rootstock entries as part of efforts at USHRL to develop resistant varieties. Results presented here demonstrate replicability of the method. In two trials, progeny of the trifoliate (Poncirus trifoliata) cross 'Sunki' x 'Flying Dragon' were more resistant than progeny of 'Pearl' x 'Flying Dragon'. Weight gain was consistently lower when DRW larvae were reared in pots containing progeny of 'Sunki' x 'Flying Dragon' compared with larvae reared on progeny of 'Pearl' x 'Flying Dragon'. This is the first evidence of genetic control of resistance to DRW within sexually compatible citrus rootstocks. There was a significant positive correlation between percentage root loss and larval weight gain within the resistant progeny, indicating a possible antixenotic effect. Despite efforts to control test conditions, variability in the parameter measured (weight gain) as an indicator of resistance makes it difficult to precisely characterize individual genotypes. There was a significant interaction between trial and genotype within progeny family. Despite this, the method was sufficiently robust to detect resistance at the population level. Resistance to DRW was assessed for seedlings of 56 P. trifoliata selections. Five varieties of P. trifoliata were identified as more resistant than 'Flying Dragon' based on larval weight gain.